Not a physicist either but my understanding is that is that if you believe that we can discover all the laws of physics that explain how the world operates then it needs to have a solution.
Like we have formulas describing how gravity works. We can test these formulas by observing the motion of the planets and galaxies. Is this theory true? There's lots of evidence for it so it feels like it's gotta be pretty close to "the truth"
We also have formulas describing how elementary particles behave. These formulas have been tested to a very high degree of precision so it seems they've got to be close to the truth as well. But if you use both our formulas for gravitation and formulas for elementary particles you can derive a contradiction. So these two theories cannot simultaneously be true. There's got to be something wrong with them.
I suppose there's the possibility that at a certain point nature simply doesn't follow any laws and you can't possibly make sense of it.
According to Sabine Hossefelder, there's no scientific basis to expect that a theory of everything exists (if I remember correctly this blog post) [1]. But I also have to say that, while I do find interesting what she talks about and I agree with her about some problems in academia she often complains about, for this very reason some other physicists don't like her and say she's wrong. But my understanding is that she still gets the Physics and Math parts right, it is her complaints about academia that some academics strongly disagree with.
Well, the universe does something with extremely small but extremely heavy objects, unless you think that merely creating that situation will cause the universe to cease to exist.
You don’t even need that to understand the tension between QM and GR:
What is the gravitational field of a particle in a superposition of two different locations? What about when the superposition collapses? Does the gravity field instantly change shape, faster than light?
The consensus right now is this is so hard to measure we’ll basically never know the answer from just observations. Maybe having a gravitational influence on something at all, collapses the superposition? Maybe if you put the particles in a large enough configuration it’s impossible to maintain superposition? Maybe there’s enough background noise in our particular universe to make such a measurement permanently impossible, and we get by on a technicality? Nobody knows.
> What is the gravitational field of a particle in a superposition of two different locations? What about when the superposition collapses? Does the gravity field instantly change shape, faster than light?
This is a symptom of the problem of gravity/spacetime being a handled as a classical field, not really the problem itself. The electromagnetic field for example has this exact same problem, but it's handled by the electromagnetic field being quantized. The problem is that nobody is able to fully quantize gravity.
Now consider that the density of an atomic nucleus is oddly similar to the density of a black hole. And this was the path Einstein was following. Too bad you need computers to study it because of all the differential equations.
Well nature follows general relativity and quantum mechanics so presumably they can co-exist. We just don't have a mathematically consistent theory as to how.
So we do know that all the tiny interactions like charge of particles etc must work side by side with all the big interactions like gravity as otherwise how would anything as we know it work. However it could as easily be neither are the right way to interpret the world and there is something we are missing, or we are right and we can find a method to combine the theory of the big and the small interactions but we are missing a section. At the end of the day we can't interact in any meaningful way with more than half the matter in the universe (it's proven to exist due to a gravitational pull), so it's clear we can't experience a lot of the universe and we definitely can't explain a lot.
So yes there is a solution, but do we, as humans, have the ability to come up with it, who knows. I would say it's unlikely.
Not a physicist either but my understanding is that is that if you believe that we can discover all the laws of physics that explain how the world operates then it needs to have a solution.
Like we have formulas describing how gravity works. We can test these formulas by observing the motion of the planets and galaxies. Is this theory true? There's lots of evidence for it so it feels like it's gotta be pretty close to "the truth"
We also have formulas describing how elementary particles behave. These formulas have been tested to a very high degree of precision so it seems they've got to be close to the truth as well. But if you use both our formulas for gravitation and formulas for elementary particles you can derive a contradiction. So these two theories cannot simultaneously be true. There's got to be something wrong with them.
I suppose there's the possibility that at a certain point nature simply doesn't follow any laws and you can't possibly make sense of it.
According to Sabine Hossefelder, there's no scientific basis to expect that a theory of everything exists (if I remember correctly this blog post) [1]. But I also have to say that, while I do find interesting what she talks about and I agree with her about some problems in academia she often complains about, for this very reason some other physicists don't like her and say she's wrong. But my understanding is that she still gets the Physics and Math parts right, it is her complaints about academia that some academics strongly disagree with.
[1] https://backreaction.blogspot.com/2020/07/do-we-need-theory-...
Well, the universe does something with extremely small but extremely heavy objects, unless you think that merely creating that situation will cause the universe to cease to exist.
You don’t even need that to understand the tension between QM and GR:
What is the gravitational field of a particle in a superposition of two different locations? What about when the superposition collapses? Does the gravity field instantly change shape, faster than light?
The consensus right now is this is so hard to measure we’ll basically never know the answer from just observations. Maybe having a gravitational influence on something at all, collapses the superposition? Maybe if you put the particles in a large enough configuration it’s impossible to maintain superposition? Maybe there’s enough background noise in our particular universe to make such a measurement permanently impossible, and we get by on a technicality? Nobody knows.
> What is the gravitational field of a particle in a superposition of two different locations? What about when the superposition collapses? Does the gravity field instantly change shape, faster than light?
This is a symptom of the problem of gravity/spacetime being a handled as a classical field, not really the problem itself. The electromagnetic field for example has this exact same problem, but it's handled by the electromagnetic field being quantized. The problem is that nobody is able to fully quantize gravity.
Not all interpretations of QM have collapses, which tend to be underdescribed even in purely QM terms.
Now consider that the density of an atomic nucleus is oddly similar to the density of a black hole. And this was the path Einstein was following. Too bad you need computers to study it because of all the differential equations.
Well nature follows general relativity and quantum mechanics so presumably they can co-exist. We just don't have a mathematically consistent theory as to how.
So we do know that all the tiny interactions like charge of particles etc must work side by side with all the big interactions like gravity as otherwise how would anything as we know it work. However it could as easily be neither are the right way to interpret the world and there is something we are missing, or we are right and we can find a method to combine the theory of the big and the small interactions but we are missing a section. At the end of the day we can't interact in any meaningful way with more than half the matter in the universe (it's proven to exist due to a gravitational pull), so it's clear we can't experience a lot of the universe and we definitely can't explain a lot.
So yes there is a solution, but do we, as humans, have the ability to come up with it, who knows. I would say it's unlikely.