CERN experiment proves gravity pulls antimatter the way Einstein predicted In sci-fi, antimatter is the opposite of all the matter around us. Does that mean it should fall up? Not at all, scientists at Europe's largest sub-atomic physics lab have proved for the first time. The result was predicted by Einstein's Theory of General Relativity more than 100 years ago, though getting experimental evidence …
《That rules out my plans for an anti-gravity drive based on a magnetically bound pot of antimatter. Now what am I going to do with it?》
So not Cavorite then.
Still a pot of say 1.0 kg of antihydrogen when "reacted" hydrogen very slowly should make a pretty decent rocket engine.
Slowly as 1kg x (300,000km/s)^2 an inconvenient number of Joules :)
> Ah, but as hydrogen balloons rise the fact that antihydrogen falls proves that it does do the opposite.
Ah, but to really prove that wouldn't you need to make a balloon... err... anti-balloon filed with anti-hydrogen and see what happens?
But then again maybe it would have anti-buoyancy to complicate things...
Just from half remembered physics books, this makes sense to me. Antimatter is a misnomer. Antimatter is still matter. It isn’t a case that Antimatter + Matter = 0 (because the annihilation produces energy - lots of it, and if antimatter was truly the opposite of matter the annihilation would produce exactly nothing.)
‘Antimatter’ is just matter with opposite spin.
"Opposite charge" would be better than "spin" ... at least for sufficiently general notions of charge (e.g. arguably dated usages such as where lepton number <-> lepton charge).
The problem with using "spin" is that - for the symmetry-based "spin", unless the object is spin zero, there is both a total spin and spin components; and the total spin is always positive, and the sign of the component is irrelevant to the particle/antiparticle determination.
Using "charge" in the generalized sense is also confusing, given that you might conflate/confuse it with (only) electrical charge; and not the specific implication of "oppositely charged to the normal (i.e. non-anti) version of the particle".
...It has the property we call 'gravity.' Therefore, it's no surprise that anti-matter, which is energy, has the same gravity as its matter counterpart.
I wish the realization that all energy has gravity would penetrate and become a universal understanding. Physicists make a lot of incorrect conjectures assuming the opposite. Call it "anti-physics." Can we move along please?
So, we can't explain the expansion of the universe without more matter than we can account for. We think we know that the universe started out with an equal amount of "normal" and "anti" matter except we can't find the expected anti-matter. So can someone explain why we think dark matter is a thing and maybe it's not just lots of anti-matter out where we can't see or detect it? I'm no astro/nuclear/particle physicist and I'm having trouble getting my head around this.
If there was a load of anti-mater in the universe we would certainly be able to 'see' as it interacts with normal mater quiet well. Dark mater on the other hand, if is actually exists, keeps itself to itself as far as interacting with the stuff we can see. Oh, and by the way, we can 'see' quiet a long way, almost back to when the first stars were forming.
p.s. As for an equal amount of mater and anti-mater at the beginning, still just a theory. There is some wiggle room with the CERN experiment which might yet show that anti-mater behaves differently than mater in some crucial way which might account for it's lack of existence in the universe we observe. Perhaps it might go some way to explain why less anti-mater than matter formed during the big bang leaving the mater we can see. Or, perhaps we are just wrong about the big bang and all that.
One line so far, see https://www.nature.com/articles/s41586-018-0435-1
"The transition frequency at a field of 1.033 tesla was determined to be 2,466,051.7 ± 0.12 gigahertz (1σ uncertainty) and agrees with the prediction for hydrogen to a precision of 5 × 10−8."
What if we are looking at distant galaxies with normal spectra, but they are entirely antimatter? How could we tell the difference? If the matter and antimatter separated out in the early universe, then maybe there is the same of each, just isolated into galaxy or galaxy cluster clumps.
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