Greatest Discoveries with Bill Nye Astronomy

00:41:42
https://www.youtube.com/watch?v=cMYbGYVh5ys

Résumé

TLDRThe presentation covers 13 milestones in astronomical discoveries, beginning with ancient Mesopotamian records and culminating in modern advancements like the detection of exoplanets and dark energy. It discusses the transition from the Earth-centered model to the heliocentric model proposed by Copernicus, the adjustments made by Kepler regarding planetary motion, and Galileo's telescope observations. The narrative emphasizes significant figures such as Einstein and Hubble, the theoretical implications of dark energy, and the ongoing quest to understand the expanding universe and the possibility of extraterrestrial life.

A retenir

  • 🌟 Humanity's quest for understanding the cosmos has spanned thousands of years.
  • 📜 The Mesopotamians recorded celestial movements on clay tablets.
  • ☀️ Copernicus introduced the heliocentric model, revolutionizing astronomy.
  • 🔭 Galileo's telescope revealed moons orbiting Jupiter, supporting the heliocentric theory.
  • 📏 Kepler determined that planetary orbits are elliptical, not circular.
  • 🔭 Carl Jansky's work led to the discovery of black holes via radio astronomy.
  • 💥 The Big Bang theory explains the universe's expansion from a hot, dense state.
  • 🌌 Edwin Hubble established that the universe is indeed expanding.
  • 🔍 Exoplanets are found using Doppler wobbles of stars indicating gravitational pulls.
  • ⚡ Dark energy is a mysterious force accelerating the universe's expansion.

Chronologie

  • 00:00:00 - 00:05:00

    The presentation introduces the evolution of human understanding of the cosmos, emphasizing how advancements in astronomical observation have revealed a wondrous universe. It highlights the significance of ancient astronomers, particularly the Mesopotamians, who documented celestial movements and contributed foundational knowledge to future astronomers.

  • 00:05:00 - 00:10:00

    The narrative transitions to the Greek astronomers who built upon Mesopotamian records, resulting in a geocentric view that dominated for centuries, reinforcing the importance of historical observations in shaping astronomical theories.

  • 00:10:00 - 00:15:00

    The story then focuses on Nicholas Copernicus, who proposed a heliocentric model of the solar system. His revolutionary insights laid the groundwork for modern astronomy, challenging the geocentric perspective and positioning the Earth as just another planet orbiting the sun.

  • 00:15:00 - 00:20:00

    Galileo's innovations with the telescope led to significant discoveries that supported Copernicus' theory, including the observation of moons orbiting Jupiter. This demonstrated the validity of heliocentrism and the vital role of empirical evidence in scientific progress.

  • 00:20:00 - 00:25:00

    The narrative discusses Edmund Halley and his prediction of the periodic return of Halley's Comet, showcasing the shift from superstition to a scientific understanding of celestial events, exemplified by predictable comet trajectories.

  • 00:25:00 - 00:30:00

    William Herschel's discovery of Uranus and the vastness of the Milky Way further reshaped humanity's view of the cosmos, revealing that our solar system is part of a much larger universe filled with numerous stars and galaxies.

  • 00:30:00 - 00:35:00

    The discussion then introduces Albert Einstein and his theory of general relativity, which altered perceptions of gravity and space. Einstein's groundbreaking ideas explained phenomena that Newton's laws couldn't, leading to a deeper understanding of the universe's structure.

  • 00:35:00 - 00:41:42

    Finally, modern discoveries, such as the expansion of the universe and dark energy, highlight the ongoing quest to unravel cosmic mysteries, demonstrating humanity's relentless pursuit of knowledge and the need for advanced observations to comprehend our place in the cosmos.

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Carte mentale

Vidéo Q&R

  • What is the significance of the Venus tablet of Ammida?

    It contains the earliest record of a planet's motion.

  • Who proposed the heliocentric model of the solar system?

    Nicholas Copernicus proposed that the Sun is at the center of the solar system.

  • What did Galileo discover with the telescope?

    Galileo observed moons orbiting Jupiter, providing evidence against the Earth-centered model.

  • What are gamma-ray bursts?

    They are high-energy explosions in distant galaxies, considered potential causes for extinction events.

  • What is dark energy?

    It is a mysterious force driving the accelerated expansion of the universe.

  • Who was Edwin Hubble?

    An astronomer who discovered that the universe is expanding and identified distant galaxies.

  • What was Kepler's contribution to astronomy?

    He formulated the laws of planetary motion and revealed that planets move in elliptical orbits.

  • What did Carl Jansky discover?

    He identified a supermassive black hole at the center of the Milky Way, marking the birth of radio astronomy.

  • What was the Big Bang theory?

    It suggests that the universe began from an extremely hot and dense state and has been expanding ever since.

  • What are exoplanets?

    Planets that orbit stars outside our solar system.

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    [Music]
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    the following presentation is brought to
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    you by Discovery Education leading the
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    world of digital and video
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    learning Discovery Education connect to
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    a world of
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    learning for most of human history the
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    only light we knew came from the sky by
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    day the Sun by Night an uncountable
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    number of stars now from the beginning
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    our ancestors believed that the sun and
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    the stars were Heavenly out of this
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    world and they were right we've been
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    watching the sky for thousands of years
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    but until recently we couldn't see well
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    enough to understand our connection to
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    the cosmos but now our astronomical
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    Vision has sharpened we can see farther
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    and clearer we can observe objects that
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    are invisible to human eyes our
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    increasingly improving Vision has
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    allowed us to make great discoveries
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    revealing an astonishing and wonderful
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    Universe what follows are 13 of the
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    greatest discoveries in astronomy
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    [Music]
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    [Music]
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    our first great discovery happened over
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    centuries as the first humans looked
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    carefully at the sky in places like this
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    the empty cloudless deserts of the
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    American
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    southwest the Middle
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    East Africa and South
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    America of these ancient astronomers the
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    most important were the
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    [Music]
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    Mesopotamians they considered the
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    objects in the sky gods and built giant
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    Towers so they could record the rising
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    and setting of the Sun the Moon and the
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    stars for more than a thousand years
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    they used clay tablets to record what
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    they
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    saw to find out more I paid a visit to
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    Professor of astronomy Owen Gingrich
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    ason here for example is one of these
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    clay tablets have a read yeah uh These
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    Guys these people wrote small yes I was
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    perfectly amazed when somebody came into
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    my office and picked it up and actually
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    started reading it so what language is
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    this I think this is in
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    Babylonian hundreds of these tablets
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    were
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    unburied among these hundreds of tablets
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    is a tablet called the Venus tablet of
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    amoda and this tablet contains the
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    motion of the planet Venus that's the
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    earliest record we have of a planet
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    moving and after the Mesopotamians made
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    the first records it was the Greeks who
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    took the next
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    step some of the Greek astronomers made
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    a field trip out to Mesopotamia to find
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    out what had been going on there and
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    they seemed to have brought back some
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    systematic records so that ultimately it
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    gave the basis for making a mathematical
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    theory of the motion of the
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    planets from their observations the
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    Greeks developed a vision of the solar
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    system that was stand for some 2,000
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    years that the planets move revolving
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    around the earth it would take our next
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    great discovery to set the record
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    [Music]
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    straight the year is
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    1543 a 70-year-old man is dying his name
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    Nicholas capern
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    a doctor and lawyer by trade but for
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    nearly 40 years he was also an amateur
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    astronomer a Pursuit that had led him to
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    challenge one of the most fundamental
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    and sacred beliefs of his
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    time as a young man kernus had studied
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    the heavens and found that the Greek's
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    Earth centered system failed when it
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    came to predicting planetary
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    motion now those he began to wonder if
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    the Earth itself
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    moved
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    but here is cernus is
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    idea with the Sun as the center the sun
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    is the center and now suddenly all the
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    planets are going always the same way
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    around they're not stopping cernus
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    realized that the movements of the
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    planets were better explained if the sun
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    were at the center of the solar system
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    and the Earth circled it like an
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    ordinary Planet it was a revolution
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    Insight despite any evidence that the
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    Earth was moving he came up with this
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    book which uh uh gives his new Theory
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    this idea this this book changed the
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    world yes because it made the Earth a
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    planet and it fixed the sun in the
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    center if you don't have that blueprint
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    you don't March ahead to the physics the
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    physics of the Cosmos as it happened the
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    final Pages which were just these here
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    in the front of the book came to him on
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    the very day he died I suspect I mean he
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    was lying there partially paralyzed from
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    a stroke he was probably just hanging in
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    there till he could make sure that it
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    was done
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    [Music]
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    everyone from the Greeks to cernic
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    assumed the orbits of the planets had to
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    be
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    circular but in
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    1571 German mathematician Johannes
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    Kepler shattered that assumption with
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    our next great
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    discovery lacking calculus Kepler
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    improvised ways to compute the circular
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    orbit of
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    [Music]
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    Mars the work was teach
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    keper wrote that he was almost driven to
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    Madness considering and calculating the
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    matter his calculations began to reveal
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    that the accepted notion of planets
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    moving in circles simply did not
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    work then a new idea came to him Kepler
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    realized somehow the sun had to be
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    driving the planets in some way that he
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    didn't fully understand
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    and to get a self-consistent picture he
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    found that an ellipse was the path
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    rather than a
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    circle with this breakthrough Kea
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    devised the first method for accurately
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    predicting the movement of the planets
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    and stars across the sky when his tables
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    predicted the planet Mercury to pass
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    across the front of the Sun and nobody
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    else's tables were
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    close that was dramatic proof of the
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    accuracy of his
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    astronomy it linked the Motions of the
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    planets solidly to the sun this was a
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    very important point to help stress the
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    idea that the capern sun centered system
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    really had physical
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    significance and in the case of our next
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    great discovery his determination led
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    him to revolutionize our knowledge of
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    the solar system
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    the year is 1609 and Galileo is
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    fascinated with a new invention called a
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    telescope essentially it was a toy out
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    of a carnival when Galileo heard about
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    it he went to work making
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    one he perfected it and essentially
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    converted a toy into a scientific
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    instrument Galileo turned his telescope
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    Skyward
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    and was the first to see the mountains
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    on the
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    moon and the star clusters of the Milky
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    Way then an extraordinary
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    site a group of four small Bright Stars
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    arranged around the planet
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    [Music]
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    Jupiter we have the manuscript of his
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    first week of observations and it it's
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    wonderful because you
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    see him gradually coming to the
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    conclusion that these little stars are
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    carried along with
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    Jupiter this was the moment of
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    Discovery Galileo realized that the
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    stars were actually four moons orbiting
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    Jupiter he had the Insight that these
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    moving dots were orbiting a planet I
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    sometimes say he invented the satellites
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    and you say wait a minute they were
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    there how could he have invented them he
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    invented the idea that they were going
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    around the
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    planet here was proof that cernic us was
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    right about the structure of the solar
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    system if moons could orbit Jupiter then
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    the Earth could orbit the Sun and
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    Galileo's Discovery demonstrated that
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    knowledge in astronomy can only be
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    Advanced by actual observation a theory
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    can only be viable when it's supported
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    by the facts just like our next great
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    [Music]
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    discovery for centuries comets had been
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    considered harbingers of
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    Evil by the end of the Middle Ages a
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    comet's appearance invoked fear and
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    Terror
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    but Renaissance scientist Edmund Hy like
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    Galileo was interested in facts not
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    Superstition in 1695 he began searching
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    for records of ancient and recent Comet
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    sightings he found 24 comets whose
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    passage across the sky had been recorded
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    with enough detail to allow him to
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    roughly plot their orbits to his
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    surprise he found that three of the
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    Comets seemed to follow the same
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    approximate orbit circling the Sun every
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    76
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    years on that basis he figured okay this
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    is a comet that's going to be back in
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    another 76 years he figured out that the
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    three comets were actually the same
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    Comet the same
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    Comet hie was so certain of the comet's
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    orbit that he made a bold
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    [Music]
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    prediction he said the comet would
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    return in the year 1758
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    and guess what it was the Comet came
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    back unfortunately hie was no longer
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    alive to savor his
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    Discovery since then hi's Comet as it's
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    known has been greeted three more times
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    by excited skywatchers across the
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    globe no longer a harbinger of evil
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    Hal's Comet became a milestone Discovery
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    in the history of astronomy replacing a
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    superstitious belief with a rational
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    scientific understanding of the physical
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    [Music]
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    Universe in the 18th century William
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    herel was a classically trained
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    musician whose love of astronomy led him
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    to give up music and turn his attention
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    to the heavens
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    thus setting the stage for our next
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    great
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    discovery when he discovered the price
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    of a refracting telescope which was
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    beyond his means he decided to make his
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    own and he became the most fabulous and
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    successful telescope builder of that
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    period he used his telescopes to
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    methodically survey the sky cataloging
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    what he
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    saw as he he was searching the sky he
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    came across an object that looked a
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    little bit different turned out to be a
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    new planet oh wow and what planet was
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    that that was the next planet Beyond
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    Saturn the planet
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    Uranus Uranus was the first new planet
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    to be identified in more than 3500
  • 00:13:52
    years but finding a new planet was
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    nothing compared to Hershel's larger
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    goal
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    he built a powerful 20ft telescope then
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    divided the sky into equal sections and
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    began to systematically count the stars
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    in each
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    field it was a painstaking Monumental
  • 00:14:13
    task slowly Hershel's star count began
  • 00:14:16
    to reveal something
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    extraordinary the Milky Way was much
  • 00:14:21
    larger than anyone
  • 00:14:22
    knew it was a gigantic disc of
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    stars some of its fields were jam-packed
  • 00:14:30
    one showed more than a quarter of a
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    million stars
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    alone other fields farther away were
  • 00:14:38
    practically
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    empty Hershel's Discovery was a
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    revelation this is a a reasonable model
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    of the Milky Way as we know it now but
  • 00:14:51
    hersel was only looking at an
  • 00:14:53
    area about this big is that right what
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    herel was seeing was a small range like
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    this uh maybe that big uh so it was
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    really a small part of the entire Milky
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    Way But even that small part
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    significantly changed the study of
  • 00:15:14
    astronomy Hershel's Discovery revealed
  • 00:15:16
    that our solar system was just an island
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    in a deep and expansive universe
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    [Music]
  • 00:15:30
    thanks to the musings of an obscure
  • 00:15:32
    clerk working in the Swiss patent office
  • 00:15:35
    our next great discovery revealed that
  • 00:15:37
    the universe is a strange mysterious
  • 00:15:40
    place every Century Mercury's parhelion
  • 00:15:44
    Advance slightly a change that Newton's
  • 00:15:47
    equations could not account
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    for in a bold and startling Move Young
  • 00:15:56
    Einstein proposed his own Theory to
  • 00:15:59
    explain the puzzle of Mercury's orbit
  • 00:16:01
    and in the process developed a theory
  • 00:16:03
    that refined Newton's laws of
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    [Music]
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    gravity miio Kaku is a theoretical
  • 00:16:11
    physicist at the City University of New
  • 00:16:15
    York Newton says that gravity travels
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    instantaneously throughout space and
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    that's where Einstein thought there was
  • 00:16:22
    a weakness in Newton's theory he wanted
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    a theory that could explain gravity he
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    wanted a theory that could explain
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    acceleration and zigzag and circular
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    motion there has to be waves gravity
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    waves it takes time for Gravity to work
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    its magic to propagate to propagate so
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    if the Su were to disappear it would
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    take eight minutes for us to know about
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    that fact even gravity travels at the
  • 00:16:46
    speed of light Einstein needed a new
  • 00:16:49
    picture to explain that and that picture
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    was curv space that space itself has
  • 00:16:55
    curved and that's why objects move
  • 00:17:00
    Einstein believed that his concept of
  • 00:17:02
    curved space was responsible for
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    shifting Mercury's
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    orbit Einstein called his idea the
  • 00:17:09
    theory of general
  • 00:17:13
    relativity imagine a trampoline net and
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    place a bowling ball in the middle of a
  • 00:17:18
    trampoline net the bowling ball sinks
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    into the trampoline net and now shoot a
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    marble a marble around the trampoline
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    net the marble will orbit orbit around
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    the bowling ball now from a distance
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    looking down Newton would say that there
  • 00:17:33
    is a force an instantaneous invisible
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    force pulling pulling the marble down to
  • 00:17:40
    the bowling ball but Einstein would say
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    there's no Force there's no pull it's
  • 00:17:46
    just a trampoline net and why is the
  • 00:17:48
    marble orbiting around the bowling ball
  • 00:17:51
    because a trampoline net is pushing the
  • 00:17:54
    marble therefore why am I sitting on
  • 00:17:56
    this chair not because gravity pulls you
  • 00:17:59
    to the ground it's because space pushes
  • 00:18:01
    me down toward the planet
  • 00:18:04
    Earth the idea that space itself was
  • 00:18:07
    warped by mass was too strange for many
  • 00:18:09
    to accept an approaching solar eclipse
  • 00:18:12
    gave scientists the perfect opportunity
  • 00:18:15
    to put Einstein's new Theory to the
  • 00:18:20
    test photographs were taken of the
  • 00:18:22
    background Stars before the eclipse and
  • 00:18:25
    then afterwards these pictures were then
  • 00:18:28
    compared with photos taken during the
  • 00:18:31
    eclipse the photo showed that the
  • 00:18:33
    positions of the stars in the eclipse
  • 00:18:35
    photo shifted slightly inward bending as
  • 00:18:38
    the light from the Stars past the sun's
  • 00:18:41
    gravitational
  • 00:18:43
    field Einstein's theory of general
  • 00:18:45
    relativity was
  • 00:18:47
    right his great discovery rocked the
  • 00:18:51
    world general relativity strikes a deep
  • 00:18:54
    emotional cord in anyone who's ever
  • 00:18:57
    looked at these equations
  • 00:18:59
    these equations are one inch long and
  • 00:19:01
    yet they answer these Eternal questions
  • 00:19:04
    that have dogged us ever since we first
  • 00:19:06
    looked in the night sky and ask
  • 00:19:08
    ourselves the question what's it all
  • 00:19:19
    mean general relativity had shown that
  • 00:19:22
    space was weirder than anyone could
  • 00:19:24
    imagine anyone but Einstein that
  • 00:19:27
    is to gain a clearer understanding of
  • 00:19:30
    this strange Universe astronomers needed
  • 00:19:32
    more observational
  • 00:19:34
    data and that required larger more
  • 00:19:37
    powerful
  • 00:19:38
    telescopes like the one that led to our
  • 00:19:41
    next great
  • 00:19:45
    [Music]
  • 00:19:46
    discovery when the hersel had finished
  • 00:19:48
    their survey of the heavens in the 1830s
  • 00:19:51
    they had cataloged thousands of these
  • 00:19:53
    beautiful but hazy objects then called
  • 00:19:56
    White nebuli
  • 00:20:01
    at the time no one knew whether they
  • 00:20:03
    were part of our
  • 00:20:06
    galaxy or distant Island universes like
  • 00:20:09
    the Milky
  • 00:20:12
    [Music]
  • 00:20:15
    Way in
  • 00:20:17
    1924 astronomer Edwin Hubble was
  • 00:20:20
    studying the stars in several of these
  • 00:20:22
    nebuli using a 100in reflector telescope
  • 00:20:25
    at the Mount Wilson Observatory in
  • 00:20:27
    California
  • 00:20:28
    [Music]
  • 00:20:32
    the telescope enabled Hubble to estimate
  • 00:20:35
    that the galaxies were routinely many
  • 00:20:37
    hundreds of thousands even millions of
  • 00:20:40
    light years
  • 00:20:41
    away here were objects as huge and as
  • 00:20:45
    populated with stars as our very own
  • 00:20:47
    Milky Way
  • 00:20:48
    galaxy which is why we today call White
  • 00:20:51
    nebuli
  • 00:20:53
    [Music]
  • 00:20:55
    galaxies the more Hubble studied these
  • 00:20:58
    galaxies the more he became intrigued at
  • 00:21:01
    the time scientists knew that a beam of
  • 00:21:03
    light from a star appears as a different
  • 00:21:06
    color on the
  • 00:21:08
    Spectrum the color changed according to
  • 00:21:10
    the motion of the star a shift toward
  • 00:21:13
    the blue end of the spectrum meant the
  • 00:21:15
    star was moving closer to
  • 00:21:17
    Earth a red shift meant it was moving
  • 00:21:20
    away the amount of the color shift also
  • 00:21:23
    revealed the speed of that
  • 00:21:26
    movement Hubble found that when he
  • 00:21:28
    measured the distance of a galaxy its
  • 00:21:31
    Spectrum almost always was shifting to
  • 00:21:33
    the
  • 00:21:34
    red and something else the farther the
  • 00:21:38
    distance the greater the red
  • 00:21:41
    shift in other words the universe was
  • 00:21:45
    expanding it was an astonishing
  • 00:21:48
    Discovery with profound
  • 00:21:50
    implications measuring backwards from
  • 00:21:53
    the expansion scientists found that the
  • 00:21:55
    Universe appeared to have a cataclysmic
  • 00:21:57
    beginning but one astronomer labeled the
  • 00:22:00
    Big
  • 00:22:08
    [Music]
  • 00:22:14
    Bang just 3 years after Hubble
  • 00:22:16
    discovered the expanding Universe our
  • 00:22:19
    next great discovery revealed a
  • 00:22:20
    mysterious object hidden behind the dust
  • 00:22:23
    at the center of the Milky Way and gave
  • 00:22:25
    birth to a whole new branch of astronomy
  • 00:22:28
    using wavelengths invisible to the human
  • 00:22:33
    eye in 1930 Carl jansy was a 25-year-old
  • 00:22:38
    physicist working for the Bell
  • 00:22:39
    Laboratories in Hell New
  • 00:22:44
    Jersey jansky's job was to identify the
  • 00:22:47
    kinds of interference occurring at the
  • 00:22:49
    15 M wavelength then used for ship to
  • 00:22:52
    Shore and transatlantic
  • 00:22:55
    communication after spending more than a
  • 00:22:57
    year recording data jansy decided there
  • 00:23:00
    were three forms of stat inside the
  • 00:23:03
    solar
  • 00:23:06
    system eventually jansy pinpointed its
  • 00:23:09
    location as somewhere in the region of
  • 00:23:11
    the constellation
  • 00:23:13
    Sagittarius he believed he had
  • 00:23:15
    discovered an unknown Interstellar
  • 00:23:16
    object at the center of the
  • 00:23:19
    Galaxy and he was
  • 00:23:22
    right later astronomers confirmed that
  • 00:23:25
    Jans skid discovered a super massive
  • 00:23:27
    black hole equal in Mass to 3 Million
  • 00:23:32
    Suns perhaps even more significant he
  • 00:23:36
    was the first human to look at the
  • 00:23:37
    universe using radio astronomy a whole
  • 00:23:40
    new way to study the
  • 00:23:43
    sky it was a landmark
  • 00:23:46
    Discovery jansky had proved that the sky
  • 00:23:49
    does not merely Sparkle with the gentle
  • 00:23:51
    glow of Starlight hidden out there are
  • 00:23:54
    many strange objects many light years
  • 00:23:56
    away that actually radiate more energy
  • 00:23:59
    than whole galaxies like quazars and
  • 00:24:02
    pulsars dead stars spinning madly with
  • 00:24:06
    masses so dense that a single teaspoon
  • 00:24:08
    would weigh millions of
  • 00:24:13
    tons before astronomers could even begin
  • 00:24:16
    to understand the life and death of
  • 00:24:18
    stars new telescopes would have to be
  • 00:24:21
    built that could look at the sky in many
  • 00:24:23
    different wavelengths before that could
  • 00:24:25
    happen though radio astronomy produced
  • 00:24:28
    another great discovery that although
  • 00:24:31
    predicted was as unexpected by its
  • 00:24:33
    discoverers as jansky had been and once
  • 00:24:36
    again it happened at Bell labs in Hell
  • 00:24:39
    New
  • 00:24:42
    [Music]
  • 00:24:48
    Jersey in 1964 Bell Labs had this spare
  • 00:24:52
    20ft microwave antenna sitting
  • 00:24:55
    dormant rather than destroy it the lab
  • 00:24:58
    decided to let astronomers use it for
  • 00:25:01
    research two physicists 31-year-old Arno
  • 00:25:05
    penus and 28-year-old Robert Wilson
  • 00:25:08
    decided to use the antenna for measuring
  • 00:25:11
    the temperature of the gas Halo
  • 00:25:13
    surrounding the Milky Way
  • 00:25:17
    Galaxy what happened next is one of the
  • 00:25:19
    most exciting discoveries in modern
  • 00:25:21
    [Music]
  • 00:25:24
    astronomy hi Dr Wilson and I came to
  • 00:25:28
    cabs to get the story firsthand from
  • 00:25:30
    Robert Wilson himself two of us Arnold
  • 00:25:34
    penus and I had just come to Bell Labs
  • 00:25:37
    from graduate school and we were going
  • 00:25:39
    to measure radiation from the Milky Way
  • 00:25:42
    and that's where this antenna really fit
  • 00:25:44
    in because we could reject the radiation
  • 00:25:47
    from the earth and what was left is uh
  • 00:25:51
    what's coming from the
  • 00:25:54
    sky we were only getting about 2 de from
  • 00:25:57
    the Earth's atmosphere
  • 00:25:59
    maybe pick up one degree from the walls
  • 00:26:01
    of this thing but when we first turned
  • 00:26:03
    it on it was about twice that it was 7°
  • 00:26:08
    and this just wasn't right something
  • 00:26:10
    from the earth must be in our
  • 00:26:13
    instrumentation we of course are on a
  • 00:26:15
    hill here that overlooks New York City
  • 00:26:18
    we had the ideal instrument for checking
  • 00:26:20
    on that though we merely turn it down to
  • 00:26:22
    the Horizon scan the Horizon and bl and
  • 00:26:26
    behold nothing particular extra
  • 00:26:30
    there was a pair of pigeons that lived
  • 00:26:32
    in here and of course it was covered
  • 00:26:34
    with white pigeon droppings so we
  • 00:26:37
    thought well maybe the pigeon droppings
  • 00:26:38
    are doing more than we think AR and I
  • 00:26:42
    got up in here and we cleaned all the
  • 00:26:44
    pigeon droppings
  • 00:26:46
    out got rid of the pigeons what happen
  • 00:26:49
    how'd you get rid of the pigeons well
  • 00:26:50
    first we put them in the company mail
  • 00:26:52
    and sent them as far as we could which
  • 00:26:54
    was riny New Jersey uh to a pigeon
  • 00:26:56
    fancier there who said these are junk
  • 00:26:58
    pigeons and let them go a couple of days
  • 00:27:00
    later they were Back 40 miles away they
  • 00:27:03
    came back yes so then our technician
  • 00:27:05
    brought in a shotgun and then how did
  • 00:27:08
    that
  • 00:27:09
    work I wasn't here I didn't see it but
  • 00:27:12
    basically it didn't didn't solve our
  • 00:27:14
    problem we still had an extra three four
  • 00:27:19
    degrees we were really beginning to be
  • 00:27:21
    perplexed because you know we believe in
  • 00:27:23
    physics it's coming from somewhere we
  • 00:27:26
    can calculate what the horn is doing
  • 00:27:28
    except for this excess
  • 00:27:32
    noise at the time that penus and Wilson
  • 00:27:35
    detected the radiostatic there were two
  • 00:27:38
    competing theories about the origin of
  • 00:27:40
    the universe there was the Big Bang
  • 00:27:42
    Theory which hubbles expanding Universe
  • 00:27:45
    supported and there was the steady state
  • 00:27:48
    Theory which proposed that the universe
  • 00:27:50
    is timeless with no beginning or end
  • 00:27:53
    expanding forever
  • 00:27:56
    [Music]
  • 00:27:58
    when a friend heard what penus and
  • 00:28:00
    Wilson had found he suggested they get
  • 00:28:02
    in touch with some cosmologists at
  • 00:28:05
    Princeton University who were Advocates
  • 00:28:07
    of The Big Bang Theory they believ that
  • 00:28:09
    a big bang would have left a faint
  • 00:28:11
    thermal Afterglow in the universe traces
  • 00:28:14
    of heat from the Roar of the bang itself
  • 00:28:16
    detectable across the entire
  • 00:28:20
    sky and they were about to conduct
  • 00:28:22
    research in hopes of measuring that
  • 00:28:26
    Afterglow we invited the them over they
  • 00:28:29
    came over and looked at what we had done
  • 00:28:31
    and immediately agreed that we had
  • 00:28:33
    measured what they were setting out to
  • 00:28:35
    do so what does your Discovery mean well
  • 00:28:38
    it means that we live in a big bang
  • 00:28:41
    universe and uh that we're seeing the
  • 00:28:43
    radiation from 300,000 years after the
  • 00:28:46
    big bang in many cases when there's a
  • 00:28:48
    paradigm ship in science it takes a
  • 00:28:50
    generation before people really accept
  • 00:28:52
    it but in this case I think the world
  • 00:28:55
    was ready for it Human Society is always
  • 00:28:58
    worried about where they came from they
  • 00:29:01
    their religious stories in every
  • 00:29:03
    civilization that's ever been found and
  • 00:29:05
    I think we have a definitive answer that
  • 00:29:08
    we came out of a big
  • 00:29:15
    [Music]
  • 00:29:19
    bang the coming of the Space Age ushered
  • 00:29:22
    in a golden age of astronomy that is
  • 00:29:25
    still going on today that golden age
  • 00:29:28
    began strangely enough not in space but
  • 00:29:31
    with a turning point in Cold War
  • 00:29:33
    relations that also contributed to our
  • 00:29:36
    next great
  • 00:29:39
    discovery in the 1960s despite a nuclear
  • 00:29:43
    test B treaty the Soviet Union refused
  • 00:29:46
    to allow on-site inspectors at its
  • 00:29:48
    nuclear
  • 00:29:50
    facilities as a result the US opted to
  • 00:29:53
    monitor the Soviets by developing an
  • 00:29:55
    orbital satellite system capable of
  • 00:29:58
    detecting gamma ray bursts produced by
  • 00:30:00
    nuclear
  • 00:30:02
    [Music]
  • 00:30:04
    explosions because the satellites
  • 00:30:06
    detectors looked up as well as down
  • 00:30:09
    scientists decided to use them to see if
  • 00:30:11
    supern noi produced gamma rays when they
  • 00:30:17
    exploded between 1969 and
  • 00:30:20
    1972 they detected evidence of 16 short
  • 00:30:23
    gamma ray bursts scattered across the
  • 00:30:26
    sky there was just one problem none of
  • 00:30:29
    the bursts correlated with any of the
  • 00:30:31
    known Supernova
  • 00:30:34
    events and the Mystery deepened over the
  • 00:30:38
    next two decades astronomers detected an
  • 00:30:40
    average of one gamma ray burst a day but
  • 00:30:44
    each burst happened so quickly that it
  • 00:30:46
    was over before astronomers could get a
  • 00:30:48
    telescope aimed at
  • 00:30:51
    it of other gamma ray bursts have been
  • 00:30:54
    similarly documented all just as
  • 00:30:56
    powerful and far away
  • 00:31:00
    as for what it all means the discovery
  • 00:31:02
    of gamma ray bursts have once again
  • 00:31:04
    shown us that hidden out there behind
  • 00:31:07
    the veil of the Earth's atmosphere are
  • 00:31:10
    objects that are not only strange and
  • 00:31:12
    hard to Fathom black holes pulsars
  • 00:31:16
    quazars but they're lethal
  • 00:31:18
    too gamma ray bursts are now considered
  • 00:31:21
    a possible cause of past Extinction
  • 00:31:23
    events on Earth
  • 00:31:28
    the scientist Sir Arthur Edington once
  • 00:31:31
    noted not only is the universe Stranger
  • 00:31:33
    than we imagin it is Stranger than we
  • 00:31:36
    can imagine he could have been talking
  • 00:31:38
    about gamma ray bursts the expanding
  • 00:31:40
    universe or the theory of general
  • 00:31:43
    relativity it also happens to be a
  • 00:31:45
    perfect description of our next
  • 00:31:49
    [Music]
  • 00:31:56
    Discovery once it would have been a
  • 00:31:58
    impossible for astronomers to imagine
  • 00:32:00
    discovering other solar systems with
  • 00:32:02
    planets like our
  • 00:32:04
    own but today astronomers can imagine
  • 00:32:07
    thanks to powerful space and groundbased
  • 00:32:09
    telescopes like the one here at the Lick
  • 00:32:11
    Observatory in Mount Hamilton California
  • 00:32:14
    where Jeff Marcy is hunting for new
  • 00:32:16
    planets how do you go about finding a
  • 00:32:19
    planet around a star well it's very easy
  • 00:32:21
    we watch the star to see if it wobbles
  • 00:32:24
    in response to the planet yanking on it
  • 00:32:26
    gravitationally very easy EAS very easy
  • 00:32:30
    oh you just need one of these that's
  • 00:32:32
    right this is the 3M Lick Observatory
  • 00:32:38
    telescope by definition planets don't
  • 00:32:41
    produce their own energy they shine of
  • 00:32:42
    course by reflected light but planets
  • 00:32:44
    are about a billionth as bright as their
  • 00:32:47
    host star so you can't really see them
  • 00:32:49
    even with the Hubble you need a trick
  • 00:32:51
    and that's what we use with this
  • 00:32:52
    telescope a trick the Doppler effect is
  • 00:32:55
    our trick we measure the wobble of a
  • 00:32:57
    star
  • 00:32:58
    by the changing light waves that come
  • 00:33:00
    from the Star as the star
  • 00:33:03
    wobbles the search for extraterrestrial
  • 00:33:05
    planetary systems gain momentum in the
  • 00:33:08
    early 1990s when a Polish astronomer
  • 00:33:10
    made a surprising discovery there's a
  • 00:33:14
    wonderful Discovery by Alex volchan of a
  • 00:33:17
    system of three planets orbiting a
  • 00:33:19
    pulsar and the way he found him was
  • 00:33:21
    quite exciting he watches the pulses
  • 00:33:24
    coming from the pulsar and the arrival
  • 00:33:26
    of those pulses changes as the Pulsar
  • 00:33:28
    approaches and recedes us these are
  • 00:33:31
    hideous stars pulsars have ultraviolet
  • 00:33:34
    X-rays and gamma rays coming off them
  • 00:33:36
    they're the bizarre end products of a
  • 00:33:39
    supernova explosion and despite that
  • 00:33:41
    bizarre environment here we have
  • 00:33:43
    earth-sized planets going around if
  • 00:33:45
    there are earth-sized planets around
  • 00:33:47
    pulsars you can bet there are
  • 00:33:48
    earth-sized planets around other stars
  • 00:33:51
    there are earth-sized planets around
  • 00:33:52
    Paul stars earth-sized and even
  • 00:33:54
    moon-sized among the three he detected
  • 00:33:56
    those detected them by this wobble of
  • 00:33:59
    the Pulsar well that's just the coolest
  • 00:34:01
    thing in the world it's unbelievable
  • 00:34:03
    since Von's Discovery Marcy and other
  • 00:34:05
    astronomers have found more than 130
  • 00:34:08
    extra solar planets we thought we would
  • 00:34:11
    never find even one planet and we have
  • 00:34:13
    found the world's only triple Planet
  • 00:34:15
    system and quadruple Planet system with
  • 00:34:17
    this telescope oh my so these are these
  • 00:34:19
    are Big Planets though these are planets
  • 00:34:22
    the size of our Jupiter Saturn and the
  • 00:34:24
    smallest are Neptune sized yeah little
  • 00:34:27
    Neptune so it's quite exciting we're
  • 00:34:29
    finding planets of Jupiter size but even
  • 00:34:31
    those a few times bigger than the earth
  • 00:34:34
    while no earthlike planets have yet been
  • 00:34:36
    found the search continues how do you
  • 00:34:39
    pick a
  • 00:34:41
    star as a candidate we indeed try to
  • 00:34:44
    choose stars that are more or less like
  • 00:34:46
    our son some more massive some less
  • 00:34:49
    massive but sort of middle-aged or older
  • 00:34:51
    so they've settle
  • 00:34:53
    down what you want from an earthlike
  • 00:34:56
    planet to make it habitable is the
  • 00:34:58
    temperature has to be just right not so
  • 00:35:00
    cold that the water's locked up into ice
  • 00:35:02
    not so hot that the water's evaporated
  • 00:35:05
    into steam but a planet just the right
  • 00:35:07
    distance from its star so that the
  • 00:35:09
    temperature is just right for liquid
  • 00:35:12
    water over billions of years to let
  • 00:35:14
    darwinian Evolution do its thing sounds
  • 00:35:16
    like Goldilocks and her porridge that's
  • 00:35:18
    right you don't want it to be too hot or
  • 00:35:20
    too cold but suppose you had a telescope
  • 00:35:23
    a gizmo a device sensitive enough to
  • 00:35:26
    find an earth plan mhm would you point
  • 00:35:29
    it at some of the Stars you've already
  • 00:35:31
    identified as having plets absolutely
  • 00:35:33
    the Jupiters and the Saturns we're
  • 00:35:35
    finding are the the signposts the
  • 00:35:37
    benchmarks of systems that might Harbor
  • 00:35:39
    Earths and especially if there's a
  • 00:35:41
    Jupiter far enough from the host star
  • 00:35:44
    that leaves room for an earth in the
  • 00:35:46
    habitable zone to be orbiting that
  • 00:35:50
    star what made you go looking for
  • 00:35:53
    planets on other stars well I remember
  • 00:35:56
    when I was a young kid did I thought to
  • 00:35:58
    myself I wonder if there are other
  • 00:36:00
    Earths out there and if so are any of
  • 00:36:02
    them habitable and then is there life on
  • 00:36:04
    those planets and in particular
  • 00:36:06
    intelligent life we humans I think in
  • 00:36:08
    general would love to know are we alone
  • 00:36:10
    in the universe are there other planets
  • 00:36:12
    like Earth habitable planets are there
  • 00:36:14
    other creatures out there that think and
  • 00:36:16
    dream and indeed are searching for us in
  • 00:36:19
    the end I think we humans are trying to
  • 00:36:21
    find Our Roots out there chemically and
  • 00:36:24
    biologically Among the Stars
  • 00:36:28
    [Music]
  • 00:36:33
    as the universe expanded following the
  • 00:36:35
    Big Bang logic dictated that the
  • 00:36:37
    gravitational attraction of all matter
  • 00:36:39
    should pull at that expanding material
  • 00:36:41
    and cause the expansion to slow but how
  • 00:36:44
    much was the universe slowing down in
  • 00:36:46
    the 1990s the Hubble Space Telescope
  • 00:36:49
    made it possible for teams of scientists
  • 00:36:51
    to answer the question by studying the
  • 00:36:53
    brightness of light from a special type
  • 00:36:55
    of exploding star called a type 1 a
  • 00:36:59
    supernova I paid a visit to the Lawrence
  • 00:37:02
    Berkeley National Laboratory in San
  • 00:37:04
    Francisco and met with astrophysicist
  • 00:37:06
    Saul Pearl who headed up the Supernova
  • 00:37:09
    cosmology
  • 00:37:11
    project so what did you find out so we
  • 00:37:15
    started to make a measurement to try to
  • 00:37:17
    find out how much the universe in its
  • 00:37:20
    expansion is slowing down when we first
  • 00:37:23
    saw the data you you say well that's
  • 00:37:25
    that's kind of funny it kind of looks as
  • 00:37:26
    if the universe isn't isn't slowing down
  • 00:37:28
    um but youum well but you know we're
  • 00:37:30
    also right in the midst of doing all
  • 00:37:31
    these checks and and calibrations and
  • 00:37:33
    confirmations and I'm sure once we um
  • 00:37:35
    get all the numbers you know checked out
  • 00:37:37
    and figured out that the effect will go
  • 00:37:38
    away change of sign somewhere that we
  • 00:37:40
    have to fix there's a minus sign yeah
  • 00:37:42
    right you know say is trivial that you
  • 00:37:44
    check each step of the of the process
  • 00:37:46
    and little by little um you get to the
  • 00:37:47
    point where you start realizing you know
  • 00:37:49
    this effect isn't going away this is the
  • 00:37:51
    right answer it really looks like the
  • 00:37:52
    universe is actually speeding up so why
  • 00:37:54
    is this so important this acceleration
  • 00:37:57
    of the universe doesn't fit at all we
  • 00:38:01
    understand pretty well what all the
  • 00:38:02
    forces are in the universe and what all
  • 00:38:04
    the objects are in the universe and this
  • 00:38:06
    is one of the first times that we've
  • 00:38:08
    come across something that we wouldn't
  • 00:38:09
    have predicted now we're having the fun
  • 00:38:10
    of trying to figure out what does this
  • 00:38:12
    all mean and if you come with me I'll
  • 00:38:13
    show you a little bit about what we're
  • 00:38:14
    doing about
  • 00:38:16
    it why is it accelerating well that's
  • 00:38:19
    the question that has us all dying to
  • 00:38:22
    know the answer and I mean one way to
  • 00:38:24
    think about it is that if you have a
  • 00:38:26
    energy of this sort that would pervade
  • 00:38:29
    all space it can actually speed up the
  • 00:38:31
    universe when gravity is trying to slow
  • 00:38:33
    it down and we're calling that dark
  • 00:38:35
    energy just to reflect the fact that we
  • 00:38:36
    don't know what it is it's a mystery
  • 00:38:39
    it's completely mysterious bizarre we
  • 00:38:41
    have no idea what it is we want to do
  • 00:38:43
    studies to figure out what could dark
  • 00:38:44
    energy be like what we want to do now is
  • 00:38:46
    get data that will help pull apart the
  • 00:38:49
    different answers so where you going to
  • 00:38:51
    get that data the big picture goal that
  • 00:38:54
    we're after is a project that you see
  • 00:38:56
    around you here um which is a satellite
  • 00:38:59
    project the uh design that we have here
  • 00:39:01
    we've called Snap which is short for
  • 00:39:03
    Supernova acceleration probe this would
  • 00:39:06
    be a new Space Telescope with a very
  • 00:39:09
    very big field of view so instead of
  • 00:39:11
    looking through a little Keyhole at the
  • 00:39:12
    universe you'd be looking through a good
  • 00:39:13
    picture window at the
  • 00:39:16
    universe so let me show you what we're
  • 00:39:18
    working on that we think might help us
  • 00:39:21
    get out why the universe is accelerating
  • 00:39:23
    what this dark energy really
  • 00:39:26
    is here we have snap that we're hoping
  • 00:39:29
    to be able to launch not to distant
  • 00:39:32
    future this one goes out to a uh
  • 00:39:36
    location out past the
  • 00:39:37
    Moon from that bage point you can
  • 00:39:40
    measure the expansion history with such
  • 00:39:42
    detail that we could actually see the
  • 00:39:44
    little changes when it goes from
  • 00:39:46
    deceleration to acceleration back when
  • 00:39:48
    the universe was really dense and and
  • 00:39:51
    and uh close together gravity was more
  • 00:39:53
    important and it slowed the expansion
  • 00:39:54
    down as it kept expanding though even
  • 00:39:57
    slower and slower it lost out and
  • 00:40:00
    gradually became less important than the
  • 00:40:01
    dark energy which took over and started
  • 00:40:03
    to accelerate the expansion and we're
  • 00:40:05
    after exactly how that change over
  • 00:40:07
    occurred and that will tell us about
  • 00:40:10
    what different possible theories could
  • 00:40:12
    be right to explain the dark energy
  • 00:40:13
    always expanding but slowly then
  • 00:40:16
    speeding up exactly that's where we are
  • 00:40:18
    now exactly so it's it's this issue of
  • 00:40:20
    did did it slow down and then suddenly
  • 00:40:22
    spurred or did it slow down and you know
  • 00:40:24
    and come to a wobble and then take off
  • 00:40:27
    um you know what was that that
  • 00:40:29
    transition
  • 00:40:33
    like just like the ancient astronomers
  • 00:40:36
    modern scientists have discovered
  • 00:40:39
    something about the cosmos that we
  • 00:40:41
    cannot yet explain it will be up to
  • 00:40:43
    observers and theorists to figure out
  • 00:40:45
    what's going on in our expanding
  • 00:40:47
    Universe for this they'll need new ideas
  • 00:40:50
    and better instruments now whether this
  • 00:40:53
    mystery is solved soon or far in the
  • 00:40:56
    future you can be certain of one thing
  • 00:40:58
    we will keep watching the skies to
  • 00:41:01
    understand our place in the cosmos we
  • 00:41:03
    will continue to
  • 00:41:06
    explore understand and discover
  • 00:41:15
    [Music]
  • 00:41:21
    [Music]
  • 00:41:28
    [Music]
Tags
  • Astronomy
  • Space
  • Discoveries
  • Copernicus
  • Hubble
  • Galileo
  • Exoplanets
  • Dark Energy
  • Kepler
  • Universe