What The Physics? Q&A

  • By Greg Kestin
  • Posted 02.14.18
  • NOVA

"What The Physics?!" host Greg Kestin answers questions from you, our viewers.

Running Time: 07:36


What The Physics?! - Q&A

Published February 14, 2018

Greg Kestin: One of my favorite things about making these videos are your awesome questions and comments. So today what I'm going to do is something completely different and I'm just going to directly answer the questions that you've sent me over Facebook and Twitter and YouTube.

So the first question is from BHole Nath, who asks: "What happens if a black hole collides with another black hole?" Well, if you have two black holes in space and they're coming at each other, they'll probably miss. But they're attracted to each other, so they start dancing, they start spiraling in toward each other, and then, eventually they go *whoosh* and they suck up into one huge back hole. What's even cooler is that when they're going around each other, they give off gravitational waves. Like wave of gravity. This is true for any mass that's accelerating, like if you have your hand, which is made of mass, and you accelerate it, gravitational waves come off of it it. You can't detect them because they're very weak, but there are gravitational waves. And with black holes, you can actually detect those gravitational waves because they're super-huge. And in 2015 at LIGO, the Laser Interferometer Gravitational Wave Observatory, they actually detected gravitational waves from two black holes colliding.

In our previous video about how to see quantum with the naked eye, iM4rtyx4 asks: "Is it possible that these streaks can be seen on photos?" So the answer is yes. In the video I talk about how if you look at a light and you squint, you can see streaks of light coming off the lamp or whatever you're looking at. And you can actually also see those in photos. So if you take your phone and you put, say, two credit cards in front of the camera and then take a picture, just like through a slit, you'll actually see two streaks of light coming off, you know, if it's a lamp you're taking a picture of, you see streaks of light coming off of it.

In the video "Can We Measure Consciousness?" Sjors de bruijn3 asks, "What if I take my barely conscious phone and use it to simulate what would be a conscious machine? Like what would be a conscious process? Would that be considered consciousness inside a non-conscious machine? Did I just create consciousness?" Well, sort of. So, in the video I describe how the Integrated Information theory of Consciousness, which is a consciousness theory that's growing in popularity, can calculate the amount of consciousness, say, in a computer, or in a thermostat, or in some circuitry, and hopefully could eventually calculate it in the brain. Your consciousness is so large -- so much consciousness -- it's kinda tough to calculate. So in that video, a phone is a little conscious. In order to make your phone more conscious, what you'd have to do is you'd have to make a bunch of connections that are more integrated. Like, for example, in your brain, every neuron is connected to, like, thousands of other neurons. It's very interconnected; you couldn't just pull out one neuron and the brain would be fine. And so if you somehow took the circuitry in the phone and made it so there were a lot of interconnections -- like every wire connected to, you know, 1,000 other wires and they all looped back on themselves so it could also be more self-aware. Then you'd be making it more conscious, but the software itself -- if you just run a particular software on your phone, you can't make it any more conscious.

Faiz Khan asks: "I would like to know about the conditions before the Big Bang." Alright, so Faiz, I also would really like to know this; lots of physics really want to know this too. The thing is that when the Big Bang happened, it created the universe, and that means that it created space and it created time. And with time came the concepts of before and after, past and future. And so to try to go before the Big Bang means to go before time...that is, before the concept of "before." So, it's hard to know what that means. Nobody knows. But if anybody out there has theories, send them my way.

Netron asks: "So, you do research? What's it like?" I've done lots of different kinds of research. I've done nuclear physics theory -- basically, take two gold nuclei, smash them together: what do you get? And what you get is something called quark-gluon plasma. It's a fluid made of the stuff that makes up nuclei. This fluid was at the beginning of the universe, and you can actually create it in these nuclear collisions. So that was really cool. I've done some fusion energy theory. I've done some gravitational wave physics. That's LIGO, the thing that detected the merger of two black holes. And my most recent research -- this is what I did my Ph.D on -- is theoretical particle physics. Basically, the smallest things in the universe -- specifically related to the Large Hadron Collider, which is smashing protons together and what you get out of those collisions. All of the research is similar in that it's a lot of being wrong and a little bit of being right. So, I sort of feel like at any point, I go down, like, 20 paths, and wrong-wrong-wrong-wrong-wrong, and then right. And you eventually can get to a correct answer, but you have to be wrong a lot.

Next question is from Tech News, who asks, "How come matter anti-quarks emit quarks at high energies, whereas protons and neutrons consist of three valence quarks?" So, what's going on is, basically, in a big collision, when you collide, say, two protons together like they do at the Large Hadron Collider, you basically get a mini explosion, where you get a bunch of new quarks just like popping out. But in a proton and a neutron, you sort of have bound together -- they're all like tied up -- three quarks. So any neutron or any proton is made of three quarks, which can't escape. So the question is: In one of these explosions, how come one anti-matter quark can just like emit a quark but inside a proton and a neutron you don't just get new quarks popping into existence? And the answer is that you actually do get new quarks popping into existence inside a proton and neutron. Anywhere in space, like at the smallest, most fundamental level, even like right here in this space, there's some quark and anti-quark -- like, here's an up-quark and an anti-up-quark -- basically the anti-matter of this quark -- coming into existence and then *pop* annihilating again. Or you could have, like, an electron and its anti-matter pair -- a positron -- come into existence and then *pop* annihilate again. So, basically, what's going on is that that's always happening, except when you collide two things together, these two things that come into existence, they have enough energy that they can just fly off and be detected. And that's what's happening inside the experiments at the Large Hadron Collider.

So the last question I want to answer is a question that I asked you and thousands of you told me the answer. So the question was: "If you took a laser beam and you shined it at one side of the moon and then flicked your wrist like this, you'd actually get a laser dot that moved across the moon faster than the speed of light. And how is that possible?" So, a lot of you gave this correct answer, which is really cool, which is basically that when you're holding the laser, it's like shooting photons. It's like shooting photons -- you go like this and it shoots photons there, shoots photons there, and each photon is moving at the speed of light. But they land in succession, right, so you have a photon lands on the moon, lands on the moon, lands on the moon, lands on the moon, lands on the moon. And if you follow where they're landing, it looks like it's a dot moving faster than the speed of light across the face of the moon. So, thank you for answering that question and if you have more questions about physics or reality or the universe, or where to get a cute little bunny like this, put it down in the comments. I'll answer it in the next Q&A.



Host, Producer
Greg Kestin
Samia Bouzid
Editorial Input from
Ari Daniel
Julia Cort
Additional Animation
Special thanks
Entire NOVA team
From the producers of PBS NOVA © WGBH Educational Foundation
Funding provided by FQXi

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