Antimatter is just like normal matter – except all antiparticles have the opposite charge to matter particles. But why do some physicists think of antiparticles as travelling backwards in time?
In this video, we will be looking at two particle interaction processes that commonly occur in our universe. Then, we will see what links these two processes, despite initially looking quite different. Finally, we’ll learn a very basic (but not very rigorous) way to understand the notion that antiparticles move backwards in time.
The first process we will study is Compton Scattering. This occurs when a photon interacts with an electron. A photon carries some amount of energy, related to the wavelength of the source of EM waves from which it was created. The larger the wavelength, the less energy it carries. It’s worth noting though that all photons travel through space at the same speed – the speed of light.
So when a photon meets an electron, the photon can transfer some energy to the electron so that it starts moving through space. As a result, the original photon is said to be “absorbed” by the electron, and a new photon is released. This new photon has energy equal to the original photon’s energy minus the energy given to the electron. This way conservation of energy is obeyed. But also, conservation of momentum is obeyed too! The two new particles (new photon and electron) move through space so that the original photon momentum matches the electron and new photon’s momenta.
The second process looks at the interaction between an electron and its antiparticle, the positron. All particle that have the same values for all possible descriptors, e.g. mass, charge, spin, etc., are said to be the same type of particle. All electrons have the same mass, charge, etc. But if we take a particle and we now consider another one with all the same descriptors except the opposite sign of charge, then we are looking at the original particle’s antiparticle. In other words, the positron has all the same properties as the electron except it is positively charged rather than negative.
When a particle and its antiparticle meet, they annihilate each other and two photons are released. These two photons combined have the same amount of energy as the initial two particles had. This process is known as pair annihilation. And aside from involving similar particles to Compton Scattering, it seems to be quite different to Compton Scattering.
However, if we use “Crossing Symmetry”, we see that these two processes are not so different. When we write any of these processes in equation form, we can take any of the particles on either side (the reactant/before side or the product/after side) and move it to the other side of the equation, provided we turn it into its antiparticle. This is explained in more detail in the video.
If we start with pair annihilation and move the positron to the other side, while doing the same with one of the photons (using Crossing Symmetry of course), we end up with Compton Scattering! These processes are said to be inherently the same “process”.
But more importantly, Crossing Symmetry allows us to consider the idea that a particle on the “after” side of any equation would turn into its antiparticle on the “before” side. Since an equation showing particle interactions allows us to see how particles behave over time, we can therefore imagine that the antiparticle is moving backwards in time relative to the original particle. This is one of the very basic explanations of why antiparticles can be though of as moving backwards in time compared to their particles.
In reality though, the mathematics of particle physics makes it difficult to differentiate between a particle moving forward in time, and its antiparticle moving backward in time. That’s the true reason for this notion – though it doesn’t mean antiparticles do actually move backward in time! It’s just a cool thing to think about.
Thanks for watching, please do check out my socials here:
Instagram – @parthvlogs
Patreon – patreon.com/parthg
Music Chanel – Parth G’s Shenanigans
Merch –
Here are some affiliate links for things I use! I make a small commission if you make a purchase through these links.
Quantum Physics Book I Enjoy:
My Camera:
ND Filter:
Microphone (Fifine):
Gorillapod:
Timestamps:
0:00 – Particle Physics – Two Processes That Are Surprisingly Similar
0:50 – Process 1: Compton Scattering
2:30 – Antiparticles: The Very Basics
3:56 – Process 2: Pair Annihilation
4:26 – Crossing Symmetry
6:15 – Do Antiparticles Move Backwards In Time? A Visual Analogy
This, then, would create memory.
Antiparticles may be inverted particles. As an analogy an animation of a four dimensional tesseract hypercube imagining the inner expanding cube consisting of matter and electrons which twist in a space-time dimension, so that the inner cube passes through the outer cube in the fourth dimension, therefore not colliding in a neutral spin orientation in a continuous process, at the speed of light. The edges of the inner and outer cubes could be denoted by Feynman arrow fermions that would constantly changing direction, and the corners of the hypercube might be analogous to bosons.
Well, I don't buy the reasoning, we are just moving terms of an equation.
We have this kind of equation with reagents and products in chemistry but we never do that time contortionism.
It would be nicer to have a more mathematically rigorous explanation, as it is that backward in time is bs.
Edit: unless there's a "conservation of time" thing, even in the lines of CPT symmetry.
Hi everyone please reply me i want to go back and change my past please help me 🙏🙏🙏🙏
That was awesome 🤩
In the crossing symmetry explanation you makes it clear that either side of the equation can be seen as one was happening before and the other one is happening after.
I'm just curious to know whether this before and after concept, could be implied to any neumerical equation? Consider the equation 2+3=1+4
The way we perceive the arrow of time, is it an inherent charecteristic of our reality or it's an emergent feature of our reality?
I think entropy can be explained without the need of having a linear progression of time, but with the increase of probability ( with the increase of possible states of a system )
Maybe our mind is creating this time hallucination.
I know these assumptions might look funny to someone, as these assumptions are philosophical in nature. And I want to admit here that I am not a science guy. I'm just curious 🙂
Time reversal causation also works on the macro level. Before physical events occurs, say a car crash at an intersection, the event has already taken place in the higher dimensions. Take WWII. Is it not curious that the major players in the events such as Roosevelt, Hitler, Stalin, along the the Generals: Eisenhower, Bradley, Patton, and other players all incarnated on the average near the year 1890. Likewise, the countless soldiers were born near 1920. They were destined to be the players in the grand drama and CHOSE to incarnate so they could be ready to play their roles in the War. This planning took place on the higher dimensions, and in a sense, was "caused" from the future event of the War (1939 – 1945). In other words, the future casts a shadow into the past.
Yes, but anti-photons may appear to exhibit reverse causality.
E^n-1 +/-{E^n} involves a wavestate that is in both directions of time simultaneously.
Would have been interesting if you had related this to the way antiparticles are shown to travel backwards in time in Feynman diagrams of the particle interactions.
Three is no even remote explanation what is meant to move backwards in time while othet things move forward. Just parroting Wheeler and Feynmann phrase which means nothing.
Where is all the antimatter?
Could it be moving, in a 'negative time direction'
Phase is not invariant. Phase is only constrained by Pauli. Phase is part of a superposition. Hence, the ability to perform computation.
Parth, you have a very cheat and logical mind that makes your instruction so easy to understand. You also pause at the current times so we can digest your thoughts. Very well done!
If time was a compact dimension, spinning, a single Planck second shared by all points in space then we can evolve via kuramoto synchrony a phase hyperplane of the present. Time spinning in the plane. Flat. One side spinning one direction, the other side spinning (apparently) the other. If the axis of spin becomes out of plane of then you have inflows and outflows. Charge. An inflow on one side is an outflow from the other. Clockwise on one side is counterclockwise on the other. Antimatter is the other side of the temporal manifold.
This explains electron(and positron) half spin.
An electron does one orbit on this side as an electron but then has an internalized orbit on the other side as a positron. An electron here is a positron there. Conservation at every point in space.
The manifold itself is like a layer of photons but propagating 90° to us. An event horizon is vacuum energy laid bare. That's why it's black. The light is 90° to us.
That interpretation is wrong.
Zeatea boom yucky ….you come sucky my prepetual motion machine….. it's not a lazer beam ……. scaler is the angle… the square was in a tangle …..dangle dose the pendulum in a parabol ..if I was no fool.. I could see that the pendulum is dual … standing in motion was the magic potion… if people got it … flux could save you a few bucks …. . I once said seven f#@ks … as I fell twards.. but also away from the "crux "… the" circle" three to be …….as one was me and 2 is you and 3 is who …… concentric point…. is the focult dew …..how do you spell fountain too… the " sign "signal was sent quick beyond the concentric… 1 and 1 and 1 is 3 got to be good looking because he's too hard too see.. Templar… scaler..masonry .. its all free see ….
heres a video of how to create photons that go back in time. https://youtu.be/Qd77OXWC1eg
How to become a physicist and what we have to do after being a physicist🙏🏻
Please make a video on this🙏🏻
❣️I really love physics and universe
Why mass should be equal (acceptable) or "Less"????? Isn't it the violation of mass conservation?
Someone please enlighten ne..
Great video! Also, great outro song… where did you find that??
Your videos are truly the best resource to clearly explain these ideas. I have listened to hundreds of hours of podcasts and pop physics books and was always lacking an "understanding" of what certain quantum phenomena and when I'd search on youtube I could get close to an understanding, but definitely didn't get as close as I am after watching your videos. Please keep producing content, I'm sure your channel will explode.
It would be nice if crossing symmetry could be used in developing a way of thinking about Physics that does not lead inexorably back to the big bang that Human mind processes seem hard wired to demand.
If positrons do indeed travel backwards in time, then they can never be created, because the instant they are created they will disappear, as they have gone backwards in time, whilst the rest of the universe is moving forwards in time. Ergo, particles do not move backwards in time.
Neutrons have zero charge, and yet they have the anti-neutron as its anti-particle. Ergo, having an opposite charge is not the distinguishing feature of an anti-particle.
Crossing symmetry is not indicative of particles moving back in time, any more than a chemical reagent when moved to the other side means the reagent moves back in time.
Pauli exclusion principle can be interpreted as temporal direction.
A positron going backwards in time is also an electron.In Grassman Algebra
a field is a CatHole.(wormhole-wormhole with 360 twist)
hey I had a video suggestion. can you please react to the big bang theory
nice idea 👌
Parth. Why do so many geniuses post videos on youtube and yet act aloof when those who are on the journey they themselves began years earlier are seeking guidance?
You have managed to explain this complex topic it in a very simple way. Nice! I am currently taking Particle Physics course in my final year of UG
Hey Parth! I'll realy like to understand the Feynman's Diagrams. What about videos on the subject? Thanks