7 ms·

Loop Quantum Gravity predicts discrete, not continuous spacetime topology

27 points by Allocator2008 18y ago

river_styx 18y ago
So where are we now with physics, anyway? Converging on some kind of math/philosophy hybrid? Seems like as time goes by, these theories and constructs become more elaborate and abstract, which makes it ever less likely that we'll have the capability to test their predictions.
- LPTS 18y ago
  String Theory is great math but maybe you cant prove it, and maybe for any way the experiments turn out, you could provide an interpretation of string theory that supports it. 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science as we were in the dark ages where scientists were called alchemists and had to sit in church and say the right outdated things in order not to be exiled or burned at the stake, basically.
- jerf 18y ago
  Check out this Google Talk, "Why Physicists Need the Large Hadron Collider": http://www.youtube.com/watch?v=M8xwSfuY8xA http://www.youtube.com/watch?v=M8xwSfuY8xA 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.
rkowalick 18y ago
I find it interesting that the attempted theories to explain the makeup of matter seem quite ridiculous and almost humorous now. One would hope the theories about quantum gravity that are wrong will seem equally ridiculous in the future.
- LPTS 18y ago
  I hope you don't mean we should be using common sense and what seems ridiculous to our monkey brains as any sort of guide.
- jimbokun 18y ago
  I would say that the accepted theories seem quite ridiculous and humorous.
ars 18y ago
More proof that we live in the matrix. Seriously http://www.simulation-argument.com/ http://www.simulation-argument.com/ Also, the seems to say that black holes are impossible.
- hhm 18y ago
  That's a problem for them I guess... we have empirical evidence of black holes. Maybe what's impossible is singularities? Some physicist to correct me?
  - ars 18y ago
    A black hole is a singularity. 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.
    - nebula 18y ago
      plus they can not be reconciled with relativity. What do you mean? black holes indeed were a prediction of general relativity.
      - ars 18y ago
        They are only sort of a prediction, more accurately black holes are the point where the theory breaks down resulting in infinities (division by zero). 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.
kirse 18y ago
Does anyone else find this search to explain the creation of the universe hilariously futile? 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.
- schtog 18y ago
  Scientists observe reality and change the theory when the experimetns contradict it. 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?

27 points by Allocator2008 18y ago

So where are we now with physics, anyway? Converging on some kind of math/philosophy hybrid? Seems like as time goes by, these theories and constructs become more elaborate and abstract, which makes it ever less likely that we'll have the capability to test their predictions.

LPTS 18y ago
String Theory is great math but maybe you cant prove it, and maybe for any way the experiments turn out, you could provide an interpretation of string theory that supports it. 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.
jerf 18y ago
Check out this Google Talk, "Why Physicists Need the Large Hadron Collider": http://www.youtube.com/watch?v=M8xwSfuY8xA http://www.youtube.com/watch?v=M8xwSfuY8xA 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.

rkowalick 18y ago

I find it interesting that the attempted theories to explain the makeup of matter seem quite ridiculous and almost humorous now. One would hope the theories about quantum gravity that are wrong will seem equally ridiculous in the future.

LPTS 18y ago
I hope you don't mean we should be using common sense and what seems ridiculous to our monkey brains as any sort of guide.
jimbokun 18y ago
I would say that the accepted theories seem quite ridiculous and humorous.

ars 18y ago

More proof that we live in the matrix. Seriously http://www.simulation-argument.com/ http://www.simulation-argument.com/ Also, the seems to say that black holes are impossible.

hhm 18y ago
That's a problem for them I guess... we have empirical evidence of black holes. Maybe what's impossible is singularities? Some physicist to correct me?
- ars 18y ago
  A black hole is a singularity. 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.
  - nebula 18y ago
    plus they can not be reconciled with relativity. What do you mean? black holes indeed were a prediction of general relativity.
    - ars 18y ago
      They are only sort of a prediction, more accurately black holes are the point where the theory breaks down resulting in infinities (division by zero). 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.

kirse 18y ago

Does anyone else find this search to explain the creation of the universe hilariously futile? 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.

schtog 18y ago
Scientists observe reality and change the theory when the experimetns contradict it. 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?