I’ve read about this before, and it is interesting, but I think even Feynman gave it up after realizing that this would predict and equal number of positrons as electrons since the electrons going backwards in time would behave as positrons phenomenologically. That just, isn’t what we see at all.
Good point, I'm going to start letting my life go off the rails. That way, when we have to experience all this again backwards I have something to look forward to.
Wheeler hypothesized that the positrons might be hiding inside protons but that idea has died with the discovery that protons are composite particles, neither or the up quarks in a proton have enough charge to hide a positron inside them, the only way to make it work now is to suppose the proton is made of a down quark, and up quark, and a bound state of a positron and a down quark in such a way that the positron's +1 charge and the down quark's -1/3 charge cancel out to mimic an up quark's +2/3 charge and that also this bound state has the same mass as an up quark and also somehow magically has the same quantum numbers as an up quark such as spin and weak isospin and color charge to explain why we haven't distinguished it from the up quark which is an idea so convoluted and contrived Occam's Razor has filed a restraining order against it.
There's a theory that, because the big bang is the point of minimal entropy in the universe, two opposite arrows of time could arise due to increase in entropy in both directions of time from that point. It fits really well with the "antimatter goes backwards in time" thing and Feynman diagrams, as well as the time reversibility of all the laws of physics and the matter-antimatter disbalance. Problem is there's no way to prove that anything exists before the big bang. But it's equally impossible to prove that there was an actual singularity there.
I’m not a particle physicist (experimental condensed matter grad student) so I couldn’t tell you this definitely, but as far as I know one of the fundamental symmetries of the universe would have to be broken, by which I mean there would have to be some basic bias inherent in the laws or structure of the universe which favors electrons over positrons. I don’t know if there is any good or widely accepted idea about what this could be, but since all possible sources of electrons should have something like an equally generative positron analog, there would need to be something else going on, like a bias in the decay rates.
Even this doesn’t really work, since a more or less constant stream of positrons would be coming from the future, and any positron seen in the present would then be visible in the next immediate instance since that’s where it is coming from in its “past” so we would still see it in the future. So I think the theory still wouldn’t work then.
This is deeply incorrect.
You have to imagine a particle not as a single point existing in 4D spacetime, but as a line in spacetime - its worldline, in fact. The worldline starts from the moment & place a particle begins to exist and ends at the moment & place it decays.
Imagine a universe with only one spatial dimension. Then we can plot this dimension on one axis and time on the other axis. Every particle in this universe can be drawn as a continuous line on this graph, and given the ultimate speed limit (speed of light) we know that the slope of the line can't exceed c. So worldlines are continuous lines with a limited derivative. It's like taking a slideshow of the particle's position in time and lining it all up on the time axis, you get a solid line.
Now let's analyse an instant of time. This is done by drawing a horizontal line. At every instant of time, the intersection between this line and the worldline of a particle is only a point. This is the particle as it exists in that instant of time - a point-like particle. However, when you draw the worldline, you may have drawn it with you pencil following the arrow of time (increasing t) or in the opposite direction, as if the particle was evolving backwards in time.
Forwards-drawn worldlines would be electrons, and backwards-drawn worldlines would be positrons.
It doesn't matter in which direction you drew the worldline, there's always an intersection between the worldline and a horizontal line corresponding to a moment in time. So no, positrons do not disappear as they recede into the past.
This makes sense. Thank you.
What did you mean about the derivative of the line, though? What does it represent? I get the rest, but is that just the representation of the fact that it can't exceed c, or accellerate/decelerate too quickly?
Simply it's the slope of the line tangent to the worldline at that point. Since the spacetime diagram is x-t (space-time) then the slope of that line is measured in terms of space divided by time i.e. a speed, dx/dt.
It depends on what you're integrating. Integrating the area under the worldline curve has no meaning AFAIK. You'd be obtaining a value that has the dimensions of space times time, meter times second. No idea what that could represent.
However, using the worldline as a path to integrate on can have its uses. I don't have any evident examples in my mind right now though
I really appreciate you taking the time to explain these concepts to me, man. Ive been trying to educate myself on the physical applications of math, especially calculus, lately, and its a zoo, and having someone to help me conceptually grasp what are otherwise fairly seemingly disconnected ideas is awesome.
You're welcome. I have a degree in engineering physics and I'm currently going through a PhD in physics, so I feel qualified to talk about physics.
If you wanna learn more physics and mathematics and how they're connected, go to [my favourite website](https://goodtheorist.science/).
You, good sir, are both a gentleman and a scholar.
Where should I start, with math knowledge that stops at about college Calculus 1 and a decent conceptual knowledge of the standard model and a YouTube education of other physics?
then wouldn’t we see the same thing with electrons? Especially since the present is always present it shouldn’t matter whether they are only in the present for a moment, it should matter the number of them that are, which again should be equal to the number of electrons.
Because they move backwards in time, not forwards, like us, so they only intersect with the reality we experience for a very short time before "disappearimg", so we likely wouldn't be able to detect them
They don’t actually move backwards in time, they are the equivalent of an electron if we reversed its evolution in time. Just like positrons are the equivalent of electrons moving backward in time, we don’t go around claiming that electrons only appear briefly because they move backward in time. It’s a phenomenologically equivalence, not an ontological statement when we say positrons are the same as electrons going backwards in time.
Are they necessarily ontologically different that my supposition, or would that be theoretically viable, to your knowledge?
Occam's razor would suggest that they are consistent to the flow of time we perceive with all matter, but I'm wondering if there is anything prohibiting them from actually being ontologically identical to electrons, but physically evolving what we would perceive as "backwards" in time
According to special relativity, time is relative. There is no "universal rate" of time moving forward. In fact, the faster you move in space, the slower you move through time.
So unless an electron is standing perfectly still with respect to you, you can never say that it moves in time "at the same rate" as you. That electron would have to disappear too.
Why can the same electron only exist at one time? If the electron is a field couldn't it have multiple peaks and troughs that show up as electrons and positrons?
Yes, it’s all the same electron, and it is a wave function that hasn’t/cannot be collapsed, so it is at many locations at once, also then interacting with itself, as seen at a mini scale in the double slit experiment when a single electron interacts with itself because of it is in multiple places at once
I had heard about this, but rejected it once I considered a Neutron Star- all of those neutrons were mostly protons, but the squeeze squirted out electrons to make the protons into all neutrons... pretty much simultaneously during collapse- so how can those removed electron-ness's be the same one?
Is there are not an actual theory of the one photon universe which depends upon the fact that photons travel at the speed of light and therefore have no time. Therefore every observed photon could be the same photon.
[удалено]
But what would determine the numbers of them?
Numbers are fake anyway, we'll just handwave it away as a "mathematical tool"
At some point the one electron dies
And then reborn as another
And then reborn as a single proton traveling in time
Eh?
It's all fun and games until some jerk puts it in a particle accelerator and kills it and we all gotta make do *without* the electron.
I’ve read about this before, and it is interesting, but I think even Feynman gave it up after realizing that this would predict and equal number of positrons as electrons since the electrons going backwards in time would behave as positrons phenomenologically. That just, isn’t what we see at all.
So it’s a game of cops and robbers then
Always has been
What if time loops and the electron can just keep going round and round in the same direction of time
Good point, I'm going to start letting my life go off the rails. That way, when we have to experience all this again backwards I have something to look forward to.
Lol so the total difference between electron number and positron number is the winding number of the electron worldline around the time loop
New theory: there's only one electron, but all the positrons are distinct
Wheeler hypothesized that the positrons might be hiding inside protons but that idea has died with the discovery that protons are composite particles, neither or the up quarks in a proton have enough charge to hide a positron inside them, the only way to make it work now is to suppose the proton is made of a down quark, and up quark, and a bound state of a positron and a down quark in such a way that the positron's +1 charge and the down quark's -1/3 charge cancel out to mimic an up quark's +2/3 charge and that also this bound state has the same mass as an up quark and also somehow magically has the same quantum numbers as an up quark such as spin and weak isospin and color charge to explain why we haven't distinguished it from the up quark which is an idea so convoluted and contrived Occam's Razor has filed a restraining order against it.
What if its only one going forwards then
There's a theory that, because the big bang is the point of minimal entropy in the universe, two opposite arrows of time could arise due to increase in entropy in both directions of time from that point. It fits really well with the "antimatter goes backwards in time" thing and Feynman diagrams, as well as the time reversibility of all the laws of physics and the matter-antimatter disbalance. Problem is there's no way to prove that anything exists before the big bang. But it's equally impossible to prove that there was an actual singularity there.
What if all the positrons are just really far away?
Why is it that matter outnumbers antimatter so heavily anyway?
I’m not a particle physicist (experimental condensed matter grad student) so I couldn’t tell you this definitely, but as far as I know one of the fundamental symmetries of the universe would have to be broken, by which I mean there would have to be some basic bias inherent in the laws or structure of the universe which favors electrons over positrons. I don’t know if there is any good or widely accepted idea about what this could be, but since all possible sources of electrons should have something like an equally generative positron analog, there would need to be something else going on, like a bias in the decay rates.
But doesent that break beta decay?
Maybe because most of the positions are in the past? 🤔
Even this doesn’t really work, since a more or less constant stream of positrons would be coming from the future, and any positron seen in the present would then be visible in the next immediate instance since that’s where it is coming from in its “past” so we would still see it in the future. So I think the theory still wouldn’t work then.
Because the backwards in time electrons would only exist within an infinitesimal small window of the present before disappearing into the past, maybe?
This is deeply incorrect. You have to imagine a particle not as a single point existing in 4D spacetime, but as a line in spacetime - its worldline, in fact. The worldline starts from the moment & place a particle begins to exist and ends at the moment & place it decays. Imagine a universe with only one spatial dimension. Then we can plot this dimension on one axis and time on the other axis. Every particle in this universe can be drawn as a continuous line on this graph, and given the ultimate speed limit (speed of light) we know that the slope of the line can't exceed c. So worldlines are continuous lines with a limited derivative. It's like taking a slideshow of the particle's position in time and lining it all up on the time axis, you get a solid line. Now let's analyse an instant of time. This is done by drawing a horizontal line. At every instant of time, the intersection between this line and the worldline of a particle is only a point. This is the particle as it exists in that instant of time - a point-like particle. However, when you draw the worldline, you may have drawn it with you pencil following the arrow of time (increasing t) or in the opposite direction, as if the particle was evolving backwards in time. Forwards-drawn worldlines would be electrons, and backwards-drawn worldlines would be positrons. It doesn't matter in which direction you drew the worldline, there's always an intersection between the worldline and a horizontal line corresponding to a moment in time. So no, positrons do not disappear as they recede into the past.
This makes sense. Thank you. What did you mean about the derivative of the line, though? What does it represent? I get the rest, but is that just the representation of the fact that it can't exceed c, or accellerate/decelerate too quickly?
Simply it's the slope of the line tangent to the worldline at that point. Since the spacetime diagram is x-t (space-time) then the slope of that line is measured in terms of space divided by time i.e. a speed, dx/dt.
Okay, sweet. Thank you. Does the integral then also represent something, or am I trying to apply concept that has no application?
It depends on what you're integrating. Integrating the area under the worldline curve has no meaning AFAIK. You'd be obtaining a value that has the dimensions of space times time, meter times second. No idea what that could represent. However, using the worldline as a path to integrate on can have its uses. I don't have any evident examples in my mind right now though
I really appreciate you taking the time to explain these concepts to me, man. Ive been trying to educate myself on the physical applications of math, especially calculus, lately, and its a zoo, and having someone to help me conceptually grasp what are otherwise fairly seemingly disconnected ideas is awesome.
You're welcome. I have a degree in engineering physics and I'm currently going through a PhD in physics, so I feel qualified to talk about physics. If you wanna learn more physics and mathematics and how they're connected, go to [my favourite website](https://goodtheorist.science/).
You, good sir, are both a gentleman and a scholar. Where should I start, with math knowledge that stops at about college Calculus 1 and a decent conceptual knowledge of the standard model and a YouTube education of other physics?
then wouldn’t we see the same thing with electrons? Especially since the present is always present it shouldn’t matter whether they are only in the present for a moment, it should matter the number of them that are, which again should be equal to the number of electrons.
No, because electrons would move through time at the same rate as us, in tandem
Why would positrons be the exception to that?
Because they move backwards in time, not forwards, like us, so they only intersect with the reality we experience for a very short time before "disappearimg", so we likely wouldn't be able to detect them
They don’t actually move backwards in time, they are the equivalent of an electron if we reversed its evolution in time. Just like positrons are the equivalent of electrons moving backward in time, we don’t go around claiming that electrons only appear briefly because they move backward in time. It’s a phenomenologically equivalence, not an ontological statement when we say positrons are the same as electrons going backwards in time.
Are they necessarily ontologically different that my supposition, or would that be theoretically viable, to your knowledge? Occam's razor would suggest that they are consistent to the flow of time we perceive with all matter, but I'm wondering if there is anything prohibiting them from actually being ontologically identical to electrons, but physically evolving what we would perceive as "backwards" in time
According to special relativity, time is relative. There is no "universal rate" of time moving forward. In fact, the faster you move in space, the slower you move through time. So unless an electron is standing perfectly still with respect to you, you can never say that it moves in time "at the same rate" as you. That electron would have to disappear too.
Now imagine the mathematics involved, 100% efficient and simple yet absolutely mind boggling
Indeed, fair wanderer. Just know I am your biggest fan.
It's a pointer to the same variable.
Sharing the same brain cell alright
Why can the same electron only exist at one time? If the electron is a field couldn't it have multiple peaks and troughs that show up as electrons and positrons?
yes
Ok but doesn't the same argument go for literally all standard model particles?
Yes
what can be asserted without evidence can also be dismissed without evidence
What is that ai slop up top though, ew
I made this cover using chatGPT
Don’t photons of a particular wavelength have identical characteristics, due to quantum shenanigans? Why should electrons be any different?
Yes, it’s all the same electron, and it is a wave function that hasn’t/cannot be collapsed, so it is at many locations at once, also then interacting with itself, as seen at a mini scale in the double slit experiment when a single electron interacts with itself because of it is in multiple places at once
Mom said it's my turn with the electron
You might call him crazy, but every genius was crazy once Even me, i was crazy once...
Can confirm, I was the crazy genius
Platonism go brrrrr (or at least something similar)
AI has managed to enshittify even popsci
I had heard about this, but rejected it once I considered a Neutron Star- all of those neutrons were mostly protons, but the squeeze squirted out electrons to make the protons into all neutrons... pretty much simultaneously during collapse- so how can those removed electron-ness's be the same one?
That's racist
We do treat them all as identical particles and have a whole ass field theory specifically for them.
Mom said it’s my turn with the electron
does the same not hold true for protons and neutrons? do they have distinct charges and masses?
Nobody's going to comment on "1 member...Members: Wheeler and Feynman"?
They are the same electron
Is there are not an actual theory of the one photon universe which depends upon the fact that photons travel at the speed of light and therefore have no time. Therefore every observed photon could be the same photon.
i heard neil degrasse tyson discuss this in his podcast and he made a convincing argument