particles backward in time?

Question

at QED Feynman's book he claims that anti-particles can be seen as matter traveling backward in time.
Can anyone help me picture this? Can it be a simple movement and the time-dimension be "felt" as normal?

there is a similar post with the question "Anyone of you ever hear a theory that anti-particles are merely ordinary matter traveling backward in time?" but there isn´t really an answer there

Answer 1

This was not proposed as a "theory", which is, by definition testable, but an "interpretation" of the CPT invariance of quantum mechanics. An interpretation in physics is just a way of looking at things *consistent with* a theory, but formally extraneous to it. It does not violate relativity since the *magnitude* of the velocity is less than c. There's no prohibition in relativity for either particles or automobiles to move in reverse. CPT invariance means if you simultaneously reverse a set of particles' charge (turn them into their respective antiparticles), Parity (take their mirror image), and Time evolution (direction of motion), they behave exactly the same way amongst each other.

It gets better. One version of the interpretation is that, not only is a, say, positron, just an electron traveling backwards in time, but it is the *same* electron. Indeed, there is only one electron in the entire universe busily traveling forwards and backwards in time to fill space with its myriad traverses. Everytime you see an electron-positron pair creation or annihilation, that's just the electron hitting a gamma ray, causing both (gammas are their own antiparticle) to reverse course. Presumably, most positrons return in a distant part of the universe. The same is true of other particles, of course. One virtue of this interpretation is that it "explains" why all particles of a given type are identical (because they're the same one).

Quantum Mechanics has all sorts of wacky interpretations associated with it. This is not the wierdest. Google "Schrodinger's Cat" or "Dirac sea" or "many worlds interpretation". QM is just an all around wacky theory. Richard Feynman said, "Anyone who thinks they understand quantum mechanics doesn't understand quantum mechanics"

Answer 2

Hello. I know you have read this info from a book, but such a thing isnt possible. The time-space continuum isnt perceived properly. There is no way to disrupt the fabric of time, and as far as i can tell, there never will be. Even if an anomaly of sufficient size was found the "fabric" of time cant be interfered with. Think of it this way: Time is just a way of telling when an event happened. Can you "capture 12:00? no. Its not possible.

Answer 3

He doesn't mean that anti-particles literally move back in time. He just means that for conceptual purposes, it's as if they do.

Let me make an analogy. When electricity flows through a wire, electrons are moving. Electrons have a negative charge. But for the purposes of calculations, we pretend that positive charges are moving in the opposite direction. Current is defined as the apparent flow of positive charges, because a negative charge flowing in one direction is, for all practical purposes, the same as a positive charge flowing in the opposite direction.

You have to understand that a lot of science works on models. Models are merely representations which allow us to make accurate predictions and account for the evidence. They don't necessarily represent concrete reality. They are just useful tools.

Answer 4

I'm having trouble with this. This seems completely contrary to Einstein's theory of relativity. Which means in your scenario that the matter would be traveling at the speed of light or faster. I don't think that's right. Maybe Hawking can help!

Answer 5

i'm undecided it truly is hypothetical. Tachyons are subatomic debris that shuttle speedier than mild and so might certainly bypass backwards in time. i do no longer see how this impacts on the existence of G-d, nevertheless. Zvi the Fiddler

Answer 6

I became fascinated with this as a junior high kid. I wanted to figure out a way to send a message back in time with positrons.
Quite disappointing to hear that like post above it is thought to be 'as if' they are moving back in time but not actually. It works out mathematically. But if you do manage to make a morse code signal back to the past let me know. :-)

Answer 7

can't, the particle would freeze in time if it went faster than light.

Answer 8

no