Anti-hydrogen beam?

  • #1
LightningInAJar
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Anti-hydrogen beam??
Did anyone ever create a beam of anti-hydrogen to see if antimatter reverses the direction of time?
 
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  • #2
weirdoguy
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to see if antimatter reverses the direction of time?

Why would it? And what does that even mean? I think I know where you got this idea from, but let's see if you understood what you read.
 
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  • #3
Vanadium 50
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I have no idea where he got the idea from, and hope he can explain what "reverses the direction of time" means and more importantly, what measurement could be performed that would tell you you've done that.
 
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  • #4
vanhees71
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Indeed there are investigations on antihydrogen, e.g., at CERN. The most recent news I know of is that the spectrum looks as expected the same as for usual hydrogen.

https://www.nature.com/articles/s41586-020-2006-5 (open access!)

Why it should reverse the direction of time, is an enigma to me. Nobody ever claimed that antimatter reverses the direction of time in any way. If you are referring to the "Feynman-Stueckelberg trick" this is not "particles moving backwards in time", as is often claimed in popular-science writing, but it's simply to put a creation operator instead of an annihilation operator in the mode decomposition of the (free-)field operators in order to get a local realization of the proper orthochronous Poincare group without violating the demand to have a Hamiltonian bounded from below (after proper choice of the vacuum energy to be 0 a positive definite Hamiltonian).
 
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  • #5
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Beams of antiprotons have been used routinely for decades. The Tevatron for example collided protons and antiprotons.

In the calculations antiparticles have some similarity to particles if you exchange the time direction in the calculations (that's the laypeople-friendly explanation of what vanhees wrote), but that doesn't make anything go backwards in time.
An object thrown up has a mathematical similarity to an object falling down with reversed time direction, but that doesn't mean a ball starts time traveling if you throw it upwards.
 
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vanhees71
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Well, as far as I know, the anti-matter-free-fall experiment hasn't been done yet, but I'm pretty sure it will come out what's predicted by GR (or Newtonian gravity for that matter): antiparticles are attracted as particles through the gravitational interaction.
 
  • #7
Vanadium 50
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Can we please wait for the OP to clarify? I know "Guess what he means" is a popular PF game, but...
 
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  • #8
LightningInAJar
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Feel free to guess. I like the answers I'm getting. Maybe the presents of antimatter can slow the forward passage of time? Someone told me that we simply can't produce enough of it to get a noticeable difference?
 
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  • #9
Vanadium 50
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Feel free to guess.

I'm sorry, I mistook you for someone who wanted a serious conversation.

Maybe the presents of antimatter can slow the forward passage of time?

The presents? Are they wrapped with bows on them?
 
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  • #10
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if antimatter reverses the direction of time?
Feel free to guess.
Maybe the presents of antimatter can slow the forward passage of time? Someone told me that we simply can't produce enough of it to get a noticeable difference?

All of these are signs that this thread needs to be closed for being way too speculative and vague, not to mention based on a misconception from the start. I have heeded the signs.
 
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