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0:00
So, I'm Neil deGrasse Tyson, your personal astrophysicist, and I was invited in with these fun props like inflated planets to answer questions, your questions, about the universe.
0:11
So bring it on, questions from the internet.
0:16
I got one here from Cain Jackson: how many stars are born per year, how many die?
0:27
Well, it's about a hundred a year in our galaxy.
0:27
We've had like a stable amount for the last several billion years.
0:27
And where you calculate that is, we have about a hundred billion stars in the galaxies and universe is ten or so billion years old, about a hundred a year, maybe ten and a hundred a year.
0:27
So you got it.
0:27
Next up, from Maccabees: dude, I love questions that begin with "dude."
0:27
There's literally a quark called strangeness because nobody freaking knows what the hell it's doing.
0:50
But what is going on, damn, I hate physics, that's not a question.
1:00
We have quarks named up, down, bottom, top, strange, and charmed.
0:57
We don't see them directly, we can't tell you what, we can't show you a photo of them.
1:04
So they're just placeholder words for them, so just like, just get used to that.
1:08
All of quantum physics transcends our personal life experience, so to describe it, we have to sort of invent words.
1:18
One of them is just strange.
1:20
That doesn't mean we can't describe it and know what it, how it behaves, in and of itself, and with other quarks.
1:27
So don't put too much meaning in the word itself, it's the idea that matters.
1:32
Next, Jordan: Is it just a coincidence the two major hurricanes, a spreading wildfire, and now an 8.4 magnitude earthquake followed the solar eclipse?
1:43
Yes.
1:43
By the way, there's solar eclipses every 18 months or so.
1:43
Find something to happen there and you want to blame it on the eclipse, okay, go ahead.
1:43
People did that for millennia.
2:29
No, no.
2:35
What do we have here, a dagger, a pm.
2:35
If dark energy makes the universe expand, it makes it might make more or new space, can we use that space to make dark energy?
2:35
Um, I, I don't know.
2:35
By the way, dark energy is not so much making us expand, we were already expanding, it is making the expanding universe accelerate, that's what's going on.
2:35
Evidence shows that dark energy is not being created in the expansion of the universe, so I think the answer to this is no.
2:35
But if one day we could control dark energy in a lab, maybe we might discover interesting properties in its relationship to dark matter, I don't know, to be determined.
2:41
Watch this space.
2:47
Next up on Twitter, Charles William Johnson: If the Higgs boson, et cetera, forms an essential part of reality, which it does, why can't it be found in our front room or all around us?
2:57
There's certain parts of our fundamental reality that you only gain access to under certain conditions of pressure and temperature and energy.
3:05
You don't experience a proton in your life, but it's a fundamental part of nuclei that make up the atoms that comprise your body.
3:13
So just because you don't see it, feel it, touch it, taste it, or smell it does not mean it does not exist.
3:17
And part of the entire purpose of why we have science at all, in particular the methods and tools of science, is to decode that which is true about nature that otherwise transcends your sensory perceptions.
3:32
That is what science is.
3:32
You wouldn't need the tools if our brain sensory system accurately decoded the world around us, but it doesn't, and that's why science tries to find any way it can to remove your brain, ie, your nose, mouth, touch, from the operation.
4:53
And the more we can successfully do it, the less bias shows up in the result.
4:53
Just get the human out of it.
4:53
So, yeah, reality is not what you perceive, it's what the methods and tools of science reveal.
4:53
Next up, Wow, Across the Universe is a musical.
4:53
I don't know, is it?
4:53
I love musicals.
4:53
If it is, I'm embarrassed that I haven't heard of it, but it ought to be, seems to me the universe would be really good.
4:53
Next, Marilyn Baker: What is a quantum particle?
4:53
Is it like say a quark where's an electron?
4:53
What quantum physics is the study of everything that matters on that scale, electrons, quarks, neutrons, nuclei themselves, atoms themselves, molecules themselves.
4:53
There is no understanding of what they do without quantum physics.
4:53
That's how small particles roll in this world.
4:53
Hope that answers your question.
4:53
Within these hundreds of newly confirmed exoplanets, how many are possibly habitable by the actual scientific method we have?
4:53
So you look for exoplanets, planets orbiting other stars.
4:53
Some fraction of them are in the Goldilocks zone, not too close, if it had liquid water would evaporate, not too far, they haven't had liquid water would freeze.
4:53
Now you can calculate what that is for any star, and so there's a subset of all the thousands of exoplanets, there's a few hundred that orbit in the Goldilocks zone.
5:22
Life as we know it could thrive there.
5:25
Haven't found life, still looking for life, but it could thrive there.
5:30
By the way, there are other sources of heat, sources of heat from tides that are created from the main planet, Jupiter for example, onto its moons.
5:43
So there are moons of Jupiter.
5:43
Jupiter's way outside the Goldilocks zone.
5:43
The moons of Jupiter are kept warm by this sort of gravitational massaging.
5:43
It's called tidal heating, T I D A L tidal heating.
5:43
So you might have life as we know it on the moons of planets that have tidally heated those moons.
5:43
So that opens the net forecast a much wider net in a search for life in the universe.
5:43
I'm not sure if anyone has asked or answered, but I'm curious where was Neil Tyson for the solar eclipse?
5:43
Hopefully it was a clear sky.
5:43
Thank you for those warm wishes.
5:43
It was a state secret where I was right up until the eclipse.
5:43
I was at Deadwood Lookout, 7,200 feet up in the mountains of Idaho, checking out the total solar.
6:26
Is the universe expanding into a space bigger than the universe itself?
6:35
Is there a clear limit to the expansion?
6:37
So yeah, we're expanding, but if that's what we define all of space to be, then there's higher dimensions into which this is happening.
6:46
In principle, you can go outside of our universe and look down on it or up to it, but then you're in another dimension, so we don't have access to that dimension, so we're stuck.
6:58
We're given three spatial, one time dimension, get over time.
7:00
For just a couple more, whatever.
7:02
Donnie Yell: If aliens exist, how do I know I'm not one?
7:08
Well, if you visited another planet with life, you'd be an alien to them.
7:11
Clearly, you're probably not an alien because you share all the same organs in the same place with the same biochemistry and highly common DNA with the person sitting across from you and everyone else walking this earth.
7:26
You have DNA in common with yeast cells, with an apple, with oak trees.
7:31
So that's some of the best evidence we know that you yourself are not an alien.
7:38
Jacob Warren: You all believe in quantum mechanics or a theory of relativity?
7:43
Which one is better?
7:43
You don't have that choice.
7:46
They each exist and work and make predictions that are verified.
7:50
They're both kind of crazy, but they apply to reality.
7:54
Now it turns out we already know the limits of relativity.
7:57
It can't describe the center of a black hole, so we know relativity will have to be extended or modified in those extremes to understand that quantum physics, quantum mechanics, it works every single place we have ever applied it, every single place.
8:12
So in that regard, it is the most successful theory of the universe that has ever been put forth.
8:16
It could be possible that in the future quantum physics will subsume relativity entirely to get you to those singularities, the center of the black hole and the beginning of the universe.
8:28
But right now, they both work and we're completely happy with them.
8:31
Last one, Naphthalene Twitter: So the theory of relativity, the prediction of the effects gravitational fields in space and peace.
8:54
I think the rise of science has promoted greater peace and prosperity in the world.
8:54
Certainly prosperity, and often where there's prosperity, there's less of a need to take your neighbor's stuff.
8:54
If you look at the era of science and look at the kinds of wars people fought and what fraction of people would die in a war of a culture, in spite of even these aberrations such as the first and second world war, a much smaller fraction of all humans died in those wars than who died in tribal wars.
8:54
If you go back thousands of years, you could lose a third of your men fighting in a battle just to gain access to a property that does not happen in organized war.
9:23
No war is good, of course, but it may be that science as a path to prosperity and health will remove many of the reasons why we ever had war in the first place.
9:37
So a theory of relativity has another branch, physics, science in general, peace, yeah, peace, yes.
9:44
So very impressed with the cosmic curiosity out there, keep them coming, and as always, keep looking up, guys.
10:00
You know about this, especially a thermometer, it's a closed system in this air in here, room temperature is generally cooler than your body temperature.
9:55
This is why we have to eat continuously as warm-blooded creatures to maintain this temperature difference.
10:10
We're basically 100 degree organisms, right?
10:12
Air is 70 degrees, so if I warm this air then cool.