Can Black Holes Break the Rules of Time?

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Discussion Overview

The discussion revolves around the nature of black holes, the possibility of time travel, and the implications of black hole physics on our understanding of time and dimensions. Participants explore theoretical concepts, challenge existing ideas, and propose speculative notions regarding the geometry of black holes and their effects on time.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions the possibility of time travel and the implications of achieving the speed of light, suggesting that nothing could maintain that speed.
  • Another participant asserts that backwards time travel is not possible and that traveling at the speed of light is also not feasible.
  • There is a discussion about the shape of black holes, with some participants stating that non-spinning black holes have a spherical event horizon due to their spherically symmetric nature, while spinning black holes may have a bulge at the poles.
  • Some participants propose that black holes emit Hawking radiation, although it is difficult to detect, and question how we can conclude that black holes are spherical if they do not emit radiation.
  • One participant suggests that the gravitational forces of black holes lead to their spherical shape, comparing them to larger celestial bodies that become more spherical as their mass increases.
  • Another participant introduces a speculative idea that entering a black hole might alter the dimensionality of matter and time, proposing that time could have multiple dimensions.
  • Concerns are raised about the role of the Milky Way's central black hole in attracting surrounding matter, with a participant questioning why it does not attract galactic planets.
  • There is a debate about the relevance of particle accelerators to time travel, with some asserting that they do not facilitate backward time travel.
  • One participant emphasizes that the event horizon is the only aspect of a black hole with meaningful geometry, distinguishing it from the singularity inside.
  • Another participant argues that the rules of physics do not break down at the singularity, suggesting that singularities may be excluded by undiscovered physical processes.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of black holes and time travel, with no consensus reached. Some agree on certain properties of black holes, while others contest these ideas and introduce alternative hypotheses.

Contextual Notes

Participants acknowledge limitations in observational evidence regarding the shape of black holes and the nature of singularities. There is also uncertainty regarding the implications of black holes on time and dimensions, with various assumptions and theoretical frameworks being discussed.

@$@D
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hey people..! I need to ask that whether time travel is possible ?.If speed of light is achieved..however besides this i also think that if speed of light is achieved nothing could stay at that speed virtually...what do you people think..??
Secondly, i was thinking that how do we know that BLACK HOLES are in a Circular Form.. i mean that it can be a shape less or even posses some other shape...
Also why can't we see a black hole as because the might emit some kind of radiations from them which can be used to plot an image or computer image of it..
 
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Backwards time-travel is not possible.
Traveling the speed of light is not possible.
The event horizon for a (non-spinning) black-hole is spherical because it is spherically symmetric, what determines the shape is only the distance away from it--which is constant.
Black holes are defined as the things that (themselves) can't emit radiation. They do emit radiation from their horizons, its too weak to detect.
 
Black holes emit hawking radiation, but, it is much cooler than the cmb. Sort of like trying to detect a star adjacent to the sun. Time travel is possible, but, only in one direction - the future. A black hole is defined by its event horizon. Only a schwardschild [non-spinning] black hole has a perfectly spherical event horizon. Kerr [spinning] black holes are believed to have a bulge in their event horizon [the poles are flattened]. It is highly probable the vast majority of, if not all, blacks holes spin.
 
Chronos said:
Only a schwardschild [non-spinning] black hole has a perfectly spherical event horizon. Kerr [spinning] black holes are believed to have a bulge in their event horizon [the poles are flattened]. It is highly probable the vast majority of, if not all, blacks holes spin.

It's worth noting that you can have black holes which do not correspond to a simple solution of a kerr-schild spinning hole. For example, immediately after two black holes merge the common hole is quite elongated and different. In such situations (really, in situations where there is any deviation from a stable state solution such as schwarzschild or more generally kerr-schild), the black hole will "oscillate", dominantly in a quadrupolar moment, and radiate away gravitational waves until it relaxes to a stationary solution. Basically, anything that's not spherically symmetric will soon become spherically symmetric.
 
Chronos said:
Black holes emit hawking radiation, but, it is much cooler than the cmb. Sort of like trying to detect a star adjacent to the sun. Time travel is possible, but, only in one direction - the future. A black hole is defined by its event horizon. Only a schwardschild [non-spinning] black hole has a perfectly spherical event horizon. Kerr [spinning] black holes are believed to have a bulge in their event horizon [the poles are flattened].

What of this did I not already say?
And the poles are not flatted, the schwarZSchild radius is the MINIMUM distance. For a spinning black hole, the event horizon is EXPANDED in the plane of rotation. Once on the subject (though fairly irrelevant to the initial question), an interesting note is that the side of the black-hole rotating towards an observer will appear larger than the other side. Check and mate.
 
zhermes said:
The event horizon for a (non-spinning) black-hole is spherical because it is spherically symmetric


Thats what i am asking that how do you know that it is spherical and symmetrical.when they don't emit any radiations and radiations from its horizon is very hard to detect ..then what has lead us to conclusion that black holes are spherical ...also If black holes are attracting things towards it. why isn't the milky way center black hole is attracting glaxcy planets...
secondly what about the Particle Acclerator .wont it give any help in time travelling...
 
@$@D said:
then what has lead us to conclusion that black holes are spherical

I suppose we have no observations to confirm that BH's are spherical, but a strong body of theory. Okay, here's a way to think about it:

A small asteroid is non-spherical because there isn't enough gravity to pull-it / mash-it into a sphere. Larger and larger asteroids, comets, moons become more and more spherical because their gravity gets stronger and stronger, and there are no forces which would lead to creating (significant) asymmetries.
Once you get to a star its VERY spherical, because that's the lowest energy configuration in a gravitational field. Once you're too massive to support yourself as a star, there is nothing preventing your collapse---and a spherically symmetric (for the most part) collapse into a black-hole. We know of no force to prevent the matter in a BH from shrinking to an infinitesimal point--so there's definitely (to our knowledge) nothing that would make it a-spherical.

The closer you get to a point, the more spherically symmetric you'll be. Black-holes are as close as you can get.
 
@$@D said:
also If black holes are attracting things towards it. why isn't the milky way center black hole is attracting glaxcy planets...
secondly what about the Particle Acclerator .wont it give any help in time travelling...

The BH at the center of the galaxy IS attracting everything towards it, that's part of why the galaxy remains bound together, and rotating nicely in a spiral--just like the planets around the sun.

Particle accelerators have nothing to do with time travel (before someone else chimes in: sure, the particles being accelerated move more slowly in time from an outside perspective, but still). You can't travel backwards in time.
 
Bear in mind we are talking about the event horizon, not the infinitesimal, singularity thing inside the event horizon. The event horizon is the only aspect of a black hole that has a meaningful geometry.
 
  • #10
Hi all,
This is just some food for thought that I have been contemplating for a while. We live in a universe with three dimensions of space and one dimension of time. Matter can only exist in three dimensions to our knowledge (and without getting into the micro) length, height and depth. When matter enters a black hole this rule, and physics, brakes. The other wise three dimensional matter becomes one dimensional, by this who is to say that the rolls are not simply switched? If matter is made into one dimension, then time might be made into three dimensions. Forwards, Backwards and alternate time lines.

When you take a multidimensional universe and force it to become one dimensional, or a singularity, just about every rule is broken. Why can't the same apply to time?
 
  • #11
arrow564 said:
Hi all,
This is just some food for thought that I have been contemplating for a while. We live in a universe with three dimensions of space and one dimension of time. Matter can only exist in three dimensions to our knowledge (and without getting into the micro) length, height and depth. When matter enters a black hole this rule, and physics, brakes.

Breaks. And, no, the 'rule' doesn't break. The singularity is where 'the rules' supposedly break down, but for that reason many physicists think singularities are excluded by physical processes we have yet to discover - that's the motivator for research into things like Quantum Gravity.

The other wise three dimensional matter becomes one dimensional, by this who is to say that the rolls are not simply switched?

'Spaghettification' doesn't mean the dimensions disappear, but that matter gets squeezed by intense tidal forces caused by space-time curvature very near the (supposed) singularity.

If matter is made into one dimension, then time might be made into three dimensions. Forwards, Backwards and alternate time lines.

No to the first bit, but there are theories which involve extra time dimensions, so who knows? Produce a physically observable consequence of that idea and you might unify GR & QM, as well as win a Nobel Prize.

When you take a multidimensional universe and force it to become one dimensional, or a singularity, just about every rule is broken. Why can't the same apply to time?

Again, doesn't happen as far as we currently know. And if it does, it happens behind an Event Horizon so that we can't see what happens...
 

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