Black holes prove and disprove general relativity at the same time | Avshalom Elitzur

#einstein #physics #relativity

[bellateef]

Wow having Einstein on your show is something else 😮

[i_like-planes]

If I understood correctly,
General relativity isn't a complete theory but rather the best theory we've got right now?

[denniscarroll]

That's what makes science so interesting and fun. The answers create more questions and problems some times.

[jonahblock]

If i understand correctly, the wilder your hair is, the better you are at physics, and an accent always helps

[SamWestonJ]

Oh what a beautiful way to put it: the limitation of the theory is an invitation to elaborate. ❤

[nickadel]

This is explained so simply and directly and even completely better than most of what I've seen online until now

[shawns]

General Relativity predicts dilation wherever there is an astronomical quantity of mass, not singularities. In the 1939 journal "Annals of Mathematics" Einstein wrote -
"The essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of General Relativity predicting singularities) do not exist in physical reality. Although the theory given here treats only clusters (star clusters) whose particles move along circular paths it does seem to be subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light."
He was referring to the phenomenon of dilation. Mass that is dilated is smeared through spacetime relative to an outside observer. It's what our high school teachers were talking about when they said "mass becomes infinite at the speed of light". A graph illustrates its squared nature, dilation increases at an exponential rate the closer you get to the speed of light. A time dilation graph illustrates the same phenomenon, it's not just time that gets dilated.
Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. This includes the centers of very high mass stars and the majority of galaxy centers.
The mass at the center of our own galaxy is dilated. This means that there is no valid XYZ coordinate we can attribute to it, you can't point your finger at something that is smeared through spacetime. In other words that mass is all around us. This is the explanation for dark matter/galaxy rotation curves. The "missing mass" is dilated mass.

[TheNewPhysics]

Black Holes were predicted before Einstein was born.
An early idea related to black holes was proposed by John Michell in 1783, but it was not developed further at the time due to limitations in physics understanding.

[NatureSurfer]

To summarize the points, physics laws are regional laws in some sense, as long as you are within the region, the law applies perfectly, once you move to another region, different laws applies.

[stgo]

Indeed, still there are different amplitudes of "wronglyness". In the first case the theory would be completely wrong, in the second case it shows only a limitation but the track is correct. 😊

[Jotakumon]

A theory in physics is like a map of a part of the world. Locally, our planet is flat, so for a lot of intents and purposes, it is sufficient to do geometry as if the world was flat. As we expand our horizon, the curvature of the Earth becomes more apparent and affects our calculations more, and a new geometric model must be used to account for that. But in the end, the local geometry is still pretty damn good; for the right occasion.

[georgestuart]

I dont always like this guy but in the last statement, he captures the joy of science.
It is an invitation to inquire. Beautiful really.

[dasmith]

Relativity is a theory that appears to work perfectly in every area of the universe we can look at or visit (and still come back). The only place it "breaks down" is a place you can never examine. This is what experimentalists are constrained to call a pretty damn good theory. 😂

[jcb]

A singularity is a type of infinity. Infinities show the limitation of our math more than anything else.

[universeusa]

The statement that "if there are no black holes, then general relativity is wrong" oversimplifies a complex topic. Here are some key points to consider:

### 1. **General Relativity (GR) Overview**
- General relativity, formulated by Albert Einstein in 1915, describes gravity as the curvature of spacetime caused by mass and energy.
- It has been confirmed through numerous observations, including the bending of light, gravitational waves, and the precise movement of planets.

### 2. **Black Holes in GR**
- Black holes are solutions to the equations of general relativity, arising from the collapse of massive stars.
- They are characterized by an event horizon, beyond which nothing can escape.

### 3. **Existence of Black Holes**
- While black holes are a prediction of GR, their existence is supported by indirect evidence, such as the observation of gravitational waves from merging black holes and the motion of stars around invisible objects.
- The existence of supermassive black holes at the centers of galaxies is also well-supported.

### 4. **Alternatives to GR**
- If black holes were found not to exist, it would raise questions about specific aspects of GR, but it wouldn't necessarily invalidate the entire theory.
- Other models of gravity, such as those involving modifications to GR (e.g., loop quantum gravity, string theory), could potentially explain observations without requiring black holes.

### 5. **Scientific Inquiry**
- Science is always open to revision based on new evidence. If future observations suggest that black holes do not exist, it would lead to a re-evaluation of GR or the development of new theories.

### Conclusion
While the existence of black holes is a significant aspect of general relativity, their non-existence would challenge certain aspects of the theory rather than render it entirely incorrect. Science thrives on testing and refining theories based on empirical evidence, and general relativity remains one of the most successful theories in physics to date. 🤔

[Chazulu]

Infinities don't necessarily imply a broken theory. Indeed, when the "unreasonable" effectiveness of mathematics is considered, and the possibility for a diversity of cardinality and/or types of infinities exsists in mathematics, a reasonable perspective is that there is actually a noteworthy derth of infinities in scientific theories.

Indeed, given that the mathematics of black holes and time dilation allow for an infinite time internally to pass parallel to a finite external evaporation, who's to say that infinite universes per particle must not exist?

[petervandenengel]

In the perspective the two lines should also meet in a point. While they never do.

[davidwood]

There is a very high temperature inside the black hole . It’s in the nature of force inside the black hole .

[andrewadius]

That's what is so interesting about nature, and observations of nature.

[dinorex]

Exact reason I got interested in physics, it was like I’m a detective and I have these clues to solve a problem but then there more questions and problems that arise the deeper you look into it. Also, was that lady from crash course physics?