Are Black Holes Actually Dark Energy Stars? • Hacker News Board

Re: Are Black Holes Actually Dark Energy Stars?

#61

Post by philipov » Wed, Oct 17, 2018, 8:39 PM UTC

lottin wrote: post #53

"The fabric of space-time" — I hear this a lot, but what does it mean? Does it mean that space and time are a "fabric"? What is such a fabric made of? The idea that space and time are actual objects, instead of intellectual constructs, has always struck me as wrong. (I'm not a physicist.)

It's usually referred to as a fabric because in general relativity, spacetime is dynamic, as if it were on a fabric that could stretch and contract in response to the density of matter occupying it. This is where the rubber-sheet analogy comes from.

As for what it is made of, that is one of the great open questions in theoretical physics right now, but also possibly where the analogy breaks down. Because of Lorentz Invariance (light travels at the same speed in all reference frames), it is hard to suppose that there is such a thing as "atoms of spacetime" from which it is made. However, because our world is cosmological and the big bang does actually pick out a preferred reference frame, Lorentz Invarience has to be approximate in some way.

Because of cosmology and the breakdown of reductionism at plank scales, it seems that the notion of spacetime itself is approximate and needs to be replaced with something else. Some people are trying to derive spacetime from purely quantum mechanical notions, while other people are trying to find dual systems where spacetime and quantum mechanics emerge hand-in-hand. The two approaches I'm familiar involve either holography or purely geometric and combinatorial ideas where the principles of general relativity and quantum mechanics are outputs rather than assumptions.

https://www.youtube.com/watch?v=WECVq2YBduY&t=0s&index=9&lis...

Re: Are Black Holes Actually Dark Energy Stars?

#62

Post by teilo » Wed, Oct 17, 2018, 8:41 PM UTC

sorenn111 wrote: post #58

Sarki wrote: post #52

On another note a theory which seems to fit particularly well is called Janus. The concept lies in the existence of a twin universe (ours being matter based the twin being antimatter based) merged together where the black holes are basically where the antimatter is concentrated and thus repulses all the matter hence this seemingly void. This is a succint summary but I hope it makes sense to the more knowledgeable rea…

The predominance of matter over antimatter I thought was explained by symmetry breaking at the ultra extreme conditions of early universe? Would there be a twin universe for other broken symmetries?

Symmetry breaking is an explanation, but we don't know if it's the right explanation. It's just the best we have at present.

Re: Are Black Holes Actually Dark Energy Stars?

#63

Post by JackFr » Wed, Oct 17, 2018, 8:41 PM UTC

doombolt wrote: post #39

HalcyonicStorm wrote: post #35

Earlier quoted context omitted.

I would argue that one of the reasons why physics news has been quiet is because the state of the field has moved beyond a lay person's understanding at more than a high level.

If you can't explain your idead to your janitor, you don't really grasp them yourself.

OTOH...

"Hell, if I could explain it to the average person, it wouldn't have been worth the Nobel prize." -- Richard Feynman

Re: Are Black Holes Actually Dark Energy Stars?

#64

Post by admax88q » Wed, Oct 17, 2018, 8:43 PM UTC

doombolt wrote: post #39

HalcyonicStorm wrote: post #35

Earlier quoted context omitted.

I would argue that one of the reasons why physics news has been quiet is because the state of the field has moved beyond a lay person's understanding at more than a high level.

If you can't explain your idead to your janitor, you don't really grasp them yourself.

The thing I hate about this statement is it gives people an excuse to ignore things they don't understand at first glace by claiming the presenter doesn't fully understand it so it's probably not true.

Its a good standard to hold yourself to when explaining things to others. But not one to hold others to when explaining to you.

Re: Are Black Holes Actually Dark Energy Stars?

#65

Post by ben_bai » Wed, Oct 17, 2018, 8:45 PM UTC

lottin wrote: post #53

"The fabric of space-time" — I hear this a lot, but what does it mean? Does it mean that space and time are a "fabric"? What is such a fabric made of? The idea that space and time are actual objects, instead of intellectual constructs, has always struck me as wrong. (I'm not a physicist.)

Fabric of spacetime is the name for the 4 dimensional "space" we live in/can observe. But the word space is already defined to 3 dimensions so better call it something else, like fabric.

Re: Are Black Holes Actually Dark Energy Stars?

#66

Post by pmalynin » Wed, Oct 17, 2018, 9:11 PM UTC

russdill wrote: post #55

This seems to try and make a parallel between neutron stars and his proposal of a "dark energy star". This uber-dense matter would stop matter from collapsing enough to form an event horizon. But there is a serious problem with this. If you measure the density of a black hole by using it's even horizon you'll find that the mass and event horizon do not scale together. For instance, calculated in this way, a galactic…

It actually is true thought, that some supermassive blackholes have a density thats pretty close to that of water, and their event horizons are very very gentle.

Re: Are Black Holes Actually Dark Energy Stars?

#67

Post by dsnuh » Wed, Oct 17, 2018, 9:13 PM UTC

btmiller wrote: post #54

lottin wrote: post #53

"The fabric of space-time" — I hear this a lot, but what does it mean? Does it mean that space and time are a "fabric"? What is such a fabric made of? The idea that space and time are actual objects, instead of intellectual constructs, has always struck me as wrong. (I'm not a physicist.)

Fabric in the sense that you cannot travel across space without also traveling across time.

>Fabric in the sense that you cannot travel across space without also traveling across time.

* Unless you happen to be a photon.

Re: Are Black Holes Actually Dark Energy Stars?

#68

Post by Semiapies » Wed, Oct 17, 2018, 9:16 PM UTC

joe-collins wrote: post #17

chc wrote: post #2

I've seen a couple of articles about this guy recently and they both struck me as weirdly credulous given the apparently complete lack of evidence supporting his theory and the fact that approximately no other scientists seem to find it credible.

At least at the pop-science level, his ideas connect a lot of dots. He'd neatly resolve the weirdness and mystery of black holes, their jets, their information paradox, and dark energy. It feels good. Whether or not any of it makes a lick of sense once you start actually crunching numbers is another question. The lack of interest from other scientists leaves me skeptical (even if I'm silently enamored of the neatness…

Yep. I've been hearing mentions of this guy's theories from pop science publications for years even though, as the article says, "The idea has found no support in the astrophysical community—over the last decade, Chapline’s papers on this topic have garnered only single-digit citations."

The pop science press is depressingly bad.

Re: Are Black Holes Actually Dark Energy Stars?

#69

Post by danarmak » Wed, Oct 17, 2018, 9:19 PM UTC

HalcyonicStorm wrote: post #35

diegoperini wrote: post #19

Earlier quoted context omitted.

If what LIGO achieved is not loud enough for the 21st century, then we are probably doomed. It is a NEW kind of telescope that has not even been utilized for 1% of its potential. PS: I'm not arguing with your statement, you have all the right to think that way. Maybe even people who lived during Einstein's earlier times thought the same for their previous century.

I would argue that one of the reasons why physics news has been quiet is because the state of the field has moved beyond a lay person's understanding at more than a high level.

Few non-physicists understand quantum mechanics even at a high level, but that certainly hasn't stopped journalists over the last hundred years. Whatever the new frontier is, I'm sure the popular media could cover it in technobabble just fine if they wanted to.

Re: Are Black Holes Actually Dark Energy Stars?

#70

Post by rsynnott » Wed, Oct 17, 2018, 9:20 PM UTC

diegoperini wrote: post #19

ChrisSD wrote: post #11

Earlier quoted context omitted.

After all the big discoveries (and personalities) of the 20th century, physics has seemed to be relatively quiet lately. So people are eager for the next big and dramatic change to our understanding. And that's what George Chapline is offering the pop sci press.

If what LIGO achieved is not loud enough for the 21st century, then we are probably doomed. It is a NEW kind of telescope that has not even been utilized for 1% of its potential. PS: I'm not arguing with your statement, you have all the right to think that way. Maybe even people who lived during Einstein's earlier times thought the same for their previous century.

I think people have been predicting gravity wave telescopes for so long that when one finally showed up, it wasn’t that exciting to the press.