Antimatter still has a positive mass. It's not some exotic negative mass matter.
Well, yes, as far as our theories go. But we also "knew" that light was a wave that traveled through the luminiferous aether, which permiated all of space... Until we tested that theory with the Michelson-Morely experiment, and it turned out our theories were completely wrong and physics as we knew it was completely upended.
Point being, it's important to actually test our theories instead of assuming they're completely correct just because most of their predictions are accurate.
Science advances by testing the limit cases. You do it and you do it until one day you get an unexpected result. That result, and the subsequent understanding of why it happens, is what leads to Nobel Prizes.
Aether was a fudge and pretty sure Einstein knew it. Forgot the exact history, but it was made up from whole cloth to make the math work out.
Well yeah. The concensus at the time was that light is a wave, and waves need a medium to travel through, so they just made up some stuff that must be everywhere and called it the aether. The null result of the interferometer experiment is part of what led to the discovery that light is a particle that acts like a wave, and so doesn't need a medium.
I'm pretty sure every physicist in existence knows that. It's just a simple principle that's really hard to test, so actually testing it is pretty cool. Like dropping a steel ball and a feather on the Moon.
It has a positive mass, and in every other way it acts just like normal matter going backwards in time (cpt inversion).
If, despite its positive mass, it was pushed back by gravity, then it would have given even more weight to the theory that antimatter is just matter moving backwards.
Since gravity is such a wonky interaction, I'm not even sure this result disproves the time-reversal theory entirely!
Why would inverting charge make particles go backwards in time? Electrons have opposite charge to protons and they don't seem to. Positrons have the opposite charge to electrons and as far as I know they don't go backwards?
I think you're misinterpreting cpt reversal symmetry, which is if you mirrored the universe in terms of charge, time and parity it would essentially evolve the same
It's been many years since I was invited with particle physics, so it's a bit muddled in my memory... i could be wrong on the details here. It could be the CP symmetry instead of the CPT symmetry.
It's not that positrons go back in time, but more like "if an electron went backwards in time, it would look exactly like a position". The Feynman diagram of an electron and position annihilaton is the same as that of an electron bouncing on photons, expect the angle is rotated such that the electron bounces backwards in time.
https://commons.m.wikimedia.org/wiki/File:Feynman_EP_Annihilation.svg#mw-jump-to-license
Ah yeah makes more sense
If an anti-gravity particle does exist (that expels both normal mass and itself), it would be incredibly hard to find.
They would push away from each other and disperse outside of the solar system.
Like 1 particle per 1000sq km kind of thing.
Which would push all the galaxies away from each other, always accelerating away from each other, but in a decreasing fashion....
It would also press inward on galaxies making it look like mass on the outer rims of galaxies having more gravity than they should.
And there would be a SHIT ton of this matter, that would be dark because it's so spread out,
..wait a minute ..
Dark energy is not galaxies moving away from each other but instead its new space being created in between which makes it appear like they are moving away from each other. That's why distant redshifts can exceed the speed of light, because they are not really moving, so the speed of light law is not broken.
Could it be a particle that has negative mass ?
In this case it would not appear in the CERN.
I'm way out of my field so please anyone, correct me if I'm wrong.
The CERN is creating particles from pure energy, E=mc² means that if you focus a lot of energy in a single point some of the energy is turned into matter. From my understanding the generated matter is random particles.
Now if we want to create a particle with negative mass we need negative energy. What is negative energy? I have no idea but if we manage to focus a huge amount of negative energy we will get particles with negative mass.
Do we need negative energy?
Don't particles appear out of thin are and then collide again and disappear?
0 = E = -mc² + mc²
You can have negative mass without requiring negative energy.
Whoa!!!
You may be on to something here!
I have a basic understanding of CERN, but if it comes down to it, everything they do there still blows my mind.
Like, imagine being the person who designed that experiment.
“Here is a CERN. Find out how antimatter falls.”
And some one/team was like ok I got this. And then they showed up one day & did it.
“Down. It goes down.”
I know it was much more complex than that, but still…imagine having the brain that stores the information required to do this. It’s so fucking cool.
What you don't see is the hundreds of people and countless hours of work that went into stuff like this. None of it is one person just showing up and making it happen. Everyone has their specific skill set and role in the project, no one knows everything. We see the result, but the day to day of this work would look mind numbingly boring to most people. It's not about geniuses having inspiration strike and figuring out something amazing, it's about months and years of staring at spreadsheets, analyzing data, fixing your mistakes, double checking, running the test again. It's about not giving up not being wicked smart, though the people working on it are definitely smart. Also this is the expected result. We were sure it fell down not up already, this was a confirmation of that.
This is pretty accurate. I was part of a detector group that did a beam test at Cern this summer. Everyone there is super helpful and humble because they know it takes grit more than anything at the end of the day.
It amazes me that people have this much ability and brains to complete such things. Meanwhile look at me. sigh
It is many, many people working together. No one person has this much ability or brains, only by working together do we make big modern scientific discoveries.
I would say it's many people working together who also have abnormally amazing brains.
Reading stuff like this is super funny when you have absolutely no idea how any of this stuff works.
"Wow, antimatter falls down! Gravity sure do be like that!"
It confirms what pretty much everyone already assumed would happen, but it's one of those things that should be tested just in case. Plenty of times tests have been performed and unexpected results appeared, leading to advancements in science. So if (on the very off chance) it didn't interact with gravity as expected, that might have led to improvements in our understanding of general relativity and/or quantum mechanics, since gravity is one of the big problems we have in trying to marry the two theories
My understanding of CERN comes explicitly from Neon Genesis Evangelion (1995) and Steins Gate (2011) ...and possibly The Backrooms (2022)
I do not have the gumption to mess with shadow companies jimmies.
Steins gate was introduction to CERN for me. And it scared the shit out of me. No, thank you. You do you.
Well, it’s antimatter, not anti-gravity.
I've heard hypothecies that antimatter was normal matter going back in time. But this disproves it since it would have been going in reverse in gravity.
I don’t think it works like that, it’s not as simple as doing the opposite of what we would normally expect the flow of time to dictate.
Nope it doesn't. But if it did it would have been neat!
Unless antimatter is also antigravity and the two cancel each other out, making it look normal to us.
Correct, but negative matter might in theory work that way
Either way, they still do these tests just to check that their theories remain consistent across a variety of edge cases
If you think this is cool, there is a !boinc@sopuli.xyz project for the LHC (worlds largest particle accelerator) run by CERN. You can donate your computer's spare computational power and maybe find a new subatomic particle! I've been running it for years, very fun project to be involved in, no PhD required.
A side note, with the announcement of the raspberry pi 5, there's a lot of chatter about how the pi boards are big contributors to boinc.
So, they put all the antiatoms in a tin can, put it up high, then opened the top and the bottom of the can and saw which end they came out of. I love it.
Unsurprising really. It seems fairly apparent that gravity merely influences the geometry of the substrate in which all known forms of matter & fundamental forces operate within. Something would have to seriously be fucky for antimatter to act counter to that geometry given it is comprised of similar particles with opposite charge. I'd assume astrophysicists know this, but wanted experimental proof for what seems to be straightforward logic from things we have experimentally confirmed.
The real question is what form does this geometry use to exert influence on the matter operating within curved spacetime? How is that information carried and how does gravity interface with that?
Antimatter is not just matter with an opposite charge. It's matter with every type of charges (electromagnetic, strong and weak nuclear charges) inverted, as well as the "parity", that is the relative direction of its spin compared to its propagation direction, are all inverted.
If you look for "CPT symmetry", you'll find better explanations than this.
It basically boils down to this: invert the flow of time, and every particle will look like antimatter, while antimatter will look like normal matter.
It would have been very likely that antimatter moved backwards in gravity of it was normal matter moving backwards in time!
What the fuck seriously
There's also no real reason for there to be more matter than antimatter in the universe. Any sufficiently high energy action will produce equal amounts of matter and antimatter, but there's overwhelmingly more matter than antimatter floating around. It's one of the big questions.
I have all of it, and I will never share with any of you 
invert the flow of time, and every particle will look like antimatter,
You just wrinkled my brain.
🙃
🙂 actually.
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