Double slit and time dilation

[Dord]

Hello everybody.

Here is my entry for dumbest question of the day, and I assume replies will include most of the Greek alphabet and squiggly lines that I won't understand but here goes anyway...

Q:  Do particles experience gravitational time dilation?

If I've got this right, gravitational time dilation occurs when two synchronised "clocks" are seperated and exposed to different levels of gravitational force resulting with thier times being no longer synchronised.

And if I've also got this right, particles etc can occupy two places at once - as in the double slit experiment where a single photon passes through both slits at once.

So... if there is a way to make each slit experience a significant difference in gravitational force* would this have any affect on the two "parts" of the photon which are both travelling at c but one seemingly slower than the other?

Thanks, and my apologies for any incorrect terminology or assumptions.

(*I assume that they do anyway but on a very, very small scale.)

[swansont]

40 minutes ago, Dord said:

Hello everybody.

Here is my entry for dumbest question of the day, and I assume replies will include most of the Greek alphabet and squiggly lines that I won't understand but here goes anyway...

Q:  Do particles experience gravitational time dilation?

Yes. The atoms in an atomic clock, for example, explicitly experience the effect.

 

40 minutes ago, Dord said:

If I've got this right, gravitational time dilation occurs when two synchronised "clocks" are seperated and exposed to different levels of gravitational force resulting with thier times being no longer synchronised.

And if I've also got this right, particles etc can occupy two places at once - as in the double slit experiment where a single photon passes through both slits at once.

So... if there is a way to make each slit experience a significant difference in gravitational force* would this have any affect on the two "parts" of the photon which are both travelling at c but one seemingly slower than the other?

Thanks, and my apologies for any incorrect terminology or assumptions.

(*I assume that they do anyway but on a very, very small scale.)

It’s not specifically the gravitational force that results in time dilation, it’s the potential - the position in the gravitational field. So a constant g would still result in time dilation for different vertical positions.

If your slits were spaced vertically, there would be an effect. Or if you tossed atoms in a superposition, where the two states would go to different heights. Mark Kasevich has done such experiments with his 10m tower.

[Dord]

Thank you @swansont 

10 minutes ago, swansont said:

Mark Kasevich has done such experiments with his 10m tower.

I've found this online:

https://web.stanford.edu/group/kasevich/cgi-bin/wordpress/?page_id=11

It looks very interesting, and seems a natural progression from Galileo dropping his balls to the famous photo- op on the moon.

[Dord]

On 5/28/2020 at 6:18 PM, swansont said:

If your slits were spaced vertically, there would be an effect.

What I don't understand is what that effect would be for a single photon.

I get that a single photon sent through a double-slit passes through both slits at the same time, before continuing to a screen where it displays an interference pattern.  I also get that a vertical double-slit creates time dilation due to gravitational potential.

This is where I am struggling: 

My intial thought was that the two "parts" of the photon would arrive at the screen at different times because one was travelling slower than the other due to gravitational time dilation.  But this cannot be right as they are both travelling at c.  (This thought was based on the fact that two synchronised atomic clocks seperated vertically will display different times due gravitational time dilation.)

I then thought that it might be something to do with frames of reference that is beyond me for now.

Thanks for reading.
 

Edited June 2, 2020 by Dord

[swansont]

11 minutes ago, Dord said:

What I don't understand is what that effect would be for a single photon.

I get that a single photon sent through a double-slit passes through both slits at the same time, before continuing to a screen where it displays an interference pattern.  I also get that a vertical double-slit creates time dilation due to gravitational potential.

This is where I am struggling: 

My intial thought was that the two "parts" of the photon would arrive at the screen at different times because one was travelling slower than the other due to gravitational time dilation.  But this cannot be right as they are both travelling at c.  (This thought was based on the fact that two synchronised atomic clocks seperated vertically will display different times due gravitational time dilation.)

I then thought that it might be something to do with frames of reference that is beyond me for now.

Thanks for reading.
 

Gravity would change the energy of the photon. That would show up as a difference in phase. If you rotated from vertical to horizontal you would expect a fringe shift.

[Dord]

With the grateful help from numerous forum contributors, I have now realised that my visualisation of photons and the double-slit experiment was fundamentally flawed.

I wanted to explore what effects gravity may have on c when a photon is 'split' but as it doesn't do that I have failed miserably. I shall, possibly, reconsider what I'm trying to ask with a more sensible question in the future.

In the meantime, and to prevent myself from further embarrassment, am I correct in thinking that a photon is not a particle and a wave; it is represented as either one or the other?

Also, the commonly used picture of a wave - akin to numerous ripples going across a pool of still water - confused me initially. To me, it looks like many 'waves' pulsing across the page but am I right in thinking that it may be better described as the same wave drawn at different points in time?

In my minds eye, I am now picturing a wave as an expanding balloon or an explosion's shock wave with just a single 'edge' that grows progressively larger in all directions.  Does this sound like a helpful image for a layman to use?

Thanks for your time.

[Markus Hanke]

On 5/28/2020 at 6:51 PM, Dord said:

Galileo dropping his balls

Sorry, but...I had to laugh at this 😄