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  • Dark matter has been the go-to explanation for many scientists as to why there seems to be more gravitational influence in our universe than the gravity measured by visible matter.

  • But what if there's no dark matter at all?

  • The idea of dark matter was first proposed by Henri Poincaré in 1906.

  • Then in 1933, evidence of dark matter was found by Fritz Zwicky while studying galaxy clusters...

  • And then more evidence of dark matter was found based on the calculations of rotational velocities in galaxies made by Vera Rubin in 1978.

  • Our universe is made up of less than 5% of visible matter---like stars, planets, galaxies you, me, everything we can see.

  • Everything else, is stuff we can't see which we call dark matter.

  • And scientists think 95% of the matter in our universe is dark matter.

  • Right now, Dark Matter is used to explain a few pesky things in astrophysics.

  • Like

  • Why hot galaxy clusters don't blow themselves apart.

  • Why stars don't get flung out into space because of galaxy rotation.

  • And also, the temperature fluctuations of the CMB -- or cosmic microwave background radiation.

  • That said, there are theories that are trying to explain all this without assuming it's dark matte. These are: scale invariance and emergent gravity.

  • The empty space scale invariance theory says that properties of empty space should not change based on scale.

  • An astrophysicist looked back at the early equations of Einstein, and Newtonian Dynamics, and modified an acceleration term in Newton's law.

  • With this change, the law could explain a new force.

  • This force can explain things that were explained by dark mattersuch as holding a galaxy together that's spinning at high rotational velocities.

  • The only problem is, on Earth, this force can be up to billion times smaller than the force of gravity--making it difficult to measure.

  • It doesn't explain gravitational lensing, --which is the bending of light-- or the temperature fluctuations of the CMB.

  • The craziest, but to me the most interesting, is the holographic principle, which says that

  • our entire universe can be described on an imaginary sphere that surrounds ordinary matter.

  • It lead to the theory of emergent gravity.

  • That is the idea that gravity arises (or emerges) through the presence of matter.

  • This suggests this happens the same way temperature arises from the movement microscopic particles of matter.

  • So, if gravity is formed this way then it can be used to explain gravitational phenomena again!

  • Because something is keeping galaxies gravitationally bound.

  • It's possible that the force created in the emergent gravity theory does this!

  • But it still doesn't explain the CMB temperatures...

  • Scientists are still developing theories, like these, so they can explain things like the reason our universe hasn't completely blown apart because of invisible matter.

  • And they think it might be because of a gravitational field that developed through the movement of visible matter in our universe.

  • It's all very complicated, and yet, epic.

  • For the moment, arguments for dark matter still stand tall above many of these other theories, but hey, maybe not forever.

  • Hey peeps, take a sec to subscribe for more videos.

  • Plus, check out Trace's video about a new form of matter excitonium!

  • And one last fun fact: the holographic principle says we've always looked at life as 3 dimensions,

  • but if we looked at it as 2 dimensions then MAYBE the universe is just a holographic projection of ourselves.

  • Thanks for watching!

Dark matter has been the go-to explanation for many scientists as to why there seems to be more gravitational influence in our universe than the gravity measured by visible matter.


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ダークマターが存在しないとしたら? (What If Dark Matter Doesn't Exist?)

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    Jerry Liu に公開 2021 年 01 月 14 日