5 ms·

GR and quantum field theory don't work together, so at least one of them is wrong, and it would be good to figure out which and how.

jeremyjh 5y ago
Why would that matter at this scale ?
- dotnet00 5y ago
  Black holes are extreme enough to be one of the places where both can matter.
  - jeremyjh 5y ago
    Scale was not the right word - maybe I meant distance or resolution. Does QM make a prediction that could be falsified at this resolution?
markus_zhang 5y ago
Thanks. Can you please point me to some popular science article that explains why the two do not agree with each other?
- boschnix 5y ago
  I liked Sean Carroll's take on this with Steven Strogatz in the recent episode of Joy of Why. https://www.quantamagazine.org/where-do-space-time-and-gravity-come-from-20220504/ https://www.quantamagazine.org/where-do-space-time-and-gravi...
- rootbear 5y ago
  Brian Greene's "The Elegant Universe" does a very good, completely non-technical, job of explaining the conflict between the two theories. It then goes on to explain why String Theory is one possible solution to the problem.
  - markus_zhang 5y ago
    Perfect! Thank you.
  - zeven7 5y ago
    There's also a Nova documentary version if parent would prefer to watch something: https://www.pbs.org/wgbh/nova/series/the-elegant-universe/ https://www.pbs.org/wgbh/nova/series/the-elegant-universe/ I'll add an additional recommendation: Stephen Hawking - The Theory Of Everything
- tzs 5y ago
  Here are a few that might help: https://gizmodo.com/why-cant-einstein-and-quantum-mechanics-get-along-799561829 https://gizmodo.com/why-cant-einstein-and-quantum-mechanics-... https://www.theguardian.com/news/2015/nov/04/relativity-quantum-mechanics-universe-physicists https://www.theguardian.com/news/2015/nov/04/relativity-quan... https://en.wikipedia.org/wiki/Problem_of_time https://en.wikipedia.org/wiki/Problem_of_time https://physics.stackexchange.com/questions/387/a-list-of-inconveniences-between-quantum-mechanics-and-general-relativity https://physics.stackexchange.com/questions/387/a-list-of-in... For a good general source if you want to learn a lot more from a good popular science point of view (but one that takes great care to not accidentally mislead by oversimplification as often happens with popular science) about general relativity and quantum mechanics, try PBS Space Time, especially after Dr. Matt O'Dowd took over as host and main writer. https://www.youtube.com/c/pbsspacetime https://www.youtube.com/c/pbsspacetime
- GoblinSlayer 5y ago
  tl;dr they don't conflict with each other, they conflict with a third assumption that particles have zero size. GR suggests they would be black holes, and those have mathematical difficulties. String theory is an attempt to model particles of finite size and thus eliminate black holes.
ckosidows 5y ago
You're saying this team has proven neither of them wrong in that their findings agree with GR, is that correct? Essentially, nothing new has been learned about these two theories?
- colechristensen 5y ago
  GR and QFT essentially have to meet at black holes and this is where you’d expect to find an anomaly with ought to help open doors to new physics, but what we see here is that this observation seems to still obey GR just fine and a a closer look will be necessary to find any anomaly. It might just not be possible to see anything odd without having a black hole right there to study, but there’s always hope that the next new observation will provide a clue as the previous ones repeatedly have not.
perardi 5y ago
so at least one of them is wrong This is a semantic nitpick, but I don’t think it’s useful to think of these theories as “wrong”. They are both models that make predictions about physical phenomena that, when tested, are extremely accurate. They provide incomplete and inconsistent predictions of what happens at the very edges of physical reality, and they need reconciled.

jeremyjh 5y ago

Why would that matter at this scale ?

dotnet00 5y ago
Black holes are extreme enough to be one of the places where both can matter.
- jeremyjh 5y ago
  Scale was not the right word - maybe I meant distance or resolution. Does QM make a prediction that could be falsified at this resolution?

markus_zhang 5y ago

Thanks. Can you please point me to some popular science article that explains why the two do not agree with each other?

boschnix 5y ago
I liked Sean Carroll's take on this with Steven Strogatz in the recent episode of Joy of Why. https://www.quantamagazine.org/where-do-space-time-and-gravity-come-from-20220504/ https://www.quantamagazine.org/where-do-space-time-and-gravi...
rootbear 5y ago
Brian Greene's "The Elegant Universe" does a very good, completely non-technical, job of explaining the conflict between the two theories. It then goes on to explain why String Theory is one possible solution to the problem.
- markus_zhang 5y ago
  Perfect! Thank you.
- zeven7 5y ago
  There's also a Nova documentary version if parent would prefer to watch something: https://www.pbs.org/wgbh/nova/series/the-elegant-universe/ https://www.pbs.org/wgbh/nova/series/the-elegant-universe/ I'll add an additional recommendation: Stephen Hawking - The Theory Of Everything
tzs 5y ago
Here are a few that might help: https://gizmodo.com/why-cant-einstein-and-quantum-mechanics-get-along-799561829 https://gizmodo.com/why-cant-einstein-and-quantum-mechanics-... https://www.theguardian.com/news/2015/nov/04/relativity-quantum-mechanics-universe-physicists https://www.theguardian.com/news/2015/nov/04/relativity-quan... https://en.wikipedia.org/wiki/Problem_of_time https://en.wikipedia.org/wiki/Problem_of_time https://physics.stackexchange.com/questions/387/a-list-of-inconveniences-between-quantum-mechanics-and-general-relativity https://physics.stackexchange.com/questions/387/a-list-of-in... For a good general source if you want to learn a lot more from a good popular science point of view (but one that takes great care to not accidentally mislead by oversimplification as often happens with popular science) about general relativity and quantum mechanics, try PBS Space Time, especially after Dr. Matt O'Dowd took over as host and main writer. https://www.youtube.com/c/pbsspacetime https://www.youtube.com/c/pbsspacetime
GoblinSlayer 5y ago
tl;dr they don't conflict with each other, they conflict with a third assumption that particles have zero size. GR suggests they would be black holes, and those have mathematical difficulties. String theory is an attempt to model particles of finite size and thus eliminate black holes.

ckosidows 5y ago

You're saying this team has proven neither of them wrong in that their findings agree with GR, is that correct? Essentially, nothing new has been learned about these two theories?

colechristensen 5y ago
GR and QFT essentially have to meet at black holes and this is where you’d expect to find an anomaly with ought to help open doors to new physics, but what we see here is that this observation seems to still obey GR just fine and a a closer look will be necessary to find any anomaly. It might just not be possible to see anything odd without having a black hole right there to study, but there’s always hope that the next new observation will provide a clue as the previous ones repeatedly have not.

perardi 5y ago

so at least one of them is wrong This is a semantic nitpick, but I don’t think it’s useful to think of these theories as “wrong”. They are both models that make predictions about physical phenomena that, when tested, are extremely accurate. They provide incomplete and inconsistent predictions of what happens at the very edges of physical reality, and they need reconciled.