time travel happens all the time

you may not realize it, but time travel is not only possible, but it really happens. all the time. it is incredibly common. here is how it usually works, in everyday life:



the diagram above shows how the most common type of time travel occurs. a positron is an electron going backwards in time. note how the photon is at a 45 degree angle in the diagram. a 45 degree angle means that it is going at the speed of light. a steeper angle indicates something is moving slower than light speed. since electrons and positrons are both matter (or rather, a positron is antimatter, which is matter going backwards in time), neither of them can move at the speed of light; they both go slower. and nothing can go faster than light speed. so anyway, what happens in the diagram above? what the hell is going on there?

here is the first way to describe it. the electron is just bumbling along, minding its own business, and then suddenly decides, hey, i think i am going to radiate some energy, in the form of a photon. so the electron shoots a photon off at the speed of light, and the recoil from shooting off the photon propels the electron backwards in time. kind of like when you shoot a shotgun and the recoil from shooting the shotgun pellets so fast knocks you backwards. well, time is just another dimension like space, right? so the electron was shooting off a photon the same way you can shoot a shotgun, and it clean knocked the durn electron back in time. git er done! so then the electron is now called a positron, since it is going back in time, and anything going back in time switches from being matter to antimatter. about this time, the universe starts to get pretty pissed off about the antimatter existing, plus the positron, a.k.a. electron moving backwards in time, is hard up for some energy, like some kind of whacked out drug addict with no money who can’t afford to buy his/her next fix. remember how the electron had suddenly decided to shoot off a photon for no reason? crazy stuff. but sometimes electrons do stuff like that, if they are the wild and crazy type. so yeah, the universe says, hey, i’ll send a photon to hit that positron head on, and knock it back to its senses so it is an electron going forward in time again. and whaddaya know? it happens. the positron gets hit by a photon, and bam! suddenly everything is normal again, and the electron is going forwards in time again. but, for a certain period of time, there are 3 copies of the same electron, simultaneously existing. except one of them is going backwards in time, so it counts as -1 copies. so actually there is just one copy, since 2 of them cancel out. technically. but you and i both know, there are 3 copies of the same electron existing at once. it is possible to do this to more than just an electron. people have actually done this shit with entire atoms, and maybe someday they will be able to send people back in time. but that would be really fucking hard to do.

ok, so what is the more conventional way to look at this, for people who don’t like time travel? well, according to the conventional model, time is always going forwards. so, in the conventional model, the photon and electron are both just going along, minding their own business. then, the photon suddenly decides to split into an electron and a positron, one particle each of matter and antimatter. the new electron goes off into the distance, while the positron collides with the old electron. and bam! they both get obliterated, destroyed, in a flash of energy, shooting out a new photon, which just happens to be identical to the old photon, going in the same direction, with the same amount of energy. so, how the fuck is all of this shit possible?

well, this dude named richard feynman was a physicist, and he helped come up with a theory called quantum electrodynamics, or q.e.d., and he wrote a book about it, called qed. i was reading the book and that is where i found out about this shit. you see, in the q.e.d. theory, people use feynman diagrams, things with lots of arrows in them, like the one above that i show. well i am not sure if it is a feynman diagram actually, but it is just like one he had in his book, except instead of using colors to tell the electron, positron, and photon apart, he used different types of lines, either wavy lines or straight lines. ok. anyway, in this theory, you have to look at all possibilities, even ones that seem ridiculous. so, why on earth would anyone come up with this possibility?

well, when light is going through a material, it does not actually go at light speed. what the fuck?!? but no, it’s totally true. ya see, light keeps hitting electrons, which absorb the light, and then a little while later, the electrons release the light. then the light keeps on going, but it is running late, because it got held up in traffic by the goddamn electron that cut it off. so, we can observe the state of a system, before and after all this happens. the electron and photon both start at certain points, and both end at certain points, and in between, something happens. but there are like, a bunch of totally different possibilities as to what happens in between, and practically anything is possible. maybe the photon hits the electron, the electron changes direction for a bit, and then the electron shoots the photon off again, and goes back in its original direction again. maybe the photon hits the electron and is shot off from the photon at the exact same instant. or maybe the electron shoots off the photon before it absorbs the photon. there are like, an infinite number of ways this can happen. and in a certain percentage of the possibilities, stuff actually goes back in time, for a little while. that is just how it works. and this shit is indisputable. the theory that says all this happens, quantum electrodynamics, has been confirmed to be true, to an incredibly high accuracy. it is much more accurate than newtonian physics or the theory of relativity, in describing the physics of these interactions between electrons and photons. q.e.d. is a great success story of 20th century physics. and richard feynman wrote an excellent book all about it, where we find out about these seemingly absurd consequences of the theory. but, isn’t it cool that stuff can go back in time? maybe someday, we will be able to build time machines, and go back in time to change history. we can already send entire hydrogen atoms back in time (first done in 1995 by the physicists at cern in switzerland). and we have been able to send electrons back in time as positrons for up to 2 weeks, according to feynman’s book. when stuff is converted to antimatter and going back in time, it has to be kept away from actual matter, or else it will be vaporized and turn into light. not fun. so, if someone builds a time machine, they should test it out on animals before any humans try it out. it might not be very safe. i’m just warning ya. still, it might be a lot of fun, even if it’s dangerous. actually, i don’t think it would ever be feasible to send an entire human back in time. even a single atom is incredibly difficult to send back in time, so imagine sending billions of them back in time. in 1995, they only managed to send 9 of them back in time, and each hydrogen atom only managed to go back in time by about 40 nanoseconds, or 40 billionths of a second. not very promising.

but what is remarkable is, when sunlight is going through a glass window, at least some of it interacts with the electrons in the glass in the way i described above, causing electrons to go back in time. this also happens when light is going into your eye, or going through water. it even happens a little when light is going through the air. this interaction between photons and electrons is what slows photons down and results in the index of refraction for a material. it is why stuff underwater in a pool looks funny if you look at it from above the pool. antimatter is all around you! you just need to pay attention, and you might notice it next time. just read richard feynman’s book qed and find out about it. so why is there so much more matter than antimatter? because time goes forwards. otherwise, we would be stuck at the big bang (the beginning of time), since time wouldn’t be going anywhere. obviously there wasn’t any time before the beginning of time, so the antimatter had a hard time existing back then, since time went backwards for it, and it got stuck at the beginning of time and had to turn around in the time dimension and become matter again. matter, on the other hand, can keep existing forever, since time goes forwards for it. so that is why there is so much more matter than antimatter, and why nowadays antimatter particles have such short lifetimes. it is because the universe does not want anyone fucking around with time and making things go backwards. you can still do it, but the universe tries to stop you by sending matter to annihilate your antimatter. what can you do to defend yourself? usually, scientists use a strong magnetic field. if you are sending a charged particle back in time, you can also protect it with an electric field, which helps a lot more. since a hydrogen atom is not charged, it is much more difficult to protect when it is going back in time, so you cannot send it as far back in time. that is just how it works. neat, eh?

now you might be wondering, hey what about paradoxes when you go back in time, or can you remember the future, or stuff like that? well, apparently there are not any real paradoxes about any of this. it just works. quantum physics is really messed up, especially when you get down to the nitty-gritty of what happens at a subatomic level. it seems to violate all sorts of traditional notions of how things should work. but who cares? this is how the universe works, and the universe does not care if you think it is weird. the universe will continue to be weird, regardless of what your opinion about how it operates is. so, you might as well try to understand how the universe operates. and try to remember that antimatter is the same thing as matter except it is going back in time. now what about light? can you send light back in time? yes, but time never passes for photons, because at the speed of light, time is slowed down to zero, according to the theory of relativity. and only things with zero mass, like photons, can go that fast. they always go that fast, although sometimes they seem like they are going slower, because they keep being absorbed and re-emitted by matter. even in a vacuum, light will occasionally split up into a matter particle and an antimatter particle for a little while, and then the matter particle and antimatter particle will recombine into a photon again. this slows down the light, since matter and antimatter move slower than light. these random things happen because of quantum uncertainty. you never really know exactly what will happen, you only have probabilities. but you know what? lenses are amazing. they change the direction of light, by taking advantage of how light goes slower through a lens than through the air, and having different widths in different areas. the lens in the human eye does that. and so do corrective lenses, and telescopes, and microscopes. and in all the equations, when you add up all the probabilities, they must always have a sum of 100%, or else there is an error. and without accounting for the possibility of antimatter and things going back in time, the equations would not come out right. without antimatter, your glasses would not work, since there would be a paradox. amazing...