I'm interested in the extent to which quantum physical effects are seen at a macroscopic level. I might get some of the physics wrong, but I think I'll get it close enough that I can ask the question:

Let's sat that we create a bonfire and let it burn until it burns out. As the smoke rises from the fire, turbulence takes over and the smoke particles and steam and hot air all mixed together. By the end of the night when the fire has burned out, the collection of molecules in the system are in some position/velocity X.

My question: Let's assume the multiverse interpretation of quantum physics. How many possible end state superpositions can there be in this situation? Ok, that's imprecise and incorrect because it would actually be an uncountable infinitude of possible end states. How about this: Given the end state that we observed, what percentage of the end state superposition would be "visually" indiscernable from the end state that we observed so that each molecule would be in nearly the same end state across that portion of the multiverse?

Or put another way: Do quantum effects sneak into everyday life fast enough that we can observe them? If we are effected by quantum physics at all, I imagine this is roughly a function of the timescale of the chaos effects.

Schwarzschild singularities are described by the Kantowski-Sachs metric with a contracting S². Of course, T-duality doesn't apply to S². But what about a Kasner-type singularity with two contracting spatial dimensions compactified over a torus T², and an expanding spatial dimension? The T-dual of the torus gives rise to a geometry which is expanding in all spatial directions

There is no tunneling in the case of infinite potential barrier, but there is when we have a finite well. In the classical analog, in the first case we have a particle bouncing between to infinitely rigid impenetrable walls and there is no tunneling, same as the quantum case. But if we have a finite barrier, means we have walls of finite rigidity, say made of cork or something. Then the particle would just break through some of the cork and it's probability of being found further in the cork wall will decay steadily.

I can understand discrete energy levels being a new thing, because they behave like a wave that's confined and not like particles confined, but why tunneling?

Who hasn't heard about the double-slit experiment? It figures in any book of quantum physics. But there is something no one can explain to me : I understand why the light cannot be described only as a wave, but I do not understand why it cannot be explained only in terms of a particle, having some trajectory, following other laws of phyisics we may not know. Usually, every book in which I have tried to look for an answer considers that if it cannot be described as a classical trajectory (which is clearly the case in this experiment), then it is not a particle, that is, a material point. Could it not be a particle following new laws?

By what mechanism do quantum effects become observable in normal life at the macroscopic level? For instance, when two molecules "collide" is the momentum a probabilistic event wherein the end state is not unique? Another example, during a chemical reaction, it is a probabilistic event at the quantum level whether or not any particular molecule within the solution interacts with another molecule?

Why is there a consistent theory of continuum mechanics in which one just consider things like differential elements and apply Newtons laws? Is there a deeper reason for it. Is it the nature of newtonian framework that makes it happen or is it somehow related to nature of bodies (topological spaces with borel measure etc)?

I've been looking for questions about dark matter, and I've read some very interesting answers. However, I desire too look into it deeply.

This is not actually a question. I'm asking the community to recommend interesting references to understanding dark matter and dark energy.

I accept all sort of references: notes, books, scientific papers etc.

Let us assume some background on classical physics, thermodynamics and basics about quantum theory.

Ilya and Anya each can run at a speed of 8.80mph and walk at a speed of 3.70mph . They set off together on a route of length 5.00 miles. Anya walks half of the distance and runs the other half, while Ilya walks half of the time and runs the other half.

A. How long does it take Anya to cover the distance of 5.00 miles? Express your answer numerically, in minutes.

B. Find Anya's average speed. Express Anya's average speed numerically, in miles per hour.

C. How long does it take Ilya to cover the distance? Express the time taken by Ilya numerically, in minutes.

D. Now find Ilya's average speed. Express Ilya's average speed numerically, in miles per hour.

The solar neutrino problem has been "solved" by discovering that neutrinos have mass and they oscillate. So how accurate are now our predictions about the number and types of solar neutrinos that reach the earth?

It is well accepted that quantum theory has well adapted itself to the requirements of special relativity. Quantum field theories are perfect examples of this peaceful coexistence. However I sometimes tend to feel little uneasy about some aspects. Consider an EPR pair of particles light years apart. Suppose there are 2 observers moving relative to each other with constant relative velocity. Let us consider, there are spin detection mechanism at both end for each particle. Now suppose one of the observer is at rest w.r.t. the detector for the first particle. As soon as the detection made, the wave function of the 2 particle entangled system will collapse instantaneously and the second particle must realize a definite opposite spin value. Now due to relativity of simultaneity, the second observer may claim that the collapse of the wave function for the two particle system is not simultaneous. He may even claim that the second particle is measured first. In that case a special frame of reference will be privileged, the frame at which the wave function collapsed instantaneously. This will cause a significant strain on the core principle of special relativity.

I am sure the above reasoning is flawed. My question is where?

In all examples that I know, tachyons are described by scalar fields. I was wondering why you can't have a tachyon with spin 1. If this spinning tachyon were to condense to a vacuum, the vacuum wouldn't be Lorentz invariant---seems exotic but not a-priori inconsistent. Is there some stronger consistency requirement which rules out spinning tachyons? If someone could provide a reference that would be helpful too!

Here's another confusion: I was reading Wikipedia, which claims that tachyons should be spinless and obey Fermi-Dirac statistics(?). (They reference an original paper by G. Feinberg which unfortunately I am not wealthy enough to download). The claim about Fermi-Dirac statistics is baffling---isn't the Higgs field a boson? Does anyone understand what they're talking about?

I'm begining to study Quantization of field with the second quantization formalism. I've studied phononic field, electromagnetic field in the vacuum and a generic relativistical scalar field.

I asked to me if is possible doing the same thing with the Gravitational Field Hamiltonian.

I've heard that we can do it only in the condition of linearized Gravity and we obtain a field with spin 2, but we can't do it in the general condition because we don't have quantization conditions.

What are these conditions? And how can we obtain only in linearized gravity the quantized field? And how it has got spin 2?

This question has its origin to the reference on the Aegis experiment at CERN where they aim to produce super cooled antihydrogen and detect whether its reaction to gravity is negative.

It set me thinking that the beams in the Tevatron circulate for more than a second and everything falls about 4.9 meters in a second, so the bunches must be falling too. This of course will be compensated by the fields that keep the bunches in track among all the other corrections necessary. If though the antiprotons have a different behavior under gravity, this difference would appear in the orbits of protons and antiprotons.

The question has two points: a) since the beams are travelling equal and opposite paths through the magnetic circuit, a negative gravity effect on antiprotons would disperse the antiproton beam up with respect to the path of the proton one. Could one get a limit on the magnitude of the gravitational effect difference between protons and antiprotons from this?

I found one reference where the antiproton beam has a different behavior in chromaticity than the proton one, and it is explained away.

Now I am completely vague about beam dynamics which I have filed under "art" rather than "physics" but b) am wondering whether this observed difference could be interpreted as a gravitational field difference in a dedicated experiment.

Maybe there are beam engineers reading this list. My feeling is that if antiparticles had negative gravity interactions , beam engineers would have detected it since the first e+e- machine, but feelings can be wrong.

How do you effectively study physics? How does one read a physics book instead or just staring at it for hours?

(Apologies in advance if the question is ill-posed or too subjective in its current form to meet the requirements of the FAQ; I'd certainly appreciate any suggestions for its modification if need be.)

Assume an observer sent a beam of photons close to an event horizon, say at some distance x (a distance far enough to avoid the photons falling in.) This light would still be observable, albeit red shifted and with it's path curved appropriately. Now assume the black hole absorbs enough mass to expand it's event horizon beyond the distance x. This stream of photons would stop. Does the observer not have information about a process that occurred exactly at the event horizon, that is it's expansion? Isn't this a region that one should not be able to get any information about due to the fact that nothing could contact the event horizon and return to the observer?