Loop Quantum Gravity predicts discrete, not continuous spacetime topology
sciam.com
sciam.com
The problem is that particle physics has a model that perfectly predicts every experiment we've done. However, it is aesthetically unappealing, and even more damning, we know it can't scale to explain everything in the universe. However, until one of our experiments actually does something unexpected, we're sort of twiddling our fingers.
In the video, the guy mentions that the worst case scenario for the LHC is to precisely confirm the standard model with no surprises. One person asks him something about what he'd do in that case (the question was muffled), and he replied that his reaction to this conundrum was to develop a sideline in quantum computing, since particle physics is really going nowhere until someone runs an experiment that contradicts the Standard Model.
In the meantime, a lot of other physicists spend their time spinning various weird, mutually-contradictory theories as a way to try to find an experiment they can run that would actually generate usable data. The continuous-vs-discrete reality question is scheduled to be investigated by a NASA satellite experiment at some point in the indefinite future, but who knows when it'll actually happen. In the meantime, we've got a lot of smart people stalled on having no (useful) data.
Meanwhile Chris King's Biocosmology, quantum loop gravity, orch OR, and doubly special relativity, all of which make really interesting predictions languish with not enough resources to study seriously, because string theorists dominate the academy.
We're at the same place now with our science as we were in the dark ages where scientists were called alchemists and had to sit in church and say the right outdated things in order not to be exiled or burned at the stake, basically.
Also, the seems to say that black holes are impossible.
But we don't have empirical evidence of black holes - we have circumstantial evidence of very dense blobs - they could be neutron stars or other things.
The reason they assume they are black holes is that if a neutron star was that big it would be a black hole - but if loop quantum gravity is right, then it would become a degenerate star instead and not a black hole.
Getting rid of black holes would help a lot BTW because they contradict a lot of well established theories, plus they can not be reconciled with relativity.
Here is the current state of evidence for black holes, from http://chandra.harvard.edu/chronicle/0307/onbh/
"Yet although thousands of bursts have been observed from neutron stars, not one has been observed from a black hole candidate. The lack of X-ray bursts from black hole candidates is a strong argument against the existence of gravastars and other exotic alternatives to black holes."
What "well established theories" do black holes contradict?
Black holes are predicted by relativity. How could they not be reconciled with it? http://en.wikipedia.org/wiki/Schwarzschild_metric
The main theoretical problem with black holes is the information loss due to the no hair theorem. Look up "Black hole unitarity".
Another problem is that hawking radiation can send out anything, with no regard to the quantum numbers of what when in - so you put in a proton and return photons, which normally is impossible (conservation of the baryon/lepton/parity number).
No one really knows it that will really happen though, it's all theories and ideas.
But a black hole is not so much a prediction of relativity as it's the point where relativity fails. In that sense it was predicted by it, but relativity can not explain what happens in a black hole.
Any clump of mass smaller than its own Schwarzchild radius will have an event horizon, but that doesn't necessarily mean that all that mass needs to wind up as a point. Under what we currently think we know about gravity a clump compressed to that radius will wind up as a singularity, but it's possible that we might have something wrong about gravity which would result in black holes with event horizons but no singularities -- instead you'd just have some high-but-not-infinite density mass in the middle being prevented from collapsing by... something we currently don't understand.
Because once gravity is that high going any higher has no meaning by any physics currently known. So by that definition once you crossed the event horizon anything inside has no meaning - and that is the singularity (i.e. the calculations of relativity have an infinity there, which is the singularity, not the mass in a point).
Also I did sort of assume that if matter can not collapse to a point a black hole is impossible. It does not appear that a quark star could be a black hole. And nothing is known about the other candidates listed on wikipedia (Preon star and Q star), but there sort of is the assumption that they could not make a black hole.
The article referenced for Q stars says 1.5 Schwarzschild radius, so it looks like to make a black hole you need a point mass.
I know Wikipedia isn't a good source for physics, but:
"While in a non-rotating black hole the singularity occurs at a single point in the model coordinates, called a "point singularity", in a rotating black hole, also known as a Kerr black hole, the singularity occurs on a ring (a circular line), defined as a "ring singularity". Such a singularity may also theoretically become a wormhole."
http://en.wikipedia.org/wiki/Gravitational_singularity
It seems a singularity is either a point or a line, but never a sphere for example.
For example relativity states that time stops totally past the event horizon, on top of that you can't even reach the event horizon because time dialates so much that you can never reach it - yet stuff falls in.
Or for example because length contracts based on speed it's possible for something to look like a black hole if you are moving fast, but not be a black hole if you are moving slow. That causes all sorts of contradictions.
Basically relativity can not calculate anything about the inside of a black hole.
How does length contraction make something "look" like a black hole? Gravitational force generated by an object cannot possibly change based on what an observer measures its length to be; No matter how fast or slow the observer is moving.
I don't know an awful lot of physics. For me, it appears that you are either intentionally throwing up random stuff to confuse others, or you are yourself confused. [No offense meant]
So if the object contracted and got really small, you could come very close to it and thus feel a gravitational force strong enough to act like a black hole.
Relativity cannot calculate anything "inside" a black hole because that's the regime where that particular theory breaks down. This is a feature of physics.
Why is the length contraction argument invalid? Just saying it's "invalid" doesn't help me much.
"Relativity cannot calculate anything "inside" a black hole because that's the regime where that particular theory breaks down. This is a feature of physics."
I said that didn't I? That was my point - that black holes break a theory, and there are no other theories to replace it. So not having black holes in the first place would help.
When you say feature do you mean "benefit" or "fact"? Because if you mean benefit I don't see how that is.
Please don't forget my original point: that if loop quantum gravity makes black holes impossible that is a plus for that theory. I'm not arguing about whether or not black holes exist, or if their math works.
We have images of stars rotating around some very dense invisible stuff. Too dense to be supported by neutron degeneracy. What more do you want? We can't exactly get pictures of the interior.
What we do have is pictures of gravitational lensing, and jets, and some other evidence, but certainly not stars rotating around dense stuff. And you are quite overestimating our ability to measure the size of the object - it could be very dense, but large, so not a black hole, but something else.
You quite missed the point - the whole point was that loop quantum gravity says that you can not get infinity dense, so even if neutron degeneracy can not hold it up, the loop quantum degeneracy will.
Perhaps quark degeneracy exists?
There is no evidence that black holes (as infinitely dense singularities) exists. There is only evidence of very big things, and our current theories don't know what else it could be. But that is NOT the same as evidence of a black hole.
In the "real" world the rules of information theory may or may not apply just as the rules of physics in a game may or may not apply in reality. So we cannot discern the probability of a simulated universe from whatever results may come from loop quantum gravity.
But my point was the loop quantum gravity says that spacetime is basically a matrix of pixels. Which is what I would expect if the world was a simulation.
It's not proof of course - there can't be proof, but if the world was continuous then it's less likely it's a simulation (but not impossible of course).
All I was trying to say (poorly) was that what you expect may have no relation to how the 'real' reality works. Digitization, pixels, etc. may have no analogue in actual existence and hence we cannot infer the nature of reality from our observations in simulation.
your seem to have a problem, that you use language wrong. your improper use of language causes you to be overly dogmatic in your thinking. 'The world is a simulation' 'spacetime is a matrix of pixels', what does that mean? All sentences of the form 'A is B' should be re-written 'A seems B to frame X' (or observer x).
loop quantum gravity does not say spacetime is pixels. it does say that spacetime might better be approximated as discrete at very small scales, and that such approximations might be useful tools for making progress. Recent experiments show that the idea that space is continuous at small scales is (make that, 'seems') an approximation. No one doing serious work on quantum anything thinks anything in the form X is Y. That worldview has been dead for 100 years. You can't play the speculate about quantum stuff game until you have changed your language to remove outmoded century old logical flaws you aren't aware of, which are built into the rules of a grammar you aren't conscious of, which governs the language you think in and predisposes you to make huge errors (like thinking there are cases where 'A is B').
You seem to think reality is actually one way, and our goal is to understand how reality is. That hasn't been the game for almost a hundred years. We now know that all models of reality, from physics to Aunt Edna's dogmatic catholicism, are tools that do not conform to reality. The idea is to refine our tools so they are more useful, not to figure out how reality is.
You need to drop some acid and read 'quantum psychology,' stat! The map is not the territory! The hand pointing at the moon is not the moon. The language that describes the map is not the territory it's even further from the territory. There is no meaning in life, because life is what meaning refers to. Looking for meaning in life is like looking for trees on a map. Looking for what reality is in quantum loop gravity is like looking for trees on a map.
To me that sounds like saying protons don't exist, it's just we can explain all sort of stuff by assuming they do.
If that really is the thinking in quantum physics it would explain a lot, but I think it's simply a cop-out because our intuitive sense does not work with the rules of quantum physics.
Thanks for posting this, it helps me put some strange papers on quantum physics in their proper perspective - they are not "this is what the world is", but rather "we found some cool math".
I guess that's what happens when you can't do experiments but can only make models and theories.
Far from being a cop-out, it's the bravest intellectual view you can take, and your only hope if you aren't down with the mathematics used in quantum physics. I wouldn't take it quite as far as reading the papers as only 'we found cool math'. Instead try 'we found experimental results such that no one set of mathematical models can (possibly!?) account for our experimental results."
The main confusion here arises from using the is of identity on reality. Reality is as described by this math. That's a case of confusing a reference and the thing refered to. That's calling a hand pointing at the moon the moon. Mathematics points to the structure of reality, but mathematics is not reality. Pointing to a theory understood in terms of language about mathematics about reality, and then saying "reality is that theory" is like pointing to a hand pointing to a hand pointing at the moon and saying "that hand is the moon."
You can't really get started correctly not understanding quantum physics until you get real clear on those differences. You can't get real clear on those differences while using the is of identity.
so it's not the source of all confusion in communication (I find poor communication is the fault of the person listening to me), but it is the source of the intuitions that make quantum physics seem counterintuitive, weird and mysterious.
Nonsense. Using sum when you don't mean sum is what causes problems. The ability to express such a thing isn't. Your complaint is that sum is being used express things that it doesn't properly mean, and your solution is to throw the word out altogether. Rather than taking the time to clarify what you mean, (English has perfectly good mechanisms for describing signifyers,) you blame the language and claim it needs to be changed.
What's particularly striking is the fact that you decry the dogmatism implied by sum, while at the same time being very dogmatic in doing so. In fact you used the word six times just now.
Using is or to be causes sloppy thinking, because you are cashing out your description of the universe without relativizing it to a frame. A seems B to instrument C, or A seems B relative to nervous system C. If you are talking about quantum physics, you can't discharge that. If you use the is of identity, your language discharges the observer as a feature. Quantum physics Fail.
This guy I was talking too seemed pretty interested in this stuff. If you want to take our science and apply what we learn to the world at large, then taking the language we use to talk about things in science (no is of identity in quantum physics equations or papers) and applying that grammar seems to me a very smart way to see the world more like science revels it.
It turns out this makes you sound exactly like a sufi or a zen monk a lot of the time, but that should surprise no one, since mysticism is a branch of neurology.
Robert Anton Wilson on 'To Be' and english without 'is' http://www.youtube.com/watch?v=kCIqFAdI6eI&feature=relat...
Robert Anton Wilson uses language (per above video) to explain quantum physics: http://www.youtube.com/watch?v=t5h2hC0pLvk
One of Protagoras' sayings is "man is the measure of all things."
"All sentences of the form 'A is B' should be re-written 'A seems B to frame X' (or observer x)."
We will never find the answer in our lifetime. We can't even concretely explain the process by which warm water sometimes freezes faster than cold water (Mpemba effect).
Things just get more complex and the human capacity for understanding is so limited in scope that when I read "The Big Bang may now be the Big Bounce" I have to laugh at our utter lack of intelligence.
Of course, this is not to denounce the scientific process or suggest that we scrap it altogether, maybe it should just serve as a good dose of humility to scientists who love to make fun of those who choose to follow a religion.
Religious people don't observe reality, they have already decided and when evidence suggests they are wrong they just don't take them into account(or worse, kills whoever suggested it). So no, science and religion are not by any means equal or comparable.
And how do you judge limited in scope of understanding? Compared to what? Do you know fo another world where they figured out how their universe worked much quicker and that universe was as complex as ours?