Is Gravity Actually a Force?

Added: 2026-06-03

[00:00:00]Since our universe appears to be a pancake shape, like planetary systems and galaxies, do galaxies orbit around some larger central structure, like an even more super mega blast massive black hole?

[00:00:14]Or are galaxy motions just more random or ununiformed? Um there you go.

[00:00:22]>> Universe is not pancake-shaped. So, next question.

[00:00:24]>> Well, there you have [laughter] it.

[00:00:27]It's waffle-shaped.

[00:00:29]>> No, but but to to the point, galaxy motions are mostly random.

[00:00:34]And >> Okay.

[00:00:35]>> What I What I mean by random is they're not coordinated in some big way, unless you're part of a galaxy cluster.

[00:00:40]>> Okay.

[00:00:42]>> then there's some some ballet of most movement. However, some structures in the universe are so large that the average speed of the galaxy moving among other galaxies in that cluster is insufficient for the galaxy to have made one complete loop through that cluster.

[00:01:04]>> Okay.

[00:01:05]>> So, that has significant consequences to what's going on there. It's called It's not virialized. A virialized cluster is a cluster that has a very mature shape where, like a beehive, all the galaxies are moving around. You step back, it has a spherical kind of envelope that contains them.

[00:01:24]>> Got you.

[00:01:24]>> But if it's kind of ratty >> Right.

[00:01:26]>> like that >> Yeah.

[00:01:27]>> it's not yet virialized. This comes from what's called the virial theorem, which talks about how energy can be transmitted, shared from objects with high energy to objects with lower energy, so that everybody has approximately the same energy at the end of the >> Oh, the process.

[00:01:44]>> Very cool. So, virialization is the sharing of that energy. So, it drops the energy of the high energy objects.

[00:01:49]>> Mhm.

[00:01:50]>> Um it could be thermal energy, it could just be orbital energy, and the lower energies come up. So, but that's a whole branch of physics when we talk about virialization of >> of uh of of galaxies.

[00:02:03]>> of of of of matter >> Oh, okay. Matter >> whatever situation.

[00:02:06]>> Okay.

[00:02:07]>> So, uh the ratty-looking galaxy clusters tend to not have been virialized.

[00:02:11]>> Got you.

[00:02:12]>> And so, yeah.

[00:02:13]>> All right. So, >> And by the way, we moving around the center of our galaxy takes about 200 200 million years.

[00:02:22]>> 200 million years.

[00:02:23]>> That's much smaller than the age of the galaxy, which is 13 billion.

[00:02:27]>> 13 billion years, right.

[00:02:28]>> Yeah, so so galaxy is in a mature shape.

[00:02:30]>> And we're in a spiral galaxy.

[00:02:32]>> Correct. Correct.

[00:02:33]>> That is very cool, man.

[00:02:34]>> Mhm.

[00:02:35]>> Uh good question. Uh this is MX self-destruct.

[00:02:38]>> Okay. Is that a Is that a >> That's what it says here.

[00:02:41]>> a thing here? Okay.

[00:02:41]>> MX self-destruct, I have no idea. But his name is Sheamus, and he says >> Sheamus?

[00:02:45]>> Yeah, he says, "Dr. Tyson, Lord nice.

[00:02:47]Sheamus here from Los Angeles.

[00:02:50]>> [gasps] >> We know that gravity is the result of the way space-time curves. So, wouldn't it be more likely that gravity is simply a side effect of this curvature rather than a force with a carrier particle like a strong, weak, or an electromagnetic force? If there is a carrier particle, why is it not just the Higgs boson, since that imparts mass, thus providing the curvature for the universe that we call gravity?

[00:03:18]>> Wow, is that Man, man, people man.

[00:03:22]>> People are doing some work, man.

[00:03:23]>> People man.

[00:03:24]>> People are doing some thinking.

[00:03:24]>> Man, so I I can answer 80% of that question.

[00:03:27]>> All right.

[00:03:28]>> It's an assumption >> Mhm.

[00:03:30]>> that gravitation as a force in the universe has a force-carrying particle.

[00:03:36]>> Right.

[00:03:37]>> And the assumption is that if you represented classical gravity even Einsteinian gravity with quantum physics, it would have to have a particle.

[00:03:49]>> So, we even named this hypothetical particle >> Okay. the graviton.

[00:03:52]>> The graviton.

[00:03:53]>> Right. Exactly. So, the hunt for the graviton is on.

[00:03:56]>> Right.

[00:03:56]>> All right. And so, the effect of the graviton and and mass and energy is to curve the fabric of space and time.

[00:04:05]Forcing you to move in certain ways that would not otherwise be the case if that were not occupying that space.

[00:04:11]>> Right.

[00:04:12]>> John Archibald Wheeler, a great physicist of the 20th century.

[00:04:17]I I had him as a professor in graduate school.

[00:04:19]>> Wow.

[00:04:20]>> Okay. In fact, I met my wife in relativity class that he was teaching.

[00:04:25]>> Cool.

[00:04:27]>> I was sitting in back row. She was in the front row.

[00:04:29]>> And then you guys made relatives.

[00:04:31]>> [laughter] >> What I can't quite wrap my head around is if gravity is just the curvature of space and time, maybe it's not a force.

[00:04:43]>> Okay.

[00:04:43]>> Cuz forces have these carrier particles.

[00:04:45]>> Right.

[00:04:46]>> And if you're just falling along a curvature of space and time, what does it even mean to think of that as a force?

[00:04:51]>> Right.

[00:04:52]>> Right. So, maybe it sits outside of the the quantum paradigms that would require that there be a graviton.

[00:04:58]>> Boy, that's something. That's kind of cool, man, in a way because that means that there would be something in between the quantum >> An understanding that we don't yet have.

[00:05:09]>> we don't have.

[00:05:10]>> Right. Right. Right. It's a frontier.

[00:05:12]>> Yeah, that's cool.

[00:05:14]>> All right.

[00:05:14]>> Well, there you go, buddy. I mean, listen. Now, you did some good That's a great question. This is John Mayer.

[00:05:20]>> I think it's Mayer or Maier.

[00:05:21]>> It's Maier.

[00:05:22]>> Uh m e i e r. M- Maier.

[00:05:26]>> Yeah.

[00:05:26]>> Yeah, John Maier. Salutations from John in Carlsbad, California.

[00:05:32]>> Carlsbad, California.

[00:05:34]>> California. He says, "Dr. Tyson and Lord Nice, the great defenders of art curiosity, I have a question that has plagued me >> Oh. That's a t-shirt if there ever was one.

[00:05:44]>> Yeah, the great >> StarTalk, the defenders of curiosity.

[00:05:48]He says, "As budgets seem to be one of the significant components of innovation in science."

[00:05:54]>> Yes.

[00:05:55]It's not a component of whether or not something is found to be true. It's a component of whether or not the research is conducted at all.

[00:06:07]>> Exactly.

[00:06:08]He says, "If we were to greatly increase the national or hypothetically the global science budget for building telescopes, what would you propose to maximize mankind's current technological possibilities, uh and what could they deliver in order to create the most powerful telescope possible? What would it look like? What would you point it at and what might we see?"

[00:06:30]>> Ooh, I would put an entire array of telescopes on the far side of the moon.

[00:06:35]>> Right.

[00:06:35]>> There's no atmosphere, so there's no clouds or anything. So, there's no value to be on a mountaintop. You don't even have There's no value to being in an orbit. The whole point of the orbit is you're outside the atmosphere. On the moon, there's no atmosphere, you're good. You're good to go. So, I put them all on the far side of the moon. And it doesn't even have to look towards Earth, where we have all of this contaminating radio wave noise and everything. I mean, Earth is just this messy thing in space.

[00:06:59]>> terrible. That's a great idea to put it on the far side of the moon though. To watch all put all the telescopes there.

[00:07:05]>> Yeah, and then I would you put of all bandwidths.

[00:07:07]>> Right.

[00:07:08]>> Of you put all the telescopes of all the windows of the electromagnetic spectrum.

[00:07:13]Radio waves.

[00:07:14]>> Everything.

[00:07:15]>> Everything. Everything.

[00:07:16]>> And now, what would you like to see?

[00:07:19]>> I want I'm ready for the next generation of telescope that can see gravitational waves and neutrinos that are not electromagnetic.

[00:07:28]>> Not electromagnetic. That would be fantastic.

[00:07:31]>> [music] [music] [music] [music] [music] >> Mhm.