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Celebrating Stephen Hawking’s Most Famous Discoveries

Celebrating Stephen Hawking’s Most Famous Discoveries

[♪ INTRO] Last week, the world lost one of the few science
celebrities of the modern era: Stephen Hawking. He was a man who gave lectures to sold-out auditoriums, and he has the honor of being the only person
to ever play himself on an episode of Star Trek. And Hawking’s fame was not unfounded. He published papers for over 50 years! He worked on a lot of problems in modern physics, from proposing what could have
existed before the Big Bang, to hunting for an elusive theory of everything. But his most notable work was on black holes. In honor of one of the greatest legacies in
cosmology, we wanted to celebrate and unpack
some of his most famous findings. First, in the 1960s, theoretical astrophysicists finally settled on black holes being a ‘real’ thing. At the time, they believed that once
a particle passed an event horizon, what we call the ‘surface’ of a black hole,
it could never come back. These things were a one-way trip to ultimate
obliteration. But in the 1970s, a handful of physicists
started to question that, including Hawking. After building on previous ideas and doing lots of
math, he eventually generated a startling conclusion: Black holes are not truly black. Surprise! Just when you think you know
what’s going on in the universe, Stephen Hawking comes along! It turns out black holes emit a faint but steady
stream of particles now called Hawking radiation. And by proposing it, Hawking set the stage
for some of the most important work currently happening in physics. This radiation happens because quantum mechanics
requires an intrinsic uncertainty to the universe. The short explanation is that,
even in so-called ‘empty’ space, there are actually pairs of particles constantly popping into and out
of existence over very small timespans. We call them virtual particles. As long as these particles collide and annihilate
one another, the laws of physics don’t care. The energy is returned to space super duper
quickly, so there’s no net change in the universe. Now, Hawking realized that if one of those pairs happens to form at the event horizon of a black hole, the object’s extreme gravity could force them apart. That would give them enough energy
to become real particles. Then, one could fall into the event horizon,
while the other could fly away. And those escaping particles are what we’d
detect as Hawking radiation. As they escaped, these particles would also
carry away the energy the black hole gave them. And as a result, the hole would lose a tiny
bit of mass. In other words, Hawking radiation causes black
holes to evaporate. We haven’t actually detected this radiation yet, mostly because our technology
just isn’t good enough. But it is required to work out the math, so
we’re pretty confident it’s real. As a bonus, this phenomenon also sits at a
critical juncture in astrophysics. Because it involves both
huge black holes and tiny particles, it connects the laws of general relativity
and quantum physics. These are the laws that respectively govern
the very large and the very small. These principles don’t tend to play well together, and scientists have been trying
to unite them for a while. And if they can do that,
they could create a theory of everything, a single model that could explain
how the whole universe works. So by proposing this radiation’s existence,
Stephen Hawking laid the foundation for the progress that’s been made
on that theory in recent years. Of course, black hole evaporation also presents
us with a bit of a physics problem, which we’ve mentioned on SciShow Space before. Separately, both general relativity and quantum
mechanics predict that the present time period preserves information about the past. And that makes sense. After all, we usually think about causes happening
before effects. But no matter what sorts of particles fall
into a black hole, the outgoing Hawking radiation is always the same. The black hole seems to lack all information
of what you threw in there, which doesn’t make sense. This is called the Black Hole Information
Paradox. And Hawking and other physicists have attempted
to resolve it over the decades. Back in the 1990s, Hawking and fellow physicist
friend Kip Thorne even made a wager about the answer,
which was pretty common for Hawking. They bet Thorne’s colleague John Preskill
that the math would eventually prove that the information that falls into
a black hole is indeed lost forever. Unfortunately, despite lots of work, there’s
no definitive answer yet. Hawking did concede in 2004, but many physicists
argue the puzzle isn’t really solved. Still, this doesn’t make the discovery of
Hawking radiation any less significant, it just means there’s always more to know. Another one of Hawking’s major ideas,
which he proposed in 1971, was the existence of black holes that
did not form from collapsing stars. Instead, he suggested that they formed
within the very first second of the universe, thanks to the density of energy fluctuating
as space expanded and cooled. Because they didn’t come from stars,
these so-called primordial black holes would supposedly have
a wide range of possible masses. They could be anywhere from
one ten-thousandth of a gram, the smallest they could possibly be according to physics as we know it, to thousands of times the mass of the Sun. Hawking said the really tiny ones
would have evaporated a long time ago, but those with a mass around 10 trillion
kilograms would just be ending their lives now. As the mass of these black holes approaches
zero, they should experience runaway evaporation. That would create a massive burst of radiation equivalent to millions of
one-megaton hydrogen bombs. And those explosions could, hypothetically, be detected by instruments
like NASA’s Fermi Telescope. Hawking suggested that
several primordial black holes could even lie hiding in the Milky Way’s halo. And other astrophysicists have
identified them as a possible candidate for the mysterious stuff
we currently call dark matter. So it could turn out that Hawking was responsible
for proposing what dark matter really is. But only time will tell. As we keep building off Hawking’s work, there’s a chance he could still get his name
somewhere else in the astrophysics textbooks. But no matter if that happens or not, it’s
clear that the thoughts Stephen Hawking had and the work he contributed will resonate
with people, and not just scientists, for generations to come. Besides being a brilliant physicist, he was
also a powerful advocate for science, and a lot more people are in love with the universe
because of what he did. So thanks, Stephen Hawking. Thanks to you, we’ll remember to look up
at the stars and not down at our feet. And thank you, for watching. If you’re looking for a tangible way to
celebrate your love of the universe, please check out SciShowFinds.com. This is a little corner store of the internet that
Hank and the team set up so that we could share physical things that remind us how much
we love science and care about the universe. One of the items that I picked out is the PocketLab which lets you gather data and
do experiments wherever you are. And I just got my bee heart pin, so I’m
hoping to run into people out in the world with the same pin and we can talk about mason
bees, and pollination, and colony collapse! Another of my favorite finds too, are the
Climb Mars socks with Olympus Mons on them. My plan is to wear them when I’m not
feeling as adventurous as I want to, so if I do forget and start looking down at my feet, they’ll remind me to look up at the stars
and remember Stephen Hawking. [♪ OUTRO]

100 thoughts on “Celebrating Stephen Hawking’s Most Famous Discoveries

  1. And all of this will be disproven in the not so distant future. Besides it is well known long before modern science that everything emits some level of energy through radiation. Pretty much everything Hawking took credit for is plagiarized and the elaborations are wrong or at the very least misguided.

  2. Apparently, you got Hawking radiation wrong;
    although, I guess, it's k with the simple, not quite correct version, usually…
    Kinda disappointed, that you, went with it though…
    F.Y.I.: PBS Space Time, has the proper explanation, in a recent video.

  3. A truly significant human being, he had quite an impact on me, especially with regards to what the lady said in the end of the video. Thank you Mr Hawking, your name may live forever and sound in the echos of the generations to come.

  4. Then, of course, is his incredible civic involvement fighting the Vietnam War, South African and Israeli Apartheid by endorsing the non-violent, Palestinian civil society call for the world to boycott, sanction and divest from Apartheid Israel until it complies with international law. I'm not trolling. Steven was a man who recognized the horror of Apartheid Israel. He would not want this part of his legacy glossed over.

  5. I worship Steven Hawkings every day. I am really sad that he died 🙁 I am going to sacrifice 1000 Souls each day to hopefully bring Steven Hawkings back to life so he coud lead humanity to glory and victory against the xenos the mutants and the heretics!

  6. I only need one answer if his disease ALS according to the science can let the people live for 3 years which power took him to this age.

  7. Nice guy .But it's a pity all his work is all false and based on theory which he failed to provide proof.pity he went as his predecessors should have went on electric.as his wheelchair was better equipped for this and he just couldn't see it.PITY.

  8. Stephen Hawking isn't resting in peace. He will continue to influence our future with his ideas and theories, as did Newton, Einstein, and many other great scientists!

  9. To me his best work was A Brief History of Time, bringing all this stuff to the lay person before youtube channels like this. Thanks Stephan Hawking. RIP.

  10. Hawking was ONLY known for Space related Discoveries…so in other words, he did nothing for the Human Race as we were in his Life Time… Thanks for nothing… On a Side note, it's possible he was Body Snatched to become a Figure Head.

  11. Imagine if a republican ditched his wife for his nurse. Yup! It would define and summarize his accomplishments.

  12. They only celebrate if you're dead. No one cares about your discoveries if you're alive. They only see your mistakes when you're alive and they see your good works after you die.

  13. He was a athiast, but I pray he accepted jesus christ b4 he passed. The universe is un explained but god says we will understand it better by and by. The greatest scientist is our lord & father.

  14. Bad tribute 🙁 selling merch at the end is incredibly distasteful, it's like the coffin company advertising at a funeral :/

  15. The biggest liar ever lived. He was just a masonic puppet, just like you. Everything on you're channel is a lie.

  16. Hawking biggest blunder-He said there is no GOD.That everything just happened on its own.He is burning in hell without JESUS.For such a smart dude he sure was a FOOL.He was an atheist and lost forever.I'm sorry but he will never see those stars from the darkness of hell.
    DON'T make the same mistake Accept Jesus today .He LOVES YOU and wants to save you.Jesus died on the cross for our sins-EASTER!!!!!!!!!!!!

  17. One question I've never understood about Hawking radiation. Why don't the particles and anti-particles fall in with equal frequencies? Meaning that there is no net change in the black holes size. Anyone know the answer or a vid that answers this?

  18. Thank you so much for these words and explanation. I'm so grateful for Hawking's contribution and inspiration. He was a scientist of a kind. I met cosmology through his books and lectures almost a decade ago, and today this area is the most fascinating topic of science for me. I love the content of this channel. Please keep doing this amazing job/hobby for us, science lovers. You guys are increasing the entropy of the universe. ❤🌌

  19. I mean, black holes are just heavily dense stars in concept. I assumed this was obvious until everyone made a big deal about it. It's no less lost than information thrown into the sun; the entropy of the matter representing it would be escalated. They're black to observable wavelengths of light because it's drawn in at a specific curvature rate based on its gravitational pull. If their density were to drop spontaneously to the point where it can't draw in light; then all of that energy would be released, and instead they would be the brightest things in the universe.
    The idea of information being lost is flawed when you account for the passage of time making its vessel infinitely more complex all the time. There are dimensions at work in black holes that our brains can't comprehend, I accept that, because relatively it wouldn't make sense for a 2d creation to grasp its 3d structure, in my opinion.

  20. I love that you guys make a point of acknowledging his Star Trek appearance! By far my favorite little trivia bit about him, and his smile in that scene is just perfect!!!

  21. The measure of a man is in how he is remembered. He might have been brilliant in his chosen field…but he was an avowed athiest…cheated on his wife…and by news reports shortly after his death…treated both of his wives and children very badly over the course of decades. When we immortalize a man…we need to see through a clear lens…looking at both his successes and his failures. He apparently was a success on the world stage…but as a human being…was sadly…quite a failure.

  22. 😀😀😀😀😀😃😃😃😃😃😃😃😃😃😃😃That creepy smlie when you talk about his death right at the beginning…….

  23. Hank Green shoulda hosted this episode.
    And why isn't anyone grieving? Stephen Hawking JUST DIED.
    I'm very disappointed.

  24. In my opinion he was a inspiration to keep going towards dreams, goals etc. no matter what. Brilliant guy.

  25. 5:51 Which is terrible, he will then be responsible for people stumbling over things. Thank god he is dead, so he can't be sued.

  26. Professor Stephen Hawking 1942-2018

    May you be among the stars every night with Einstein, Newton, and all the others.

  27. Guys, at the end of the universe, all there will be is black holes, and when they all die, the only thing left in the universe will be Hawking radiation! He will be the last thing in the universe!

  28. Love the positivity, and upbeat style. About time we head towards celebrations of life instead of sad funerals. Also, I honestly don't understand the people complaining about the presenter… I went back and tried to find things wrong with her, but I couldn't find anything.

  29. I'm glad Caitlin didn't lose her enthusiasm in this tribute as Stephen Hawking never wanted to be mourned but to be remembered rather for his works and contributions in astrophysics.

  30. ohh I miss the man (Hawkings). Life just feels surreal when I catch myself wondering what he's up to and then remember that he's not hanging around forever like I was formerly expecting

  31. As science detected this black hole evaporation? Or is that just a theory too? Have we ever seen a black hole there and then not there ?

  32. What is the meeting point of the Very Big (that follows one type of physics) and the Very Small (which follows another type)?

  33. Ok, I've about gotten my mind around dark matter/energy, now you want to throw "virtual particles " at me ,that jump into existence and physics don't care??!!?? Where did they and why did they, pop into our universe????

  34. I love it when scientists come up with more theories that they can't prove yet…like a nerd that says he has a girlfriend, but won't present her to any of his friends.😐 RIP Hawkins

  35. Someday, when we have the technology, I think we should put his body in a space coffin (like the one Spock was put in during the original movie franchise) and set him on course for Saggitarius A*, where he literally will become one with the heart of the galaxy, in the object he insisted existed, and was right.

  36. Theorizing about things that we can’t see or touch. Physically unproven. Science is a religion. An interesting one, I’ll admit.

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