Need Physics Help with Double Slit Experiment

[monitoradiation]

The thread by ChattieSpike made me recall something I'd wanted to ask some physicists.

The Feynman formuation of quantum mechanics suggests that in the famous double-slit experiment, the electron travels through ALL possible trajectories through both slits (ie an infinity of trajectories).

The problem I have is this:

If there are an infinity of trajectories that the particle travels through, and we understand that the maximum speed allowed is the speed of light (even for gravitational influence) how does this mesh?

I understand that it could be a sort of "potentialities" argument that the electron doesn't actualy go through ALL of them but merely chooses the most probable one according to its wavefunction and how the experiment is set up, but in order for the information of an INFINITE number of trajectories for the electron to decide upon (if you can call it that), wouldn't it necessarily take forever for the information to be gathered since we've established that information transfer cannot be instantaneous?

 

[JustBusiness17]

The thread by ChattieSpike made me recall something I'd wanted to ask some physicists.

The Feynman formuation of quantum mechanics suggests that in the famous double-slit experiment, the electron travels through ALL possible trajectories through both slits (ie an infinity of trajectories).

The problem I have is this:

If there are an infinity of trajectories that the particle travels through, and we understand that the maximum speed allowed is the speed of light (even for gravitational influence) how does this mesh?

I understand that it could be a sort of "potentialities" argument that the electron doesn't actualy go through ALL of them but merely chooses the most probable one according to its wavefunction and how the experiment is set up, but in order for the information of an INFINITE number of trajectories for the electron to decide upon (if you can call it that), wouldn't it necessarily take forever for the information to be gathered since we've established that information transfer cannot be instantaneous?

As I understand it, this quagmire is the basis for the idea that we may just be one of infinity universes. The electron does take all routes, but it can only take one route in our version of reality... Every other route corresponds to a new reality.

It's fucked, I know :lol:

 

[Master_Ghost_Knight]

Not quite because it goes trough both sliths in our reality and that is why we see an interfeernce patern and not a random splater.

 

[JustBusiness17]

Not quite because it goes trough both sliths in our reality and that is why we see an interfeernce patern and not a random splater.

Oh yeah... I forgot about interference patterns...

They talk about it in this documentary:

 

[monitoradiation]

I think the major point is being missed...

I was talking about the Feynman formulation of quantum mechanics that explains HOW the electrons travel through both slits, not the result of them doing so. He describes them as travelling infinite numbers of possible trajectories and then at the end somehow "deciding" on one. My question is if there are infinite numbers of possible trajectories how can an electron actually travel on all of them simultaneously, and if in fact its NOT travelling through all possible trajectories but merely choosing from potential trajectories, how it gets its information since some trajectories will go to the billions of light years away and back.

 

[JustBusiness17]

I think the major point is being missed...

I was talking about the Feynman formulation of quantum mechanics that explains HOW the electrons travel through both slits, not the result of them doing so. He describes them as travelling infinite numbers of possible trajectories and then at the end somehow "deciding" on one. My question is if there are infinite numbers of possible trajectories how can an electron actually travel on all of them simultaneously, and if in fact its NOT travelling through all possible trajectories but merely choosing from potential trajectories, how it gets its information since some trajectories will go to the billions of light years away and back.

I don't think there's a simple answer to your question. As far as I'm aware, you're inquiring about things that really haven't been answered yet. There seems to be a lot of speculation regarding the subject, but unfortunately, observation is restricted to our own reality. It seems like the only thing we know is that an electron can take any of it's possible trajectories, but in our reality, it only takes one.

Watch the documentary I posted and hopefully it will answer some of your questions or help you to formulate more answerable questions.

Of course, I'm not a physicist so I could be talking out of my ass...

 

[Nelson]

I think you are talking about Feynman path integrals. This is simply a mathematical formulation of quantum mechanics used to calculate probabilities, and it does not necessarily say that the particles does travel through all possible trajectories or even gain information from all of them. The path-integral formulation has been shown to be a good model by empirical testing. One can make predictions about events on the quantum scale using this formulation, and experiments have shown them to be accurate. The point I'm trying to make here is the difference between the mathematics we use to model reality, and reality itself. This source suggests that Feynman was instead in favor of the many worlds interpretation:

http://www.hedweb.com/everett/everett.htm#believes

"Political scientist" L David Raub reports a poll of 72 of the "leading cosmologists and other quantum field theorists" about the "Many-Worlds Interpretation" and gives the following response breakdown [T].


1) "Yes, I think MWI is true" 58%
2) "No, I don't accept MWI" 18%
3) "Maybe it's true but I'm not yet convinced" 13%
4) "I have no opinion one way or the other" 11%

Amongst the "Yes, I think MWI is true" crowd listed are Stephen Hawking and Nobel Laureates Murray Gell-Mann and Richard Feynman. Gell-Mann and Hawking recorded reservations with the name "many-worlds", but not with the theory's content. Nobel Laureate Steven Weinberg is also mentioned as a many-worlder, although the suggestion is not when the poll was conducted, presumably before 1988 (when Feynman died). The only "No, I don't accept MWI" named is Penrose.

In this case, the particle only takes one path per universe, but there are an infinite number of universes, and it takes a different trajectory in each one.

 

[monitoradiation]

The point I'm trying to make here is the difference between the mathematics we use to model reality, and reality itself.

Hmm. I guess that makes some sense. It's just that the implication of integrating over all possible paths sounded as if it's something the electron would "know" as well. Thanks for your response.

 

[Nelson]

Hmm. I guess that makes some sense. It's just that the implication of integrating over all possible paths sounded as if it's something the electron would "know" as well. Thanks for your response.

Well, the next logical question is "Why does this formulation work if it doesn't ACTUALLY mean that the particle is traveling through all possible trajectories?" And the answer is: I have no clue. I just wanted to point out that while Feynman was a strong advocate of the path integral formulation for it's utility, he didn't necessarily believe that interpretation. I think your question is still quite valid, it just isn't a position that Feynman would have argued for.

 

[monitoradiation]

Well, the next logical question is "Why does this formulation work if it doesn't ACTUALLY mean that the particle is traveling through all possible trajectories?" And the answer is: I have no clue. I just wanted to point out that while Feynman was a strong advocate of the path integral formulation for it's utility, he didn't necessarily believe that interpretation. I think your question is still quite valid, it just isn't a position that Feynman would have argued for.

Well, I thought about it a little more; integration is actually addition of infinitessimals to a limit; and, as in all limits to infinity (for example, say of G = lim _x-> inf 1/x), it's not as if it is possible to enumerate every number between 0 and inf for x. You merely express it as a limit as a number approaches a particular goal and you express G = lim_x-> inf 1/x = 0.

I'm still sorta unconvinced by this reasoning, but I think it's reasonable enough for me to accept that tentatively...

 

[Predanator]

The classical electron corresponds to the collapsed wave function. The uncollapsed wave function that exists between the the electron source and the screen doesn't correspond to that localized point particle. The uncollapsed wave function traverses both slits resulting in the diffraction pattern being part of the wave function post-slit. When that diffracty wave function collapses upon interacting with the screen, then the election resumes its more classical nature.

There is no infinite universe theory as part of QM.