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Today my physics teacher said that "A matter particle going forwards in time is sort of like an antimatter particle going backwards in time."
What did he mean by "sort of"?
What did he mean by "sort of"?
Vanadium 50 said:This may not be quite what you are looking for, but I have found that when a teacher says something I don't understand, it pays to ask him or her what (s)he meant.
HallsofIvy said:I believe that observation was originally due to Feynman. Draw something like a large "M" on a sheet of paper. Think of the space axis as horizontal and the time axis as vertical. Take a straight edge, place it horizontally across the bottom of the page and move it slowly up the page. Think of the points at which the lines cross your straightedge as being the positions of particles at the present time. Initially you have two particles that are moving toward each other. Think of the particle on your left as being an electron and the particle on the right as being a positron.
When your straightedge meets the central "V" of the "M", two new particles magically appear out of nowhere! That is a "creation pair"- a particle and its anti-particle, an electron and a positron. Now continue moving the straight edge up the paper. You now have two pairs of particle moving toward each other, one pair on the left, the other on the right. When you finally reach the two "/\" points of the "M" those two pair disappear: an electron and a positron have annihilated each other. The electron that was originally on the left has annihilated the positron that was created in the middle and the electron that was created in the middle has annihilated the postitron that was initially on the right.
Now lift your straightedge and look at the "M" itself. Do you see that you can think of that a single track: as an electron coming in on the left, moving "forward in time" then suddenly is turned "back in time" until, at the "V" it turns "forward in time" again , eventually hits the top "/\" and turns back in time once more. The movement "back in time" is what we, with our limited "one instant" perspective, see as a positron.
You might suspect that it would take some real cataclysm to change motion "forward in time" to "backward in time" and vice-versa. That's exactly right! It is the enormous energy, E= mc2, necessary to create an eletron-positron pair or given up when such a pair annihilates.
I have no idea how "serious" Feynman was when he proposed this but it does answer one basic question: All electrons are identical because there's really only one electron, bouncing back and forth in time!
malawi_glenn said:vacuum energy, the vacuum has energy in physics.
I do however have one question: How do the two new particles "magically appear out of nowhere"?
Antimatter is a type of matter that is composed of antiparticles, which have the same mass as regular particles but opposite charge. For example, an antiparticle of an electron is called a positron, which has a positive charge instead of a negative charge like an electron. When matter and antimatter come into contact, they annihilate each other, releasing large amounts of energy in the form of gamma rays.
Antimatter can be created in high-energy collisions, such as those that occur in particle accelerators. In these collisions, energy is converted into matter and antimatter pairs. Antimatter can also be created naturally in some radioactive decays and high-energy cosmic events like supernovas.
Antimatter plays a crucial role in our understanding of the origins and structure of the universe. The Big Bang theory suggests that equal amounts of matter and antimatter were created at the beginning of the universe, but for some reason, matter survived while antimatter largely disappeared. Studying antimatter can help scientists understand this imbalance and potentially shed light on the mysteries of the universe.
In theory, yes, antimatter could be used as a highly efficient source of energy. When matter and antimatter collide, they release a tremendous amount of energy. However, the technology and resources required to produce, contain, and harness antimatter are currently far beyond our capabilities.
The concept of time is closely tied to the study of antimatter and matter because they behave differently when it comes to the arrow of time. According to the laws of physics, matter and antimatter should have been created in equal amounts at the beginning of the universe, but we see a clear asymmetry between the two. Understanding this asymmetry could help us better understand the nature of time and its role in the universe.