5 ms·

"Nothing can go faster than light" is just a convention and is not experimentally confirmed. IIRC there are a few things that go faster than speed of light (e.

"Nothing can go faster than light" is just a convention and is not experimentally confirmed. IIRC there are a few things that go faster than speed of light (e.g. universe expanding). "Spooky action at a distance" is also not known very well. That could also break the speed of causality law. While Bell's theorem hints that this is not the case, there are some exceptions to Bell's theorem. Right now a lot in physics are just convention like energy conservation and symmetry. We need another paradigm upgrade to understand these things.

Choc13 5y ago
Hmm not sure if troll, but energy conservation is definitely not just some convention. It’s a fundamental thermodynamic law. Spooky action at a distance does not violate speed of light information propagation either. The particles have to be entangled before they’re set off in opposite directions. Only once one is observed does the other also collapse, but it doesn’t mean you can communicate faster than the speed of light because you had to prepare the information when the particles were together IIRC, it’s been a decade since I studied quantum information theory.
- ergocoder 5y ago
  Why do you feel the need to say somebody is a troll? Here: https://phys.org/news/2017-01-violations-energy-early-universe-dark.html https://phys.org/news/2017-01-violations-energy-early-univer... Here: https://phys.org/news/2015-02-space-faster.html https://phys.org/news/2015-02-space-faster.html - we are trying hard to reconcile this and categorize universe expanding as something else (e.g. not a movement that has speed because time itself is a dimension or something). But this is still up for debate, tbh. Another example was one where we said CP symmetry was true (it was a law like a lot of things in physics) until it was violated by a weak nuclear force experiment. And now we are holding the fort at CPT symmetry as the law. In Physics, the evidence of anything is kinda light. A lot of reasonable extrapolations has been made. Still they are extrapolations (e.g. intelligent guess). Even the big bang itself is just an extrapolation from the "theory" that the universe expanding. To be fair, it is difficult to find good evidence because we can't dial back time, can't go observe things on Neptune, can't measure gravity at the subatomic scale, and etc. So, we have to work with what we can experimentally observe. Our tools are getting better, and this is where the physics paradigm shift will come from. You say like these are 100%. It is just a theory that we currently hold according to the little evidence that we have. Failing to recognize that is straight up unscientific.
  - Choc13 5y ago
    Apologies, I wasn’t trying to call you a troll, more that your first comment seemed to me like it might have been made in jest, clearly it wasn’t. The articles you’ve linked to are interesting and there are clearly many scientific discoveries to be made by studying the early formation of the universe which will test our current models. However I don’t feel like convention is the right word for laws like the conservation of energy, even if there are some difficulties with tying up these theories and new experimental evidence from events at the scale of the Planck length. Convention to me would mean something that has been accepted just because it’s always been done that way and people didn’t really bother to question why, but I don’t think that’s the case here. But we’re verging on pedantry now so no point going down that route any further.
    - deltasixeight 5y ago
      >Convention to me would mean something that has been accepted just because it’s always been done that way and people didn’t really bother to question why. You're wrong. The Thermodynamic laws are sort of axiomatic, meaning you really can't explain why energy is conserved. It's just experimentally shown to be maybe true, but no one knows why energy is conserved or has actually proved it to be true. It is totally "convention" as you defined it. The caveat here is that entropy is not axiomatic. Entropy occurs as a consequence of probability. Probability is the real axiomatic assumption of the universe and entropy is a byproduct. The thermodynamic laws were established before people fully understood the true nature of what was going on with entropy so these laws are sort of a hodge podge of axioms and derived theorems. From a temperature perspective these assumptions work so the laws still have their use. But the laws of thermodynamics aren't some elegant grouping of fundamental laws of the universe. It is a set of rules that are grouped arbitrarily. >But we’re verging on pedantry now so no point going down that route any further. I find this attitude rude. You called him a troll than apologized then gave your final answer and dismissed any further discussion as "pedantry." Like wow, you get the last word and shut down anything else he has to say? You were rude to assume he was in jest and you're being rude again by saying any further discussion after your final statement is pedantry. Either way I disagree with you. It's not pedantry. This discussion is about convention and the conservation of energy. Your statement is wrong.
hyperman1 5y ago
AFAIK 'nothing goes faster than c' is wrong in the 'lies to children category'. The devil is in the details. In fact, plenty of things go faster than c. As a standard example, take a wall at 1m distance and a flashlight. move the light spot at 1 m/s. If you put the wall at 2m, the same spot will now go 2 m/s. If you put it at 300 000 km, the spot will go at 300 000 km/s, slightly over light speed. The problem is more one of information: For any action you take, no consequence can happen outside your light cone. All information you generate travels at c at max. None of the examples you gave violates this: Even if the universe expands at more than c, nothing you do will have influence on things too far from you.
- ergocoder 5y ago
  That is a reasonable argument. And what you point out is actually the speed limit of causality, instead of light. It just happens that light travel really fast. Though the article wants to discuss the speed of light as you mentioned, so I focused on speed of light.
- mewse 5y ago
  That's not the "same" spot, though. It doesn't consist of the same photons; the spot in the "new" position consists of photons which have been traveling in a straight line from your flash light at (assuming vacuum) a constant rate of C (and then reflected back to reach your eye again, also at a constant rate of C); they haven't traveled to or from the previous "spot" position at all, much less exceeded the speed of light at any point in the process of reaching the new position. Right?
  - hyperman1 5y ago
    That's correct in both the superluminal and the subluminal case, and more or less the point of the example. The spot moves superluminal, but the particles creating it don't. This makes it impossible to use it for superluminal information transfer. AFAIK Expansion of the universe is comparable. It pushes things away not by speed but by putting extra 'new' space between things. Your sibling comment makes a variant of the same point:c is the maximal speed of information or causality. Light in a vacuum is just one of the things capable of reaching it.

Choc13 5y ago

Hmm not sure if troll, but energy conservation is definitely not just some convention. It’s a fundamental thermodynamic law. Spooky action at a distance does not violate speed of light information propagation either. The particles have to be entangled before they’re set off in opposite directions. Only once one is observed does the other also collapse, but it doesn’t mean you can communicate faster than the speed of light because you had to prepare the information when the particles were together IIRC, it’s been a decade since I studied quantum information theory.

ergocoder 5y ago
Why do you feel the need to say somebody is a troll? Here: https://phys.org/news/2017-01-violations-energy-early-universe-dark.html https://phys.org/news/2017-01-violations-energy-early-univer... Here: https://phys.org/news/2015-02-space-faster.html https://phys.org/news/2015-02-space-faster.html - we are trying hard to reconcile this and categorize universe expanding as something else (e.g. not a movement that has speed because time itself is a dimension or something). But this is still up for debate, tbh. Another example was one where we said CP symmetry was true (it was a law like a lot of things in physics) until it was violated by a weak nuclear force experiment. And now we are holding the fort at CPT symmetry as the law. In Physics, the evidence of anything is kinda light. A lot of reasonable extrapolations has been made. Still they are extrapolations (e.g. intelligent guess). Even the big bang itself is just an extrapolation from the "theory" that the universe expanding. To be fair, it is difficult to find good evidence because we can't dial back time, can't go observe things on Neptune, can't measure gravity at the subatomic scale, and etc. So, we have to work with what we can experimentally observe. Our tools are getting better, and this is where the physics paradigm shift will come from. You say like these are 100%. It is just a theory that we currently hold according to the little evidence that we have. Failing to recognize that is straight up unscientific.
- Choc13 5y ago
  Apologies, I wasn’t trying to call you a troll, more that your first comment seemed to me like it might have been made in jest, clearly it wasn’t. The articles you’ve linked to are interesting and there are clearly many scientific discoveries to be made by studying the early formation of the universe which will test our current models. However I don’t feel like convention is the right word for laws like the conservation of energy, even if there are some difficulties with tying up these theories and new experimental evidence from events at the scale of the Planck length. Convention to me would mean something that has been accepted just because it’s always been done that way and people didn’t really bother to question why, but I don’t think that’s the case here. But we’re verging on pedantry now so no point going down that route any further.
  - deltasixeight 5y ago
    >Convention to me would mean something that has been accepted just because it’s always been done that way and people didn’t really bother to question why. You're wrong. The Thermodynamic laws are sort of axiomatic, meaning you really can't explain why energy is conserved. It's just experimentally shown to be maybe true, but no one knows why energy is conserved or has actually proved it to be true. It is totally "convention" as you defined it. The caveat here is that entropy is not axiomatic. Entropy occurs as a consequence of probability. Probability is the real axiomatic assumption of the universe and entropy is a byproduct. The thermodynamic laws were established before people fully understood the true nature of what was going on with entropy so these laws are sort of a hodge podge of axioms and derived theorems. From a temperature perspective these assumptions work so the laws still have their use. But the laws of thermodynamics aren't some elegant grouping of fundamental laws of the universe. It is a set of rules that are grouped arbitrarily. >But we’re verging on pedantry now so no point going down that route any further. I find this attitude rude. You called him a troll than apologized then gave your final answer and dismissed any further discussion as "pedantry." Like wow, you get the last word and shut down anything else he has to say? You were rude to assume he was in jest and you're being rude again by saying any further discussion after your final statement is pedantry. Either way I disagree with you. It's not pedantry. This discussion is about convention and the conservation of energy. Your statement is wrong.

hyperman1 5y ago

AFAIK 'nothing goes faster than c' is wrong in the 'lies to children category'. The devil is in the details. In fact, plenty of things go faster than c. As a standard example, take a wall at 1m distance and a flashlight. move the light spot at 1 m/s. If you put the wall at 2m, the same spot will now go 2 m/s. If you put it at 300 000 km, the spot will go at 300 000 km/s, slightly over light speed. The problem is more one of information: For any action you take, no consequence can happen outside your light cone. All information you generate travels at c at max. None of the examples you gave violates this: Even if the universe expands at more than c, nothing you do will have influence on things too far from you.

ergocoder 5y ago
That is a reasonable argument. And what you point out is actually the speed limit of causality, instead of light. It just happens that light travel really fast. Though the article wants to discuss the speed of light as you mentioned, so I focused on speed of light.
mewse 5y ago
That's not the "same" spot, though. It doesn't consist of the same photons; the spot in the "new" position consists of photons which have been traveling in a straight line from your flash light at (assuming vacuum) a constant rate of C (and then reflected back to reach your eye again, also at a constant rate of C); they haven't traveled to or from the previous "spot" position at all, much less exceeded the speed of light at any point in the process of reaching the new position. Right?
- hyperman1 5y ago
  That's correct in both the superluminal and the subluminal case, and more or less the point of the example. The spot moves superluminal, but the particles creating it don't. This makes it impossible to use it for superluminal information transfer. AFAIK Expansion of the universe is comparable. It pushes things away not by speed but by putting extra 'new' space between things. Your sibling comment makes a variant of the same point:c is the maximal speed of information or causality. Light in a vacuum is just one of the things capable of reaching it.