The complete FUN TO IMAGINE with Richard Feynman
摘要
TLDRIn this detailed lecture, the speaker explores the varying ease with which people understand science, attributing differences partly to interests and cognitive approaches. The complexities of scientific concepts often require deep imagination, particularly when visualizing the atomic and quantum world. Richard Feynman embarks on a discussion about atomic motion, explaining phenomena like heat as atomic jiggling and describing atoms as small units with distinct behaviors unlike everyday objects. He delves into the nature of magnetic and electrical forces, explaining how these forces are part of the fundamental interactions within atoms. The lecture also touches on cosmic phenomena, such as neutron stars, black holes, and quasars, illustrating the extreme outcomes of gravitational forces and stellar evolution, helping highlight the imaginative challenges faced when conceptualizing the universe at atomic and cosmic scales. The lecture encourages a playful engagement with scientific concepts, viewing them through imaginative scenarios, and highlights the relationship between astronomy, electromagnetism, and quantum mechanics, creating a fascinating portrait of the natural world's mysteries awaiting discovery.
心得
- 🧠 Imagination is key to understanding science.
- 🌡️ Heat comes from atomic jiggling.
- 🧲 Magnets work due to electron alignment.
- 🌌 Neutron stars and black holes demonstrate extreme gravity.
- 🔬 Small-scale behaviors differ from large-scale ones.
- 📡 Electric and magnetic forces are interconnected.
- 📖 Understanding comes from studying and exploring.
- 💡 Science allows us to visualize unseen phenomena.
- 🌠 Astronomical observations expand our cosmic understanding.
- 🔍 Telescopes reveal distant stars and galaxies.
时间轴
- 00:00:00 - 00:05:00
Some individuals find science intriguing and simple, whereas others find it challenging and uninteresting. This disparity is particularly noticeable in children, with varied levels of enthusiasm across different subjects, similar to music. The difficulty often lies in the imaginative aspect needed to conceptualize scientific ideas, such as imagining how temperature relates to the atomic jiggling of particles. Understanding science requires recognizing these conceptual frameworks where heat is the result of atomic motion, akin to atoms jiggling rigorously in hot substances.
- 00:05:00 - 00:10:00
The concept of energy loss and perpetual motion in atoms, as explained through bouncing balls, illustrates how energy is transferred between atoms, leading to heat generation. Atoms never lose energy when they bounce; instead, they move perpetually. The heat transfer process, akin to pounding an object, increases its temperature. Atoms in any material are in constant motion, and understanding this can make comprehending scientific phenomena more accessible and enjoyable. This perpetual atomic motion echoes even in the surface tension seen in water drops, showcasing physics' universality.
- 00:10:00 - 00:15:00
Imagination enhances the understanding of scientific phenomena, such as cooling water's effect on trapping atoms in a structured pattern forming solids. This scientific basis for matter states is also demonstrated in gases, where high energy and rapid atomic movement prevent bonding. Personal experiments with bicycle pumps and observing gas compression provide insights into atomic behaviors underpinning heat transfer and gas laws. Embracing imagination in science turns abstract concepts, like energy transfer, into relatable phenomena, making the subject engaging and relevant.
- 00:15:00 - 00:20:00
One's curiosity about science can drive a persistent fascination with understanding bodily reactions, such as the tightening of atoms in rubber bands due to heat. This understanding, explained through atomic interactions and elasticity principles, reveals the endless dance of atoms beneath ordinary experiences. Embracing this perspective unveils the hidden beauty in everyday occurrences. People must overcome seeing these concepts as mundane; instead, imagination should guide them towards inquiry and discovery.
- 00:20:00 - 00:25:00
Scientific curiosity pushes individuals to question phenomena like magnetism and motion, fostering knowledge-building. Discourses about phenomena naturally lead to inquiries about underlying principles and explanations. Addressing curiosity by understanding frameworks where certain principles are accepted aids in navigating scientific inquiry's complexities. Through inquiry, knowledge is gathered, which broadens the understanding of our universe's intricate, interconnected mechanisms.
- 00:25:00 - 00:30:00
Deep scientific exploration involves understanding foundational principles like magnetic forces, rooted in electrical attraction and repulsion. Questions about these forces' nature often unfold into deeper inquiries, prompting scientists to accept some phenomena as fundamental. Explaining forces in the universe, such as electricity and magnetism, involves recognizing their integral roles. Analogies can sometimes help, but acknowledging limits in understanding the deepest forces is critical for appreciation and further discovery.
- 00:30:00 - 00:35:00
Scientific exploration often reveals the interconnectedness of forces that operate across great distances, challenging human intuition shaped by everyday experiences. Electrical forces, for example, demonstrate profound effects unseen in familiar scales. This allows for technological applications such as telecommunications. The exploration of these elemental forces expands human capability, proving that embracing scientific curiosity can lead to groundbreaking discoveries and technological advancements, rooted in fundamental forces.
- 00:35:00 - 00:40:00
Observing astronomical scales requires redefining perspectives due to vast celestial distances and numerous stars. Telescopes enhance human vision, but comprehending astronomical phenomena like galaxies necessitates appreciating universal scale proportions. While stars seem innumerable, celestial events often challenge imagination, requiring dynamic understanding. Astronomical studies demand embracing the enormity of the universe while maintaining a sense of humility about humanity’s place within it.
- 00:40:00 - 00:45:00
Astronomy requires creative hypothesis generation and imagination due to unknown phenomena like the mysterious nature of neutron stars and pulsars. Imagination assists in formulating models within scientific constraints, as exhibited by Oppenheimer's neutron stars' development. These pulsars spin rapidly, indicating great density, challenging traditional understandings of stellar behavior. Explaining celestial phenomena often demands phenomenally imaginative thinking while adhering to known laws.
- 00:45:00 - 00:50:00
Science continually evolves through imaginative thinking, requiring creative efforts to interpret astronomical phenomena like quasars and black holes. Gravity dynamics highlight black holes as gravitational enigmas absorbing light, with potential explanations for bright emissions from quasars. Imagination is vital for conceptualizing such dense stellar structures, demonstrating the necessity of creative descriptions for understanding these gravitational mysteries. Yet, science remains challenged by vast, unknown cosmic interactions.
- 00:50:00 - 00:55:00
Laypersons can cultivate similar imaginative capabilities in science with dedication and study. Pursuing scientific knowledge involves regularly engaging in analysis, understanding equations, and exploring nature's laws. Scientists build expertise similarly to developing other skills—through practice, problem-solving, and continuous learning. A strong foundation in scientific principles can drive innovation and a deep understanding of the natural world, highlighting the accessibility of science to all curious minds.
- 00:55:00 - 01:00:00
Imaginative thinking in science, while complex, involves moments of chaos partially solved through fragmentary associations during scientific inquiry. Scientists often communicate complex ideas differently due to individual cognitive processes. Understanding time perception and parallel cognitive tasks shows personal cognitive diversity, amplifying insights into how individuals process scientific complexities. While challenging, the imaginative approach is crucial in scientific inquiry, demonstrating varied understanding frameworks.
- 01:00:00 - 01:06:49
Engaging with quantum mechanics underscores how human intuition is challenged by the peculiar behavior of subatomic particles compared to larger scales. Descriptions of atomic behavior defy simple, familiar imagery, highlighting the limitations in picturing quantum realms without mathematics. While practical examples illustrate atomic principles, translating these into intuitive, everyday images remains problematic. Future generations may develop new methods of internalizing quantum behaviors, overcoming current intuitive challenges.
思维导图
常见问题
Why do some people find science easy and others hard?
It may be due to individual differences in interests or cognitive styles. Some people naturally gravitate towards imaginative and abstract thinking, which can make science more comprehensible and enjoyable.
What makes science difficult?
Science can be difficult because it requires a lot of imagination to understand concepts that might not be directly observable or intuitive.
How is heat explained in atomic terms?
Heat is described as the jiggling of atoms. When atoms jiggle more, they create more heat, and when they jiggle less, they create less heat.
What is a neutron star?
A neutron star is a dense astronomical object, the remnants of a massive star, where atoms are so closely packed that protons and electrons combine into neutrons.
What are black holes and quasars?
Black holes are regions with gravity so strong that nothing, not even light, can escape. Quasars are extremely luminous objects believed to be powered by black holes at the center of galaxies.
How do magnets work?
Magnets work due to magnetic forces, which arise from the alignment of spinning electrons within atoms, leading to attraction or repulsion between objects.
How do telescopes work?
Telescopes collect light from a large area and concentrate it into a small area to study distant celestial objects, allowing for the observation of weaker light sources.
What happens in a nuclear star?
In a neutron star, nuclear matter is compacted tightly together, leading to a star that is very dense and has strong gravitational pull.
Why is iron magnetic?
Iron is magnetic because its atoms can align their spinning electrons in the same direction, enhancing magnetic forces and causing attraction.
How is electricity related to magnetism?
Electricity and magnetism are closely related through electromagnetic forces, where moving electric charges create magnetic fields and vice versa.
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- 00:00:11It's interesting that some people find science so easy
- 00:00:14and others find it kind of dull and difficult
- 00:00:18especially kids you know, some of them are just eat it up
- 00:00:22and I don't know why it is, it's the same perhaps for all subjects
- 00:00:25For instance lot of people love music and I could never carry a tune
- 00:00:28and I lose a great deal a pleasure out of that
- 00:00:33and I think that people lose a lot of pleasure who find the science dull
- 00:00:37In the case of science, I think that one of the things that make it very difficult
- 00:00:43is that it takes a lot of imagination
- 00:00:44It's very hard to imagine all the crazy things that things really are like
- 00:00:54Nothing's really as it seems, we used to get you know hot and cold
- 00:00:58and all that hot and cold is the speeds that the atoms are jiggling
- 00:01:03if they jiggle more it corresponds to hotter and colder is jiggling less
- 00:01:07So if you have a bunch of atom, like a cup of coffee or something, sitting on a table
- 00:01:15and the atoms are jiggling a great deal and they bounce against the cup
- 00:01:20and the cup then gets shaking and the atoms in the cup shake
- 00:01:23and the bounce against each other and the heat heats the cup and heats everything else
- 00:01:26and then hot things spread that heat to other by mere contact
- 00:01:32because the atoms that are jiggling a lot in the hot thing
- 00:01:35shake the ones that are jiggling only a little bit in the cold thing
- 00:01:39so that the hot (heat we say) goes into the cold thing, it spreads
- 00:01:45but what is spreading is just jiggling, an irregular motion, but it is easy to kind of understand.
- 00:01:53It brings up another thing that's kind of curious:
- 00:01:58that I say that things jiggle and if you're used to balls bouncing
- 00:02:04you know they slow up and stop after a while
- 00:02:08but we have to imagine with the atoms a perfect elasticity they never lose any energy
- 00:02:13every time they bounce they keep on bouncing all the time they don't lose anything
- 00:02:16they're perpetually moving
- 00:02:18And that the things that happen when we say something loses energy
- 00:02:21if a ball comes down and bounces,
- 00:02:24it shakes irregularly some of the atoms in the floor
- 00:02:27and when it comes up again, it leaves some of the atoms moving, they jiggling
- 00:02:32So as it bounces, it is passing its extra energies, its extra motions
- 00:02:38to little patches on the floor each time it rebounces and it loses a little heat each time
- 00:02:43until it settles down, we say as the falling motion stops
- 00:02:47But what's left is the floor is shaking more than it was before
- 00:02:50and the atoms in the ball are shaking more than they were before
- 00:02:53that the organized motion of all these atoms moving the same way falling down
- 00:02:58and the quiet floor, is now transformed into a ball sitting on the ground
- 00:03:03But all the motion is still there in the form of energy of motion
- 00:03:07in the form of the jiggling of the floor which is a little bit warmer (unbelievable!).
- 00:03:12But anybody who's hammered a great deal on something knows that it's true
- 00:03:16that if you pound something and hit it a lot
- 00:03:19you can feel the temperature difference it heats up
- 00:03:21it heats up simply because you're jiggling it
- 00:03:25this picture of atoms is a beautiful one
- 00:03:27that you can keep looking at all kinds of things this way
- 00:03:29you see a little drop of water a tiny drop
- 00:03:34and the atoms attract each other they like to be next to each other
- 00:03:38they want as many partners as they can get
- 00:03:40Now the guys at the surface have only partners on one side
- 00:03:44here in the air on the other side so they're trying to get in
- 00:03:47And you can imagine this team of people, this team in people, all moving very fast
- 00:03:52all try (to get) to have as many partners as possible
- 00:03:55and the guys on the edge are very unhappy and nervous and they keep pounding in
- 00:03:59trying to get in, and that makes a tight ball instead of a flat
- 00:04:03and that's what you know surface tension
- 00:04:05when you realize when you see how sometimes a water drop sits like this on a table
- 00:04:10then you start to imagine why it's like that
- 00:04:13because everybody is trying to get in to the water
- 00:04:15and at the same time while all this is happening, other atoms leaving the surface
- 00:04:20and the water drop is slowly disappearing
- 00:04:23I find myself trying to imagine all kinds of things all the time
- 00:04:26and I get a kick out of it like a runner gets a kick out of sweating
- 00:04:30I GET A KICK of thinking about these things!
- 00:04:36I can't stop I mean if you may I could talk forever
- 00:04:40If you could cool off the water
- 00:04:42so that the jiggling is less and less, it jiggles slower and slower
- 00:04:45then the atoms get stuck in a place, they like to be with their friend
- 00:04:49there's force of attraction and they get packed together,
- 00:04:53they're not rolling over each other, they're in a nice pattern
- 00:04:56like oranges in a crate in a nice organized pattern, all just jiggling in place
- 00:05:01but not having enough motion to get loose of their own place
- 00:05:05and to break the structure down
- 00:05:07And that what I'm describing is a solid, it's ice, it has a structure
- 00:05:11If you held the atom in one end in a certain position
- 00:05:13all the rest are lining up in a position sticking out
- 00:05:17and it’s solid at the end
- 00:05:19whereas if you heat that harder
- 00:05:21then they begin to get loose and roll all over each other
- 00:05:24and that's the liquid.
- 00:05:25And if you heat that still harder, then they bounce still harder
- 00:05:28and they simply bounce apart from each other
- 00:05:30and they're just individuals,
- 00:05:32I said atoms, these are really little groups of atoms: molecule
- 00:05:35which come flying and hit
- 00:05:37and although they have a tendency to stick, they're moving too fast
- 00:05:41their hands don't grab so to speak, as they pass
- 00:05:44and they fly apart again and this is the gas we call steam
- 00:05:50You can get all kinds of understanding
- 00:05:52When I was a kid with this "air", I was always interested in
- 00:05:56I've noticed that when I pumped up my tires on the bicycle
- 00:05:59you can learn a lot by having a bicycle
- 00:06:01I'd pump up the tires that the pump would get hot
- 00:06:04and that also understand we see as the pump handle comes down
- 00:06:08and the atoms are coming up against it and bouncing off and it's moving in
- 00:06:11the ones that are coming off have a bigger speed than the ones that are coming in
- 00:06:15so that as it comes down and each time they collide
- 00:06:18it speeds them up
- 00:06:20and so they're hotter when you compress the gas it heats
- 00:06:22and when you pull the piston back out
- 00:06:25then the atoms which are coming faster than the piston feel receiving
- 00:06:28or sort of a give it gives and it comes out with less energy
- 00:06:32it's like going up against something which is soft and yielding it go boom boom
- 00:06:36and it loses so as you pull the piston out
- 00:06:38and the atoms are hit they lose their speed and they cool off
- 00:06:42and gases are cool when they expand
- 00:06:45and the fun of it is that all these things which you see or you notice in the world
- 00:06:50about it the pump heats the gas and the gas cools when it expands
- 00:06:54or the steam evaporates until you cover the cover
- 00:06:57and all these things you can understand from these simple pictures
- 00:07:01and that's kind of a lot of fun to think about
- 00:07:04I don't want to take this stuff seriously
- 00:07:06I think we should just have fun imagining it not worry about
- 00:07:10there's no teacher going to ask you questions at the end
- 00:07:13otherwise it's a horrible subject
- 00:07:21the atoms like each other the different degrees
- 00:07:26oxygen for instance in the air would like to be next to carbon
- 00:07:29and if they're getting near each other they snap together
- 00:07:34if they're not too close though they repel and they go apart
- 00:07:37so they don't know that they could snap together
- 00:07:39it's just as if you had a ball that was trying to climb a hill
- 00:07:41and there was a hole it could go into like a volcano hole
- 00:07:45a deep one it's rolling along it doesn't go down in the deep hole
- 00:07:49because if it starts to climb the hill and then rolls away again
- 00:07:52but if you made it go fast enough it'll fall into the hole
- 00:07:56and so if it's have something like wood in oxygen
- 00:08:00there's carbon in the wood from a tree
- 00:08:03and the oxygen comes and hits it carbon but not hot enough
- 00:08:08it just goes away again the air is always coming nothing's happening
- 00:08:12if you can get it faster by heating it up somehow somewhere
- 00:08:16somehow get it started a few of them come fast they go over the top so to speak
- 00:08:20they come close enough to the carbon and snap in
- 00:08:22and that gives a lot of jiggly motion which might hit some other atoms
- 00:08:26making those go faster so they can climb up and bump against other carbon atoms
- 00:08:31and they jiggle and they make other jiggle, and you get an horrible catastrophe
- 00:08:35which is one after the other all these things are going faster and faster
- 00:08:38and snapping in and the whole thing is changing
- 00:08:41that catastrophe is a fire
- 00:08:45it's just a way of looking at it
- 00:08:46and these things are happening they perpetual
- 00:08:48once it gets started it keeps on going
- 00:08:50the heat makes the other atoms capable of reaching to
- 00:08:54make more heat to make other atoms and so on
- 00:08:56so this terrible snapping is producing a lot of jiggling
- 00:09:00and if I put with all lack activity of the atoms there
- 00:09:03and I put a cup of coffee over that mess of wood that's doing this
- 00:09:08it's going to get a lot of jiggling so that's what the heat of the fire is
- 00:09:13and then of course uh
- 00:09:14you see what's happening when you start thinking, just go on and on
- 00:09:18wonder how did it get started
- 00:09:21why is it that the wood's been sitting around all this time with the oxygen all this time and it didn't do this earlier or something
- 00:09:27where did I get this from?
- 00:09:31well it came from a tree
- 00:09:34and the substance of a tree is carbon, where did that come from?
- 00:09:38that comes from the air it's carbon dioxide from the air
- 00:09:41people look at trees and they think it comes out of the ground
- 00:09:44the plants grow out of the ground
- 00:09:46but if you ask where the substance comes from
- 00:09:49you find out where do they come from
- 00:09:51the trees come out of the air?
- 00:09:53they surely come out of you know they come out of the air
- 00:09:56the carbon dioxide in the air goes into the tree
- 00:09:59and it changes it kicking out the oxygen
- 00:10:03and uh pushing the oxygen away from the carbon
- 00:10:06and leaving the carbon substance with water water comes out of the ground you see
- 00:10:11only it had to get in there it came out of the air didn't it
- 00:10:14it came down from the sky
- 00:10:15so in fact most of a tree almost all of the tree is out of the ground
- 00:10:20I'm sorry it's out of the air
- 00:10:22there's a little bit from the ground some minerals and so forth
- 00:10:26now of course I told you the oxygen and we…
- 00:10:31oxygen carbon stick together very tight
- 00:10:34how is that the tree is so smart to take the carbon dioxide
- 00:10:38which is carbon and oxygen nicely combined
- 00:10:40and undo that so easy?
- 00:10:42Ah! Life! Life has some mysterious force!
- 00:10:45No! The sun is shining, and this sunlight comes down
- 00:10:49and knocks this oxygen away from the carbon,
- 00:10:52so it takes sunlight to get the plant to work!
- 00:10:55and so the sun, all the time, is doing the work of separating the oxygen away from the carbon
- 00:10:59the oxygen is some kind of terrible by-product, which it spits back into the air
- 00:11:04and leaving the carbon and water and stuff to make the substance of the tree
- 00:11:09and then we take the substance of the tree to get the fireplace
- 00:11:14and there's all the oxygen made by these trees
- 00:11:17and all the carbons would much prefer to be close together again
- 00:11:21and once you let the heat to get it started
- 00:11:24it continues and make an awful lot of activity while it's going back together again
- 00:11:30and all those nice light and everything comes out
- 00:11:32and everything is being undone you're going from carbon and oxygen back to carbon dioxide
- 00:11:38and the light and heat that's coming out, that's the light and heat of the sun that went in
- 00:11:43so it's sort of stored sun that is coming out when you burned a log
- 00:11:52next question: how is the sun so jiggly, so hot?
- 00:11:57I gotta stop somewhere; I leave you something to imagine
- 00:12:12most elastic things like steel springs and so on is nothing but this electrical thing pulling back
- 00:12:18you pull the atoms up a little bit apart when you bend something
- 00:12:21and then they try to come back together again
- 00:12:24but rubber bands work on a different principle
- 00:12:28there there's some long molecules like chains
- 00:12:33and other little ones that are shaking all the time that are bombarding them these chains
- 00:12:38and the chains are all kind of kinky and knockabout in shape
- 00:12:42when you pull open the rubber band the strings get straighter
- 00:12:46but these strings are being bombarded on the side
- 00:12:49by these other atoms trying to shorten them by kinking them
- 00:12:52so it pulls back it's trying to pull back
- 00:12:55and it's pulling back only because of the heat
- 00:12:59so if you heat a rubber band it'll pull strong more strongly
- 00:13:02for instance if you hang a weight with a rubber band put a little match to it
- 00:13:06it's kind of fun to watch it rise because heats want
- 00:13:08and there's another thing you can check that this idea is right
- 00:13:12that is heat that drives a rubber band
- 00:13:15if you pull the band out just like when we push the piston and the gas
- 00:13:20if you pull the band out
- 00:13:21this tightening string hitting those molecules makes them move faster so it's warmer
- 00:13:27and if you take the band and let it in
- 00:13:31then the molecules hitting the strings which sort of give as the thing hits it
- 00:13:35they give in to the soft like and they lose energy when they hit these retiring band, string
- 00:13:44so it cools
- 00:13:46and there is a little way you can do this
- 00:13:47you're not very sensitive it's a small effect
- 00:13:49and if you take a fairly wide rubber band and put it between your lips
- 00:13:53and pull it out you'll certainly notice it's hotter
- 00:13:57and if you then hold it out and let it in you'll notice it's cooler
- 00:14:00at least you'll notice a certain difference in whether
- 00:14:03what happens when you expand it and when you contract it
- 00:14:05and that's i've always found rubber bands fascinating to think
- 00:14:09that when they're sitting on an old package of papers for a long time
- 00:14:14holding those papers together
- 00:14:16it's done by a perpetual pounding pounding pounding
- 00:14:19and the atoms that get these chains to hold it, try to kink them and try kink them
- 00:14:23year after year well rubber bands don't last that long
- 00:14:26but anyhow for a long time trying to hold this whole thing together
- 00:14:31The world is a dynamic mess of jiggling things if you look at it right
- 00:14:36And if you magnify, you will hardly see a little thing anymore
- 00:14:39because everything is jiggling in its own pattern, and there's a lot of little balls
- 00:14:43It's lucky that we have such a large scale of view of everything that we can see these as "things"
- 00:14:48without having worry about all these little atoms all the time
- 00:14:57If you get hold of two magnet and you push them
- 00:15:00you can feel this pushing between them.
- 00:15:02Turn around the other way and they slam together
- 00:15:05Now, what is it, the feeling between those two magnets?
- 00:15:09what do you mean "what's the feeling between two magnets when you hold them"?
- 00:15:11well, there's something there, isn't it?
- 00:15:12I mean that the sensation that they're something there when you push the two magnets together.
- 00:15:17Listen to my question
- 00:15:18what is the meaning when you say that there's there's a feeling
- 00:15:21of course you feel it. Now what do you want to know?
- 00:15:24What I want to know is what's going on, between these two bits of matter?
- 00:15:29magnets repel each other
- 00:15:30Well then, what does that mean or why are they doing that or how are they doing that?
- 00:15:40I'm not saying... That's a perfectly reasonable question.
- 00:15:42Of course it's a reasonab... it's an excellent question. Okay?
- 00:15:49But the problem that you are asking, you see,
- 00:15:51when you ask why something happens
- 00:15:56how does a person answers "why something happens?"
- 00:16:00for example
- 00:16:03Aunt Minnie is at the hospital. Why? Because she slip.
- 00:16:07she went out and she slipped on the ice and broke her hip
- 00:16:10that satisfies people. It satisfies
- 00:16:14but wouldn't satisfy someone who came from another planet knew nothing about things
- 00:16:17first you understand "Why when you break your hip you go to the hospital?
- 00:16:22"How do you get to the hospital when the hip is broken"
- 00:16:25well because her husband seeing that she had her hip broken
- 00:16:28called the hospital up and send somebody to get her
- 00:16:30all that is understood by people
- 00:16:33now when you explain a "Why"
- 00:16:36you have to be in some framework that you allow something to be true
- 00:16:41Otherwise you are perpetually asking why
- 00:16:43Why did the husband call up the hospital?
- 00:16:45Because the husband is interested in his wife's welfare. Not always
- 00:16:50some husbands aren't interested in their wives' welfare when they are drunk and angry
- 00:16:54So you begin to get very interesting understanding of the world and all its complications
- 00:16:59in order to… if you try to follow anything up
- 00:17:02you go deeper and deeper in various directions.
- 00:17:05for example you could go “why did she slip upon the ice?"
- 00:17:08Well ice is lippery everybody knows that no problem
- 00:17:12But you ask "why is ice slippery?"
- 00:17:15that's kind of curious, ice is extremely slippery it's very interesting
- 00:17:19You say "How does it work?"
- 00:17:21you could either say "I'm satisfied that you have answered me ice is slippery, that explains it"
- 00:17:27or you could go on and say "Why is ice slippery?”
- 00:17:31and then you're involved with something
- 00:17:32because there are not many things as slippery as ice
- 00:17:35It's very hard to get greasy stuff, but that's a sort of wet slimy
- 00:17:40But a solid that is so slippery? Because it is in the case of ice
- 00:17:46when you stand on it (they say), momentarily the pressure melts the ice a little bit
- 00:17:51so you get a sort of instantaneous water surface on which you are slipping
- 00:17:56Why on ice and not on other things?
- 00:17:57Because ice expands… water expands when it freezes
- 00:18:01so the pressure tries to undo the expansion and melts it.
- 00:18:04It is capable about melting it
- 00:18:05But other substances contract when they're freezing
- 00:18:08and when you push them they're just satisfied to be solid
- 00:18:13why does water expand when it freezes
- 00:18:15and another substance don't expand when they freeze
- 00:18:17all right? I'm not answering the question
- 00:18:19but I am telling you how difficult a "why" question is.
- 00:18:22You have to know what it is that you are permitted to understand
- 00:18:27and allow to be understood and known
- 00:18:29and what it is you're not
- 00:18:31you'll notice in this example that the more I ask why, it gets interesting after all
- 00:18:36that's my idea that the deeper thing is the more interesting in it
- 00:18:40and you can even go further and say "Why did she fall down when she slip?"
- 00:18:46That has to do with gravity
- 00:18:47and involves all other planets, and everything else
- 00:18:49never mind, it goes on and on!
- 00:18:52Now when you ask for example "Why two magnets repel?"
- 00:18:56there are many different levels
- 00:18:58it depends on whether you are a student of physics
- 00:19:00or an ordinary person who doesn’t know anything or not
- 00:19:02If you are somebody that doesn't know anything about
- 00:19:04all I can say is that it is the magnetic force that makes things repel
- 00:19:08And that you are feeling that force. You see, that is very strange
- 00:19:13because I don't feel kind of force like that in other circumstances.
- 00:19:16When you turn them in the other way they attract
- 00:19:18there's a very analogous force, electrical force
- 00:19:21which is the same kind of a question and you say that's also very weird
- 00:19:25but you're not at all disturbed by the fact
- 00:19:26that when you put your hand on the chair, it pushes you back.
- 00:19:30But we have find that looking at it that it is the same force as a matter of fact
- 00:19:34the electrical force (not magnetic exactly in that case)
- 00:19:37but it is the same electric repulsions that are involved in keeping you finger away from the chair
- 00:19:42because everything is made out... it is electrical force in minor, microscopic details
- 00:19:48there are other forces involved, but they are connected to electrical force
- 00:19:52It turns out that the magnetic and the electric forces with which I wish to explain these things
- 00:19:56this repulsion in the first place
- 00:19:59is what ultimately is the deeper thing that we have to start
- 00:20:02that we can start with to explain many other things that looks like they were...
- 00:20:07Everybody would just accept them.
- 00:20:09You know you cannot put your hand through the chair, that's taken for granted.
- 00:20:14But you can't put your hand through the chair when you look at it more closely: "Why?"
- 00:20:18it involves these same repulsive forces that appear in magnets
- 00:20:23The situation is then to have to explain is:
- 00:20:25"why in the magnet it goes over a bigger distance than ordinarily?"
- 00:20:28There it has to do with the fact that in iron, all the electrons are spinning in the same direction,
- 00:20:34they all get lined up and they magnify the effect of the force
- 00:20:38until it's large enough at a distance that you can feel it
- 00:20:41but it's a force which is present all the time and very common
- 00:20:45and is in a basic force or almost
- 00:20:48I mean I can go a a little further back if I went more technical
- 00:20:51but in the early level, I just have to tell you
- 00:20:54that is going to be one of the thing you will have to take as an element in the world
- 00:20:58the existence of magnetic repulsion or electrical or magnetic attraction
- 00:21:04I can't explain that attraction in terms of anything else that is familiar to you.
- 00:21:10For example, if we say that the magnets attracts like if they were connected by rubber bands
- 00:21:15I would be cheating you
- 00:21:17because they are not connected by rubber bands; I shouldn't be in trouble
- 00:21:20you'll soon ask me about the nature of the bands
- 00:21:23And secondly, if you are curious enough you will ask me
- 00:21:26"why rubber bands tend to pull back together again?"
- 00:21:29I would end up explaining that in terms of electrical forces
- 00:21:33which are the very things I try to use the rubber band to explain
- 00:21:36so I have cheated very badly you see
- 00:21:40So I'm not going to be able to give you an answer to "why magnets attract each other"
- 00:21:44except to tell you that they do
- 00:21:47and to tell you that's one of the elements in the world among different forces:
- 00:21:51there are electrical forces, magnetic forces,
- 00:21:53gravitational forces and others, and those are some of the parts
- 00:21:58If you are a student, I could go further and tell you
- 00:22:01that the magnetic forces are related to the electrical forces very intimately
- 00:22:06that the relationship between the gravity forces and the electrical forces remains unknown
- 00:22:11and so on.
- 00:22:13But I really can't do a good job, any job of explaining magnetic forces in terms of something else that you are more familiar with,
- 00:22:21because I don't understand it in terms of anything else that you are more familiar with.
- 00:22:31The stuff of fantasizing in looking at the world, imagining things, which really isn't fantasizing
- 00:22:37because you just try to imagine the way it really is, comes up handy sometimes
- 00:22:43The other day I was at the dentist, he was getting ready with this electric drill to make holes
- 00:22:49and I thought I'd better think of something fast or else it's gonna hurt.
- 00:22:54And then I thought about this little motor going around
- 00:22:57and what was that make it turn? And what was going on?
- 00:23:02and what's going on is that there's a dam some distance away here
- 00:23:07and water going over the dam turns a great big wheel, alright
- 00:23:12and this wheel is connected with long thin pieces of copper
- 00:23:19which split up into other pieces of copper and split up and spread all over the city
- 00:23:24and then they're connected back to another little gadget and makes wheels turn
- 00:23:29all the wheels in the city are turning, because this thing turns.
- 00:23:33If this thing stops, all the wheels stop. If it starts again, they all start again.
- 00:23:38And I think it's kind of a marvelous thing of nature. It's extremely curious that phenomenon
- 00:23:46I like to think about a lot, because all it is, it's copper and iron.
- 00:23:51see, sometimes we think it's man-made generator very complicated,
- 00:23:54the phenomenon is a result of somet special something that we've made.
- 00:23:59But it's nature doing it, and it's just iron and copper; if you just take a big long loop of copper,
- 00:24:06and add iron at each end and move the piece of iron here, the other iron move at the other piece.
- 00:24:11And if you get it down to the NOTHING
- 00:24:14here just moving piece of iron in a loop a copper and see other piece of iron move
- 00:24:19you realize what a fantastic mystery nature is!
- 00:24:27you don't even need the iron
- 00:24:30you could if you at least get this pump prime primed and started by
- 00:24:35jiggling copper strands around fast enough knotting them and unknotting them and so forth
- 00:24:40you can get other copper strands move at the other end, over a long connection.
- 00:24:45And what is it? It's only copper! And motion!
- 00:24:51We're so used to circumstances in which these electrical phenomena are all canceled out
- 00:24:59Everything is sort of neutral: pushing and pulling, it's all very dull.
- 00:25:03But nature has these wonderful things
- 00:25:05Magnetic forces and electrical forces when you comb your hair
- 00:25:08with your comb and you get some strange condition
- 00:25:11so you put it in front of a piece a paper, that lifts up the paper, the paper jiggles at a distance far away
- 00:25:18that in fact turns out that that is the thing that's deeper inside of everything than the things we're used to
- 00:25:30We're used to forces that only act directly, right?
- 00:25:33you push with your finger, it only acts directly,
- 00:25:37but then you have to imagine what it is that's pushing with the finger
- 00:25:40here's this finger is made of little balls of atoms.
- 00:25:44And it has got another bunch of atoms that are pushing it.
- 00:25:47At that little space between those atoms. And that pushing is going through that space.
- 00:25:52And the only thing that happens with the comb and the paper is that the circumstances have a reason
- 00:25:59which makes it possible to see those forces go through a bigger distance than just the short distance between the atoms
- 00:26:08What it is they have charges like electrons, that are both the same
- 00:26:13they repel each other with a force. They are very tiny parts, they are piece of the atoms
- 00:26:17and they repel each other with a force which is enormous
- 00:26:21it's inversely as the square of the distance just like gravity is inverse to the square of the distance
- 00:26:26but gravity is attractive whereas this one is repulsive
- 00:26:29and for two electrons the gravity is so weak compared to the electricity
- 00:26:34electricity is so much more enormous than the gravity
- 00:26:37I can't express because I don’t know the name of the numbers
- 00:26:39it's one with thirty eight or forty zeros after the one
- 00:26:44Bigger is electricity!
- 00:26:45It's so enormous, that if I were all electrons... well, the number is too big!
- 00:26:54There's also however for electrical thing other kind of charges, positive charges
- 00:26:59example of protons are positive, they're inside the nucleus of the atoms and the attract electrons
- 00:27:04Opposite charges attracts, alike charges repel
- 00:27:07So you have to imagine enormous forces
- 00:27:11where likes are trying to get away from likes, and unlikes are trying to get near the opposite
- 00:27:17What would happen if you had a lot of them?
- 00:27:19they'd be all the likes would collect with unlike, they attract each other
- 00:27:24and they'd get an intimate mixture of pluses and minuses all on top of each other, very close together
- 00:27:29You wouldn't have a lot of pluses anywhere, because they repel each other
- 00:27:32They're all being compensated with minus very close,
- 00:27:35and you get these little knots of plus and minus
- 00:27:38the reason that the knots don't get smaller and smaller is because they are particles and there are quantum mechanical effects
- 00:27:43that we won’t discuss that don’t make they can't get any smaller than a certain size
- 00:27:47So you get these little lumps which are balls, they are the atoms
- 00:27:52The atoms are positive and negative charges and they neutralize
- 00:27:55they cancel their charges as nearly as they can
- 00:27:58and because of these force are so big, it ends up nowhere, with very little left
- 00:28:04because they're so big they cancels out, there's always so exactly the same pluses and minuses in any normal material
- 00:28:11When you comb your hair, it rubs just a little bit extra off
- 00:28:15just a few extra minuses say here, and somewhere else a few extra pluses
- 00:28:19But the forces are so big that just the extra ones
- 00:28:23which make a force that we can see, that seems to get over a long range
- 00:28:28and that we find mysterious and that we need an explanation for
- 00:28:33and we try to find an explanation for it in terms of ideas
- 00:28:36like forces that are inside of rubber bands, or steel bars and twisted things
- 00:28:42We would like to have some kind of puller, at a distance
- 00:28:45because we're used to it that we don't get any push until we're touching
- 00:28:49but the fact is that the reason we don't get any push until we're touching
- 00:28:52is the same force as you see at a long distance only it's come down to short
- 00:28:57because the pluses and minuses have cancelled out so well that you don't feel anything until it gets very very close
- 00:29:03When it gets close enough of course it makes a difference
- 00:29:05which is plus and which is minus and where they are and they repel each other
- 00:29:08so it's kind of fun to imagine that this intimate mixture of highly attractive opposites
- 00:29:16which are so strong that they cancel out the effects
- 00:29:18and it's only sometimes, when you have an excess of one kind or another that you get this mysterious electrical force
- 00:29:28And how can I explain the mysterious electrical forces in any other way?
- 00:29:31Why should I try to explain it in terms of something like jelly or other things which are made?
- 00:29:39And I understand the other way around in terms of strong, long distance forces which are all canceled out
- 00:29:45So it's the electrical forces in fact, and the magnetic forces in fact that we have to accept as the base reality
- 00:29:54in which we are going to explain all the other things.
- 00:29:58So again it turns out it's hard to understand, you have to do a lot of imagining
- 00:30:02that the real world has as its base, a force that acts at long distance
- 00:30:10that we haven't got much experience with that force
- 00:30:14we have peculiar phenomena here and there, but ordinarily
- 00:30:18we don't have much experience with that force is simply because that's what requires explanation
- 00:30:23That's what requires imagination. The long distance force we haven't other picture for
- 00:30:30And in the example of the generator for instance
- 00:30:38what happens is that the electrons which are part of an atom
- 00:30:43they're pushed by the motion of the copper wires
- 00:30:50wonderful to think that if you push a few here, and they get too close together
- 00:30:54so they push the others because they repel at a long distance
- 00:30:56so it's not just like water which repel at a short distance
- 00:30:59but it's a wonderful fluid which repel at a long distance
- 00:31:03and the effects therefore can go very quickly through the wire
- 00:31:05there is a little concentration you go ZINNNG through the wire all over the city at once.
- 00:31:09And you can use that stuff to make signals,
- 00:31:13you can push a few electrons here and there by talking in a telephone,
- 00:31:16at the other end of the line, a long line of copper across the city the electrons respond
- 00:31:22because of this very rapid interactions over these long distances to what you're saying in this room
- 00:31:28and they discovered experimentally
- 00:31:32the existence of these long forces and that this rapid motion action and so forth
- 00:31:38was a tremendous thing for human beings
- 00:31:40I think that the discovery of electricity and magnetism and the electromagnetic effects
- 00:31:45which are finally worked out, the full equations were worked out by Maxwell in 1873
- 00:31:52probably the most fundamental transformation, the most remarkable thing in history
- 00:32:00the biggest change in history
- 00:32:10I went to a scientific school-MIT, and then fraternity when you first join
- 00:32:16they try to keep you from being feeling that you're too smart
- 00:32:22by giving you what looked like simple questions to try to figure out what actually happens
- 00:32:27and it's like training for imagination you know, it's kind of fun
- 00:32:31and I'd tell you some of them that I remember
- 00:32:34I learned them of course once you learn them
- 00:32:36the next time somebody comes along with this wonderful puzzle
- 00:32:40you look at them kind of quietly you wait two or three seconds or five seconds
- 00:32:43to show ways that you were thinking
- 00:32:45and then you come up with this answer to astonish your friends
- 00:32:49but the fact was of course that you were trained by your fraternity brothers
- 00:32:52as to how to answer these things early on
- 00:32:55one of the questions we used to we got was the problem about the mirror
- 00:32:59it's an old-fashioned it's an old problem
- 00:33:02You look in a mirror, and let's say you part your hair in the right side
- 00:33:07and you look in the mirror and the image has got its hair part on the left side
- 00:33:10so the image is left to right mixed up it's not top and bottom mixed up
- 00:33:15because the top of the head of the image is on the top and the bottom of the feet are at the bottom
- 00:33:20and the question is how does the mirror know to get the left and right mixed up and not the up and down
- 00:33:25you get a better idea of the problem if you think of lying down and looking at the mirror
- 00:33:30all right your hair is still on the left side
- 00:33:32and now the left and right was the up and down
- 00:33:35Whereas the up and down which look okay was the left and right before
- 00:33:38and the mirror somehow figured out what you are gonna do when you're looking at it
- 00:33:42so what to describe in a sort of symmetrical way what the mirror does
- 00:33:47that it doesn't look lopsided and it takes left and mixes it up with right
- 00:33:50and doesn't do the same with up and down
- 00:33:54and after a lot of fiddling you gradually read we can worked out the answer to that one
- 00:33:59you see if you wave this hand
- 00:34:02then the hand in the mirror that waves is the right opposite at it
- 00:34:05The hand on the east is the hand on the east and the hand on the west is the hand on the west,
- 00:34:10and the hand that head that up is up and the feet that is down is down.
- 00:34:14Everything is really all right!
- 00:34:16but what's wrong is if this is north
- 00:34:19your nose is to the north of the back of your head,
- 00:34:22but in the image the nose is to the south of the back of the head
- 00:34:26so what happens really in the image is neither the left and the right mixed nor the top and the bottom,
- 00:34:31but the front and back had been reversed, you see
- 00:34:33that is just the nose of the thing is on the wrong side of the head if you want it, all alright?
- 00:34:38Now ordinarily when we think of the image we think at it as of another person
- 00:34:42and we think the normal way that another person would get on that condition over there
- 00:34:45It's a psychological thing
- 00:34:47We don't think of the idea that the person has been squashed and pushed backward with his nose and his head
- 00:34:52because that's not what ordinarily happens to people
- 00:34:54A person gets to look like you looks in the mirror by walking around and facing you
- 00:35:00and because people when they walk around don't turn their head for their feet
- 00:35:04we leave that part alone
- 00:35:05but they get their right and left hand swung about you see when they turn around
- 00:35:09so we say that it's left and right interchanged
- 00:35:13but really the symmetrical way is along the axis of the mirror that thing get interchangeable
- 00:35:17but that's kind of an easy one
- 00:35:19a harder one and very entertaining was
- 00:35:22"what keeps a train on the track?"
- 00:35:25And of course the answer is, as everyone thinks: the flanges on the wheels
- 00:35:30you know the wheels have some kind of flange on them
- 00:35:32but that's not the answer. Because flange is just safety devices
- 00:35:36if the flanges rub against the tracks you hear a terrible squealing
- 00:35:40they're just in case the real mechanism doesn't work
- 00:35:44there's another problem with trains that's connected to it
- 00:35:47now people all know this about their automobile that when you go around the corner
- 00:35:53the outside wheels have to go further than the inside wheels
- 00:35:56and if the wheels were connected on a solid shaft
- 00:35:59you couldn't do that you can't turn the outside wheels further than the inside wheels
- 00:36:04and so the shaft is broken in the middle with a gear system it's called a differential
- 00:36:09did you ever see the differential on a railroad train?
- 00:36:12no you look at those wheels under a freight car
- 00:36:15and there are the two wheels
- 00:36:16and there's a solid steel rod going from one wheel to the other
- 00:36:20there's nothing that one turns the same as the other
- 00:36:22so now how does it go around the corner, a curve?
- 00:36:25when the outside wheel has to go further than the inside wheel
- 00:36:29and the answer is that the wheels are flanged like this
- 00:36:33I mean not flange they're cones this way
- 00:36:38that is they're a little fatter closer to the train and a little thinner further out
- 00:36:42if you look closely you'll see they've got this beveled edge
- 00:36:45and it's all very simple
- 00:36:46when they go around the curve, they slide out on the track a bit
- 00:36:51So that this wheel travels on a fatter pond a bigger diameter
- 00:36:56and this on a smaller diameter
- 00:36:57so when they both turn one turn this swings further than the other
- 00:37:03and that's what keeps it on the track also the same way
- 00:37:05suppose the train's running along on this thing, on the track
- 00:37:09and the track's here and here the two wheels are exactly balanced and it's nice and even
- 00:37:13suppose accidentally it gets a bump or something and slides out this way
- 00:37:17then this wheel is on a bigger circumference than this one
- 00:37:20but they're on a solid shaft
- 00:37:22so when it turns once around
- 00:37:24it carries this wheel forward relative to the other
- 00:37:27and steers the train back on the track
- 00:37:29of course if it gets too far off on the other side it goes back and forth and it stays on the track
- 00:37:33because the wheels are tapered and the flange is safety
- 00:37:37well we had a lot of stuff like that that we had to learn you know
- 00:37:40that would get straightened out before we could become full-fledged members of the fraternity
- 00:37:54If I'm sitting next to a swimming pool and somebody dives in
- 00:37:59and she's not too pretty, so I can think of something else
- 00:38:02I think of the waves and things that have formed in the water
- 00:38:06and when there's lot's of people that have dived in the pool, there's a very great choppiness of all these waves all over the water,
- 00:38:13and to think that it's possible, maybe, that in those waves there a clue as to what's happening in the pool,
- 00:38:18that some sort of insect or something with sufficient cleverness,
- 00:38:22could sit in the corner of the pool and just be disturbed by the waves,
- 00:38:26and by the nature of the irregularities and bumping of the waves have figured out
- 00:38:31who jumped in, where and when and what's happening all over the pool.
- 00:38:36And that's what we're doing when we're looking at something:
- 00:38:39the light that comes out is waves
- 00:38:42just like in the swimming pool, except in 3 dimensions
- 00:38:44instead of 2 dimensions of the pool and it's going in all directions
- 00:38:48and we have a 8'th of an inch black hole into which these things go,
- 00:38:53which is particularly sensitive to parts of the wave that are coming in a particular direction
- 00:38:58and it's not particularly sensitive when they're coming in at the wrong angle,
- 00:39:01which we say is from the corner of our eye,
- 00:39:03and if we want to get more information from the corner of our eye, we swivel this ball about so that the hole moves from place to place.
- 00:39:10Then,
- 00:39:13it's quite wonderful that we figure out so easy;
- 00:39:18that's really because the light waves are easier and the waves in water are a little bit more complicated;
- 00:39:23it would have been harder for the bug than for us, but it's the same idea,
- 00:39:26to figure out what the thing is that we're looking at at a distance,
- 00:39:32and it's really kind-of incredible because when I'm looking at you,
- 00:39:35someone standing to my left can see somebody who's standing at my right;
- 00:39:39that is, the light could be going right across this way, the waves are going this way,
- 00:39:43the waves are going this way, the waves are going this way, it's just a complete network.
- 00:39:48Now, it's easy to just think of them as arrows passing each other, but that's not the way it is,
- 00:39:52because all of this is something shaking -it's called the electric field,
- 00:39:55but we don't have to bother with what it is- it's just like the water height is going up and down.
- 00:39:59So there's some quantity shaking about here
- 00:40:02and the combination of motions that's so elaborate and complicated that the result is to produce an influence which makes me see you.
- 00:40:08At the same time, completely undisturbed by the fact that there are influences that represent the other guy seeing him on this side.
- 00:40:16So that there's this TREMENDOUS mess of waves all over in space which we call
- 00:40:24which is the light bouncing around the room and going from one thing to the other,
- 00:40:28because of course most of the room doesn't have 8'th inch black holes. It's not interested in that light,
- 00:40:34but the light is there anyway, and it bounces off this, and it bounces off that,
- 00:40:38and all this is going on, and yet we can sort it out with this instrument.
- 00:40:45But beside all that, you see, those waves that I was talking about in the water,
- 00:40:49maybe they're so big - some of them - and then there's slower swashes which are longer, and shorter.
- 00:40:54Perhaps that animal is making it's study only using waves between this length and that length,
- 00:40:59so it turns out that the eye is only using waves between this length and that length,
- 00:41:05except those two lengths are 100,000'th of an inch - 100,000'th of an inch big,
- 00:41:13and what about the slower swashes?
- 00:41:15The waves that go more slowly, that have a longer distance from crest to trough.
- 00:41:20Those represent heat. We feel those, but our eye doesn't see them focused very well, we don't in fact at all.
- 00:41:27The shorter waves are blue, the longer waves are red. But when it gets longer than that then we call them infrared.
- 00:41:35And all this is in there at the same time. That's the heat.
- 00:41:39Pit viper that get down here in the desert, they have a very little thing that they can see longer waves
- 00:41:46and pick up mice, which are radiating their heat in the longer waves
- 00:41:51but their body heat by looking at them with this eye, which is the pit of the pit viper.
- 00:41:57But we can't, we are not able to do that.
- 00:41:59And then these waves get longer and longer, and all through the same space,
- 00:42:03all these things are going on at the same time, so that in this space, there's not only my vision of you,
- 00:42:10but information from Moscow Radio that's being broadcasted at present moment, and the seeing of somebody from Peru.
- 00:42:18All the radio waves are just the same kind of waves, only they are longer waves.
- 00:42:22And there's the radar, from the airplane which is looking at the ground to figure out where it is, which is coming to the room at the same time.
- 00:42:29Plus X-rays, cosmic rays and all of these other things that are the same kind of waves,
- 00:42:33EXACTLY the same kind of waves, but shorter, faster or longer, slower.
- 00:42:37It is exactly the same thing.
- 00:42:39So this big field, this - this area of irregular motions of this electric field, this vibration, contains this tremendous information,
- 00:42:50and it's ALL REALLY there, that's what gets you.
- 00:42:54If you don't believe it, then you pick a piece of wire and connect it to a box
- 00:43:01and in the wire the electrons would be pushed back and forth by this electric field, swashing just at the right speed for the certain kind of long waves,
- 00:43:08and you turn some knobs on the box to get the swashing just right, and you hear Radio Moscow!
- 00:43:13Then you know that it was there. How else did it get there?
- 00:43:15It was there all the time. It is only when you turn on the radio that you notice it.
- 00:43:20But that all these things are going through the room at the same time which everybody knows,
- 00:43:25but you gotta stop and think about it to really get the pleasure
- 00:43:29about the complexity - the INCONCEIVABLE nature of nature.
- 00:43:43When we were talking about the atoms, one of the trouble we have with the atoms is
- 00:43:46that they are so tiny and it is so hard to imagine the scale.
- 00:43:50The atoms are in size compared to an apple is the same scale as an apple is compared to the size of the earth.
- 00:43:58That's kind of a hard think to take, and you have to go through all these things all the time
- 00:44:02and people find these numbers inconceivable and I do too
- 00:44:06And the only thing you do is just change your scale
- 00:44:08you just think of small balls but you don't try to know exactly how small they are too often
- 00:44:13or you get kind of a bit nutty, alright?
- 00:44:16but in astronomy you have the same thing in reverse
- 00:44:20because the distances to these stars are so enormous
- 00:44:23You know that light goes so fast, and it only takes few seconds to go to the moon and back
- 00:44:28or it goes around the earth in seven and a half times in a second
- 00:44:32and it goes for years... two years, three years before it gets to the nearest other star that there is to us!
- 00:44:38But all our stars are in nearby galaxies, a big mess of stars which is called a galaxy, a group
- 00:44:47but our galaxy is (what is it) some hundred thousand light years, like 100 000 years
- 00:44:54And then there's another patch of stars
- 00:44:56It takes a million years for the light to get here going at this enormous rate
- 00:45:01and you just go crazy trying to make too real that distance.
- 00:45:05You have to do everything in proportion. That's easy
- 00:45:07say that galaxies are little patches of stars and they're ten times as far apart as they are big
- 00:45:12So that's an easy picture. But you just go to a different scale, that's easier
- 00:45:16once in a while you try to come back to earth scale to discuss the galaxies, but it's kind of hard
- 00:45:23The number of stars we see at night is only about five thousand.
- 00:45:28but the number of stars in our galaxy, the telescope have shown when you improve the instruments
- 00:45:33Oh! We look at a galaxy, we look at the stars, all the light that we see, the little tiny influence,
- 00:45:40spread from the stars over this enormous distance of what three light-years for the nearest stars
- 00:45:44on! on! on! this light from the star is spreading, the wavefront's getting wider and wider
- 00:45:49weaker and weaker, weaker and weaker out into all of space
- 00:45:52and finally the tiny fraction that comes in one square eighth of an inch little black hole
- 00:45:57and does something to me so I know it's there!
- 00:46:01Well to know a little bit more about, I'd rather gather a little more of this tiny fraction of the front of light
- 00:46:08and so I make a big telescope which is a kind of funnel.
- 00:46:12The light that comes over this big area-200 inches in cross-is very carefully organized
- 00:46:17so it is all concentrated back so it can go through pupil.
- 00:46:20Actually it's better to photograph, and nowadays they use photocells which are better instruments
- 00:46:25but anyway the idea of a telescope is to focus the light from a bigger area into a smaller area
- 00:46:30so that we see things that are weaker, less light
- 00:46:32and in that way we find there's a very large number of stars in the galaxy.
- 00:46:37There's so many that if you try to name them, one in a second, all of the stars in our galaxy
- 00:46:43I don't mean all the stars in the universe just this galaxy here
- 00:46:47it takes three thousand years! And yet that's not a very big number
- 00:46:51Because if those stars were to drop one dollar bill on the earth
- 00:46:56during a year each star dropping one dollar bill
- 00:46:59they might take care of the deficit, which is suggested for the budget of the United States!
- 00:47:06So you see what kind of numbers we have to deal with!
- 00:47:09Anyway I think that the numbers are problems in astronomy, the size and numbers
- 00:47:14the best thing to do is to relax and enjoy the tininess of us and the enormity of the rest of the universe
- 00:47:22Of course, if you're feeling depressed by that, you can always look at it the other way
- 00:47:26and think how big you are compared to the atoms and the parts of atoms then you're an enormous universe to those atoms
- 00:47:33so you can sort of stand in the middle and enjoy everything both ways
- 00:47:38But the great part of astronomy is the imagination that is necessary to guess what kind of structures
- 00:47:46what kind of things can be happening to produce the light and the effect of the light of the stars that we do see
- 00:47:53and I could take an example, a historical example
- 00:47:58many times in science, by using imagination you imagine something
- 00:48:02which could be according to all the known knowledge and the laws
- 00:48:06and you don't know whether it is yet or not
- 00:48:09And that's very interesting, there is a creative imagination you'd like to call it
- 00:48:13not just imagining thing that are relatively easy, but something different
- 00:48:16And to take an example of, a star as we understand it
- 00:48:20ordinary stars like the Sun, which is just a big ball of gas, of hydrogen
- 00:48:24that's burning up the hydrogen and so forth and it's an enormous mass of gas
- 00:48:28and it's held together by gravity
- 00:48:31you don't to always understand gravity as a curved space
- 00:48:34good enough for the purpose that a force inversely square the distance
- 00:48:37When the things are closer together, the force is stronger, and it pulls everything together
- 00:48:42By the way that's why the world is round:
- 00:48:45because the globe of earth is pulled together as much as possible
- 00:48:48and if it had a great mountain and an irregularity like a bump
- 00:48:51so it would be pulled in by gravity and it all gets smooth
- 00:48:54Rocks aren't strong enough to hold a bump much bigger than a few miles
- 00:48:58and Mount Everest is our biggest bump
- 00:49:00But on the moon where the gravity is less, the bumps are higher; the mountains are bigger on the moon.
- 00:49:05Anyway, to get back to the star, it's all held together by gravity
- 00:49:09and it's got a nuclear fuel which we've haven't been talking about
- 00:49:14that's burning up the hydrogen and generating energy which keeps things going
- 00:49:17And after a while, it would use the fuel a lot
- 00:49:19people began to think about what would happen then
- 00:49:22and it would be possible to just be gas sort of hanging around held together by gravity but quiet
- 00:49:28but another possibility was to think
- 00:49:31if I push the stuff together closer, the gravity is stronger, would hold it together.
- 00:49:37Well if you push a little bit together, the pressure increases
- 00:49:41when you push the gas together, there are more atoms and they pound on it
- 00:49:44so the pressure is higher but the gravity is stronger
- 00:49:47and it turns out the pressure wins so it would just come out again
- 00:49:50if you're pushing a star like that, it oscillates
- 00:49:53and there are some stars that are oscillating and vibrating and so on
- 00:49:56but it turns out if you keep on analyzing
- 00:49:59you push it together very far to the incredible concentration
- 00:50:03that the whole mass of the sun is down to the size of the earth or smaller
- 00:50:08then it turns all the nuclear matter all the nuclei of the atoms are all stuck next to each other tight
- 00:50:15Spaces where the electrons are all squashed out and it comes out
- 00:50:19when you get to THAT far, the gravity is strong enough to overpower the pressure again
- 00:50:25even though the pressure has got to be enormous, the gravity has to be even more enormous
- 00:50:30and the thing will stay steady at a different size
- 00:50:32and be nothing but a neutron, a nuclear matter, nothing solid, nuclear matter
- 00:50:39and this possibility was worked out by Oppenheimer and Volkov, it's called a neutron star
- 00:50:46And people waited to see if there were any such neutron stars for years
- 00:50:50until recently they found these strange pulsars which emit flashes of radio waves later they found light
- 00:51:00which can go 30 times a second for instance the fastest ones or maybe 10 times a second or one a second
- 00:51:07And at first, that's very mysterious; you are used to stars being big and slow
- 00:51:12how can anything in a star move in a thirtieth of a second?
- 00:51:15Well these things are very small neutron stars and they’re spinning very fast.
- 00:51:21For reason not yet understood, they are emitting a beam, a beam of radio waves
- 00:51:25like a search light in an airport or something those things that go around boop boop boop
- 00:51:29so we get the flashes tick tick tick, that fast
- 00:51:33to imagine a star the mass of the sun, doing something, turning so fast 30 times a second
- 00:51:39another one of these big numbers, hard to conceive imaginary things okay?
- 00:51:45and the whole idea that there could be a star of such enormous density that a teaspoon would weigh so much
- 00:51:51of the matter if you put it on the earth surface it is so heavy that that it will just plough right to the center of the earth!
- 00:51:57and things like that, it took a lot of imagination:
- 00:52:01it comes out the mathematics and the analysis of all this helps you to make sure you are not making a mistake
- 00:52:06and it turns out that such a star is possible, and it turned out a little bit later they do exist
- 00:52:11and that's a good example of how imagination is a useful thing
- 00:52:17and produces a guessing ahead of time and how we make advances by using it
- 00:52:23Besides, the very difficult thing of imagining all the things that might be up there to explain the things we see
- 00:52:30in the case of astronomy, we have a large number of things we see
- 00:52:34that we have not yet quite clearly got the imagination to see what it is that's producing them
- 00:52:41Quasars are very powerful sources of light and radio waves from very great distances
- 00:52:47and we see them because they are so bright.
- 00:52:50The exact cause of their sources is gradually been recently understood
- 00:52:56in terms of another nutty concept of imagination: the black hole
- 00:53:01which is something that comes from following the logic of gravity of Einstein to its ultimate
- 00:53:09working out the consequences in crazy circumstances
- 00:53:12Suppose you had an amount of matter so great
- 00:53:16that the gravity force is so much that even light trying to get out falls back
- 00:53:23Nothing can go faster that light, and nothing could escape. You couldn't see it!
- 00:53:28how would you get there? If you have a large amount of matter to start with, it could fall together
- 00:53:34and get into this condition that no longer could the light come out.
- 00:53:37So you would have this thing which continues to attract things to it
- 00:53:41things would go in and nothing would come out. That is called the black hole.
- 00:53:46and you say well how can a black hole which is absorbing everything make all this energy that we see
- 00:53:51Is that an explanation of a quasar? Actually, it may well be
- 00:53:54Because the things that are falling in don't go pluck in but go around, falling in by swirling
- 00:54:01then as they are falling irregularly and so forth, and in the fast motions that it produces they go down this whirlpool
- 00:54:08they generate a lot of energy and friction and so forth, and different kind of effects
- 00:54:12magnetic and electric effects that could make the jets of matter that come out of the quasar and the radio galaxies
- 00:54:19in ways that are not really understood.
- 00:54:22We don't have a real picture why there are jets of radio waves, matter emitting radio waves in galaxies
- 00:54:30there are galaxies which great jets coming out with big clouds of matter on each side which are emitting radio waves
- 00:54:37so there's some kind of a source in there
- 00:54:39it sort of gets wound up and shoots these jets of matter out with tremendous energy
- 00:54:45And it's guessed that maybe it's a black hole somehow or other
- 00:54:50and the somehow or other is the challenge of the imagination
- 00:54:54Which has not yet been answered. by anybody, with any great confidence.
- 00:55:05You ask me if an ordinary person, by studying hard, would get to be able to imagine these things, like I imagine
- 00:55:12Of course! I was an ordinary person who had studied hard.
- 00:55:16There are no miracle people.
- 00:55:18It just happen they got interested in these things and they learned all these stuffs.
- 00:55:24There are just people
- 00:55:25There's no talent, special, miracle ability to understand quantum mechanics or a miracle ability to imagine electromagnetic fields
- 00:55:36that comes without practicing and reading and learning and study
- 00:55:40so if you say it take an ordinary person who's willing to devote a great deal of time
- 00:55:45and study and work and thinking and mathematics and time, then he has become a scientist.
- 00:55:55When I'm actually doing my own things
- 00:55:58and working in a high, deep and esoteric stuff that I worry about
- 00:56:04I don't think I can describe very well what it's like
- 00:56:10First of all, it's like asking a centipede which leg comes after which
- 00:56:14it happens quickly and I'm not exactly sure what flashes and stuff go in the head
- 00:56:19But I know it's a crazy mixture of partial equations, partial solving in equations,
- 00:56:24then having some sort of picture of what is happening that the equation is saying it's happening
- 00:56:29but they're not that well separated as the words I'm using and it's a kind of a nut nutty thing
- 00:56:36it's very hard to describe, and I don't know that it does any good to describe
- 00:56:40And there's something that struck me, it's very curious:
- 00:56:45I suspect that what goes on in every man's head might be very very different, the actual imagery or semi-imagery which comes
- 00:56:57and when we are talking to each other at these high and complicated levels
- 00:57:00and we think we are speaking very well, that we are communicating
- 00:57:06but what we are really doing is having a some kind of big translation scheme going on
- 00:57:10for translating what this fellow says into our images, which are very different.
- 00:57:15I found that out because in the very lowest level I wouldn't go into much details but I got interested in...
- 00:57:25Well I was doing some experiments and I was trying to figure out something about our time sense
- 00:57:31and so what I would do is trying to count to a minute
- 00:57:35actually say I'd count to 48 then it would be one minute
- 00:57:39so I calibrate myself and I would count a minute in 48
- 00:57:42think I was counting seconds but it's close enough
- 00:57:44and then it turns out if you repeat that you can do very accurately
- 00:57:48when you get to 48 or 47 or 49, not far off, you're very close to a minute.
- 00:57:54And I was trying to find out what affected that time sense
- 00:57:57and whether I could do anything at the same time I was counting
- 00:58:01and I found that I could do many things I could, there were some things that not
- 00:58:08For example, I had great difficulty…
- 00:58:10I was in the university, I had to get my laundry ready, and I was putting the socks out
- 00:58:19and I had to make a list "how many socks", there were something like 6 or 8 socks and I couldn't count them
- 00:58:24because the counting machine was being used, and I couldn't count them
- 00:58:27until I found that I could put them in a pattern and recognize the number
- 00:58:31and so I learned a way after practicing
- 00:58:33by which I could count the line of type in a newspaper and see them in groups
- 00:58:37three, three, three, three, one that's a group of ten, three, three, three, one
- 00:58:40without saying the numbers just seeing the groupings
- 00:58:42I could therefore count the line of types I was practicing in the newspaper
- 00:58:46the same time I was counting internally the seconds
- 00:58:49so I could do this fantastic trick of saying
- 00:58:53"forty-eight, that's one minute and there are sixty seven lines of type" you see!
- 00:58:58It was quite wonderful and I discovered many things I could read while I was..
- 00:59:05no, excuse me, yes, I could read perfectly alright while I was counting and get an idea of what it was about
- 00:59:14But I couldn't speak, I couldn’t say anything.
- 00:59:17Because of course I was sort of trying to speak to myself, inside, I would say "one, two, three" or sort of in the head.
- 00:59:24Then I went down to the breakfast, and there was John Tukey was a mathematician at Princeton in the same time
- 00:59:33and we had many discussions, and I was telling him about these experiments and what I could do
- 00:59:37and he says "that's absurd!" he says
- 00:59:40He said "I don't see why you have any difficulty talking whatsoever,
- 00:59:44And I can't possibly believe that you could read"
- 00:59:47so I couldn't believe all this but we calibrated him
- 00:59:50it was 52 for him to get to 60 seconds or whatever I don't remember the numbers now
- 00:59:55and then he said "alright, what do you want me to say?
- 00:59:58Mary had a little lamb. I can speak about anything, blah blah blah, blah blah,
- 01:00:0252! that's one minute". He was right. And I couldn't possibly do that
- 01:00:07And he wanted me to read, because he couldn’t possibly believe it.
- 01:00:09and then we compared note, and it turned out that when he thought of counting
- 01:00:13what he did inside his head when he counted was he saw a tape with numbers it went "clink, clink clink"
- 01:00:20the tape would change with numbers printed on it, he could see
- 01:00:23well since it's sort of an optical system that he was using, and not voice.
- 01:00:28He could speak as much as he wanted but if he had to read, then he couldn't look at his clock!
- 01:00:33Whereas for me it was in the other way.
- 01:00:34And that's where I discovered, at least in this very simple operation of counting
- 01:00:39the great difference in what goes on in the head when people think they are doing the same thing
- 01:00:46And so it struck me therefore, if that is already true at the most elementary level
- 01:00:51That when we learn mathematics and Bessel functions, and the exponential and the electric field and all these things
- 01:00:59that the imageries and the method by which we are storing it all and the way we think about it
- 01:01:05could be really, if we get to each other's head, entirely different
- 01:01:09And in fact, while somebody sometimes has a great deal of difficulty to understanding a point which you see as obvious, and vice versa
- 01:01:17it's maybe because it's a little hard to translate what you just said into his particular framework and so on
- 01:01:22Now I'm talking like a psychologist, and you know I know nothing about this!
- 01:01:29Suppose that little things behaved very differently that anything that was big, anything that you're familiar with
- 01:01:39because you see as the animal evolves and so on, as brain evolves
- 01:01:42it gets used to handling the brain is designed for ordinary circumstances
- 01:01:49but if the gut particles in the deep inner workings where by some other rules and some other characters
- 01:01:55they behave differently they were very different than anything on a large scale
- 01:02:00then there would some kind of difficulty in understanding and imagining reality.
- 01:02:05And that difficulty, we are in.
- 01:02:09The behavior of things on the small scale is so fantastic! It is so wonderfully different!
- 01:02:16so marvelously different that ANYTHING that behaves on a large scale.
- 01:02:20You said "electrons act like wave", no they don't exactly,
- 01:02:24"they act like particles", no, they don't exactly,
- 01:02:26"they act like a kind of a fog around the nucleus", no they don't exactly.
- 01:02:31And if you want to get a clear, sharp picture of an atom, so that you can tell exactly how it's going to behave correctly
- 01:02:40and have a good image in other words, really good image of reality
- 01:02:44I don't know how to do it. Because that image has to be mathematic:
- 01:02:49we have a mathematical expression, a strange mathematics, I don't understand how it is
- 01:02:53but we can write mathematical expressions and calculate what the thing is going to do
- 01:02:59without actually being able to picture it
- 01:03:02It would something like a computer in which you put certain numbers in
- 01:03:05and you have a formula for what time the car will arrive at different destination
- 01:03:09and the thing does the arithmetic to figure out what time the car arrives at the different destinations
- 01:03:14but cannot picture the car. It is just doing the arithmetic
- 01:03:18So we know how to do the arithmetic, but we cannot picture the car
- 01:03:23It's not a 100% because for certain approximate situations, certain kind of approximate pictures work
- 01:03:29that it's simply a fog around the nucleus that when you squeeze it, it repels you
- 01:03:34it's very good for understanding the stiffness of certain material
- 01:03:38that it's a wave which does this and that is very good for some other phenomena alright
- 01:03:43So when you're working with certain particular aspects of the behavior of atoms
- 01:03:48for instance when I was talking about temperature and so forth, that it's just little balls
- 01:03:53it's good enough and it gives a very nice picture of temperature
- 01:03:56but if you ask more specific question and you get down to questions like
- 01:04:00"how is that when you cool helium down, even to absolute zero where it's not supposed to be any motion
- 01:04:07it's a perfect fluid and it has no resistance and it flows perfectly, and it isn't freezing"
- 01:04:13Well if you want to get a picture of atoms as all of that in it, I can't do it
- 01:04:17But I can explain why the helium behaves as it does, by taking my equations
- 01:04:23and seeing that the consequences of them is that the helium would behave as it is observed to behave
- 01:04:28So we know that we have the theory right, but we haven't got the pictures that would go with the theory
- 01:04:34And it's that because we haven't caught on the right picture
- 01:04:40or it's because there aren't any right pictures for people who have to make pictures out of things that are familiar to them
- 01:04:50Well let's suppose it's the last one, that there's no right picture in terms of things that are familiar to them
- 01:04:56Is it possible then to develop a familiarity with those things that are not familiar on hand, by studying
- 01:05:05by learning the properties of atoms and quantum mechanics, by practicing with the equations
- 01:05:10until it becomes a kind of second nature
- 01:05:12just like it's a second nature to know that two balls came towards each other, they smash into bits
- 01:05:18You don't say "the two balls when they come toward each other turn blue". You know what they do
- 01:05:24So the question is whether you can get to know what things do without... better that we do today
- 01:05:32as the generations develop, will they invent ways of teaching so that the new people will learn tricky ways in looking at things
- 01:05:43and be so trained, so well trained, that they won't have our troubles, with the atom picturing.
- 01:05:52There's still a school of thought that cannot believe that the atomic behaviors is so different than large scale behaviors
- 01:06:02I think that's a deep prejudice, it's a prejudice of being so used to large scale behaviors
- 01:06:06and they're always seeking to find to waiting for the day that we discover
- 01:06:11underneath the quantum mechanics there's some mundane, ordinary balls hitting or particles moving and so on
- 01:06:20I think they're gonna be defeated
- 01:06:22I think Nature's imagination is so much greater than man's, she's never gonna let us relax!
- science
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- atoms
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- physics
- heat
- neutron stars
- black holes
- quasars
- electromagnetism