/sci/ - Science & Math

>>7574359
>Does there have to be a graviton?
>Does their 'have' to be an atom???

fuck off with your antiscientific bullshit

>>7574359
It could. But the quest to "unify" forces has been a incredibly powerful driver of physics during the last two centuries or so. Why stop now ? Unless we can rigorously prove that gravity cannot be quantified, we must search for a way to do it.

>>7574359
Yes, there does have to be.

The universe can't just break and say "Well, fuck it, who knows" whenever very high energy densities show up. There has to actually be some rules it follows that govern exactly how it behaves in the case where both Gravity Shit and Very Small-Scale Shit are going down.

And if we were to write down these rules, we'd have a theory of quantum gravity, because it would predict both the effects of relativity (in the very large-scale and strong gravity case) and quantum mechanics (in the small scale, weak-gravity case), as well as what happens when both effects are relevant.

So yes, a theory of quantum gravity must exist.

No, there doesn't have to be a graviton; that's just the most immediately obvious way to make quantum gravity a thing.

>>7574380
>being this much of an unreflected physical realist

>>7574380
>The universe can't just break and say "Well, fuck it, who knows" whenever very high energy densities show up. There has to actually be some rules it follows....
There is absolutely nothing saying that it HAS to be this way. We just prefer to assume it is, because if that happens to be the case, then we have a chance of understanding it. So far, we've done pretty well with that assumption. But ultimately, all physics is empirical in nature, and that we can invent some math that works out basically every time we try it is a bonus.

>>7574408
No, the universe has to have order. We even have math to describe chaos, which is literally the most random concept possible. If something that follows much more general principles, such as gravity, breaks down somewhere, then there has to be a reason it breaks down. If there isn't, then we just haven't made good enough math to describe the situation.

>>7574380
>The universe can't just break and say "Well, fuck it, who knows" whenever very high energy densities show up.

Fucking funny way of putting it XD

>>7574366
>>7574368
>>7574380
I'm not saying there doesn't have to be a set of physical laws that the universe obeys - that goes without saying.

But it seems like so many of the problems with trying to reconcile quantum mechanics with relativity, trying to reconcile gravity with the other three forces, seems to come from the assumptions that follow from assuming they operate on fundamentally similar principles.

The problem is the theories are mutually exclusive. Quantum mechanics does not allow the well defined curvature of spacetime required by general relativity to exist. So, it isn't that we are hunting for gravitons, but that our theory of gravity just doesn't work if we have quantum mechanics.

>>7574359
There doesn't need to be a human made theory about them.
We could all just give up and let both sides evolve isolated from the other as their own branches that never meet.
But then... what is the point?
What is the point of studying the science that explains the universe to then not explain the universe by giving up and deciding "Well, that's it. Good job guys."

>>7574408
We do prefer to assume it is but we have reason to. If 4 thousand years of scientific progress has taught us anything in concrete is that everything can be explained.

If everything that we have observed until now can be explained then why do you think that the things that we are beginning to observe cannot be explained?

Seems illogical to me.

>>7574430
>seems to come from the assumptions that follow from assuming they operate on fundamentally similar principles.
It does indeed. And that's the point. Electricity and magnetism also operate on fundamentally similar principles.

>>7574430
Very interesting. Question everything. Even the questions you're asking. That is real science.

>>7574430
Sure, it's absolutely possible that gravity may not be quantized. But you can run into mathematical inconsistencies if you do that. There has to be some concession from one to the other, and vice-versa.

Still, candidate theories that keep gravity and quantum stuff on an almost totally different footing do also exist - most notably, semiclassical gravity. They have their own problems.

>>7574440
It's not so much questioning your questions, but rather your assumptions.

Case in point, taking a class in complex plasmas this semester and the professor teaching it just finished an entire series of lectures on the thermodynamics of dusty plasmas.

The most important topic he brought up was the fact that virtually ALL thermodynamics assumes a separable Maxwell Boltzmann distribution, however if you look at the original Maxwell papers they actually describe a tensor with off-axis coupling terms. When you factor these terms in they accurately replicate dust velocity distributions that the traditional MB distribution doesn't fit.


When you make an assumption you have to ask yourself whether or not that assumption is reasonable and supported by evidence. In this case, people simply assumed there was no coupling because that was the convention for the past century of thermal physics and it turned out that assumption was wrong.


It's not so unreasonable to think, then, that other assumptions... like say "all the fundamental forces must be described using the same mechanisms" could also be wrong.

>>7574380
>The universe can't just break and say "Well, fuck it, who knows" whenever very high energy densities show up.
your proof?

>>7574430
>I'm not saying there doesn't have to be a set of physical laws that the universe obeys - that goes without saying.
>that goes without saying.
No it doesn't. That "physical laws" and "rules" are some aspect of a "physical reality" and not just a feat of humans theories is not clear. So your notion might not be sensible.

>>7574475
>discussing system grounded in a rational, physical reality
>upset that assume rational, physical reality exists

>>7574465
>It's not so unreasonable to think, then, that other assumptions... like say "all the fundamental forces must be described using the same mechanisms" could also be wrong.
Yeah, for example it may be the case that the particle idea is sensible and realized in realize, but each individual particle in the universe, its motion and relation to other particles is governed by new individual laws as complicated as general relativity - maybe these theories would all be specifyable by some numbers (new numbers for each particle) or it's more complicated.
Now if the dynamics share some feats we could speak of statistical expectations, and at large scale we may not get a hint of the complicated reality. We would do physics for centuries before discovering that specifying the worlds dynamics properly is important, as we need lots of matter to even store the information about the matter in the universe. Physics, as performed by humans, would always remain at the modeling and averaging level.

The above is a scenario where I assume there are "real" physical rules (a new set of rules for each particle), but tbh this is also just wishful thinking - there may not be sensible rules in any sense that a human can comprehend.

>series of lectures on the thermodynamics of dusty plasmas.
You know the
https://en.wikipedia.org/wiki/BBGKY_hierarchy
The distributions get as goofy as you want.
(Further down the rabbit hole you find the Quantum Hierachy / Quantum Boltzmann Equation)

>>7574479
For any conclusion one would like to draw from the assumption that it exists, I'm certainly not upset at all about such an assumption.
But people here don't state it as an assumption just to reason from that perspective - it's presented as if we should take those nice starting points as certain fact

>>7574465
>It's not so unreasonable to think, then, that other assumptions... like say "all the fundamental forces must be described using the same mechanisms" could also be wrong.

For example it may be the case that the particle idea is sensible and realized in reality, but each individual particle in the universe, its motion and relation to other particles is governed by new individual laws as complicated as general relativity - maybe these theories would all be specifiable by some numbers (new numbers for each particle) or it's more complicated.

Now if the dynamics share some feats we could speak of statistical expectations, and at large scale we may not get a hint of the complicated reality. We would do physics for centuries before discovering that specifying the worlds dynamics properly is important, as we need lots of matter to even store the information about the matter in the universe. Physics, as performed by humans, would always remain at the modeling and averaging level.

The above is a scenario where I assume there are "real" physical rules (a new set of rules for each particle), but tbh this is also just wishful thinking - there may not be sensible rules in any sense that a human can comprehend.

>series of lectures on the thermodynamics of dusty plasmas.
You know the
https://en.wikipedia.org/wiki/BBGKY_hierarchy
The distributions get as goofy as you want.
(Further down the rabbit hole you find the Quantum Hierachy / Quantum Boltzmann Equation)

>>7574479
For any conclusion one would like to draw from the assumption that it exists, I'm certainly not upset at all about such an assumption.
But people here don't state it as an assumption just to reason from that perspective - it's presented as if we should take those nice starting points as certain fact