/sci/ - Science & Math

no. quantum mechanics are the new standard i think, because einsteins theories didnt make sense on the small stuff. basically things happen randomly, not according to e=mc2 and other equations.

>>972838
>General and Special relativity still consider to be the basis for modern physics

Well they were never thrown our, but
they aren't the basis. I don't think they were ever the basis. The term
modern" usuall refers to QM, and eveything after that. SR is usually considered Classical Phyics. Its "Classical Field theory" .

>>972876
So there has been nothing major to discredit the ideas, despite incompatibility with quantum mechanics?

lol einstein

It was my impression that QM was used for really small things like atoms but general relativity was used for large scale things.

>>972868
bullshit

>>972868

don't talk about things you have no idea about.

the standard model is the basis for modern physics. GR and SR are both valid for non-quantum scales of course, and are also very accurate (think time corrections on GPS satellites)

>>972885
Has there been given a scientific reason as to why 'small scale' and 'large scale' things behave differently, and what is the cut-off point for large and small. In terms of the Universe, why should something small behave differently from something large?

>>972882
No, nothing major. They aren't "wrong", but they are now seen as incomplete. It's just like Newton's laws--they still "work," they just have limits.

>>972889
how about you don't talk about things you dont know. i'm doing final grade physics at high school at getting A's, we even watched a video on the discovery of quantum mechanics and easteins theorys were largely proven wrong

>>972892
Gravity is a pushing force not a pulling force

>>972868
>>972868
No, you have no idea what you are talking about. You an enginigger?

>>972889
Standard model uses special relativity.

>>972882
Relativity is not incompatible with quantum mechanics. There is an entire field called relativistic quantum mechanics.

>>972892
>Has there been given a scientific reason as to why 'small scale' and 'large scale' things behave differently
On the small scale, the reason is that energy is "doled out" in discrete chunks rather than on a continuum.

On the large scale, no one has solid ideas. Look up space inflation, dark matter, dark energy, and dark flow.

>>972838
On the macro scale, they are mandatory. GPS for example wouldn't work without knowledge of both Special and General Relativity.

>>972893
Awesome. Thanks.

Still a bit lost on this though:
>>972892

Never was strong with physics but I have a mild interest. Any recommended reading. Mid difficulty and something a tad harder once I've built a better understanding?

>>972905
But what is the characteristic that determines why energy is dealt out differently on a smaller level? Why does the size of a specific piece of matter suddenly change it's behaviour?

>>972882
Ohh, you seem to have a problem understanding the "range of valididty". All physics, every field, only has a certain range it works for.

GR and SR are just fine for there ranges. GR has a much differnt range then QM though, hence we would never even try to use GR and QM together.

SR and QM work just fine together. There range of validity overlaps.

>>972900
DSJHAFKLJH§UR=)/(
.

Everything that involves a spin in quantum physics is relativistic. It's also not a classical field theory.

>>972912
>But what is the characteristic that determines why energy is dealt out differently on a smaller level?
"Why" is unknown. M theory postulates reasons for it, I believe. But ignoring the "why", we experimentally observe it. Look up the photoelectric effect.

>>972892
No idea on what the "cut off point" would be exactly, but I believe that the reason why we need quantum mechanics for atoms and sub-atomic particles is because on that small a scale wierd shit starts happening. Ask someone who knows more about this than me what kind of stuff does happen but there you go.

Limited understanding of quantum mechanics so feel free to correct me.

>>972892
LMAO, you want to know why different scales behave differntly. Its called statistics, do you know it?

>>972918
Here, wiki had this handy chart. It's a reasonable interpretation.

>>972928
This chart doesnt account for gravity. All of that stuff is makes sense "without gravity". Gravity fucks everything up.

>>972935

Explain, because it's the first time I heard anything about relativistic functions being screwed over by gravity.

>>972915
torsion physics hurt my head

QM governs the very small
Relativity the very large
Newton's laws the inbetween stuff like us.

It's pretty easy to work the math from Newton to relativity (I said pretty easy) but the quantum world is just too different to say it obeys the same laws.

If you can create a unified field theory I will suck your dick dry.

>>972975
>Relativity the very large

NO NO NO, ENGINEERING FAG!
JUST STFU!
you have no idea what the fuck you are talking about. SR applies to QM systems. Dirac equation anyone?

>>972989
engineer who loves the dirac function reporting :D

>>972989
I read that as dire equations and developed a fear of mathbooks

>>972935
So, that chart work for everything but the force of gravity pretty much. There is no Quantum Gravity theory. The standard model doesnt include gravity.

OK, everyone keeps telling me things work differently on a large scale and small scale, but noone has said why. Big and small don't behave differently "just coz"

>>972916
Sorry, I missed this one. So basically we know that it happens, but have yet to come up with a valid reason?

>>973008
Ok, sorry...lol

>>972975
Don't mind me, I'm trivial
<div class="math">{R^\tau}_{\alpha\gamma\beta} = \partial_\gamma \Gamma^\tau_{\beta\alpha}-\partial_\beta \Gamma^\tau_{\gamma\alpha} + \Gamma^\tau_{\gamma\mu} \Gamma^\mu_{\beta\alpha}-\Gamma^\tau_{\beta\mu}\Gamma^\mu_{\gamma\alpha}</div>
<div class="math">\Gamma^\tau_{\beta\alpha} = \frac{1}{2} g^{\alpha\tau}\left(\frac{\partial g_{\alpha_mu}}{\partial u^\beta}+\frac{\partial g_{\beta\alpha}}{\partial u^\mu}+\frac{\partial g_{\mu\beta}}{\partial u^\alpha}\right)</div>

>>973014
YOUR FUCKING RETARDED! I ALREADY TOLD YOU...ITS STATISTICS!

You can extrapolate classical physics "middle" scale, from statictics and QFT "smaller" scale.
Like wise a GR will eventaully be able to be extraploated from a Quantum gravity using statistics.

STATS BITCH!

>>973021
>Sorry, I missed this one. So basically we know that it happens, but have yet to come up with a valid reason?
Correct. But that's true of just about every phenomenon in existence, so I'd counsel you to stop asking the "why" question. Think about it: we KNOW that an apple dropped from a height on the Earth will accelerate at 9.8 m/s/s. But why? Even to that simple question, we have no firm answer. "Because of gravity" is not a sufficient response. We have competing theories about what gravity is. In fact, we do not know what causes gravity--is it a boson like the other forces? Is it from the curvature of spacetime as Einstein suggested? Quantum fields? Open strings?

"Why" simply isn't a very good or productive question.

>>973046
Thank you. What about this response:
>>973042

>>972838
OP you sound like an dumbass engineer?

>>973042
Jeez, calm down. That's not really an explanation for him, you know.

>>973014
Effectively, what the angry loud man is trying to say is that one of the outcomes of QM (and, by the way, this is STILL contested) is the idea that interactions among particles are not deterministic--there is an element of chance in the way they behave. Many interpretations of QM view Schroedinger's wave as a probability distribution describing possible and likely states of a particle's momentum and position.

Thus, classical mechanics can be "derived" from QM at the appropriate scales by running the numbers--for large populations of particles (i.e. 10^23), the numbers kind of average out, leaving you with nice, predictable trajectories.