Super-K

Super-kamiokande

Built in an abandoned mine, the "Super-K" neutrino detector surrounds 50,000 gallons tons of super pure water with 11,200 photomultiplier tubes. To give an idea of the scale, that object in the distance is two men in a rubber raft.

From PopSci.  More pictures here.

Comments

Neutrinos are ridiculously non-interactive. To give an example, when a huge star's core collapses, it creates about 10^46 J of neutrinos. The neutrino flux only deposits about 1% of its energy in the star's envelope, but even that is enough to blow off the envelope in a massive explosion (known as a "supernova").

The caption was from PopSci but Ken is correct so I have changed it. Thanks Ken!

Well, Ken, it still comes down to the same thing--symmetry being broken at the subatomic level. The difference in the initial ratio still has to be accounted for, which would inevitably come down to those subatomic processes.

The only way to escape that is to say that we're in an area of the universe that's locally matter-dominated, while for each matter-dominated part of the universe there's a counterbalancing anti-matter-dominated part of the universe. That's a view that's been considered and (I think) rejected by the mainstream.

Zehpyr, my thinking was exactly the same as yours when I read the article. My assumption was that the creation process was totally symmetric, so the original amounts of matter and antimatter must have been identically equal.

Then I went back and paid more attention to this sentence:

>>According to what we "know" about the universe, there should be roughly the same amount of matter and antimatter in the universe, ...>>

"ROUGHLY the same amount" might be correct, if the creation process were not symmetric, but rather a random process involving either/or discrete separate pieces. In that case, maybe there were "roughly equal" parts, and what seems to us to be a LOT of matter is merely the residue after most was annihilated.

To give an idea of the scale, that object in the distance is two men in a rubber raft.

Yes but it looks to be a wide-angle photo (possibly fish-eye though I'm not sure) which tends to make far objects seem smaller and/or farther than they really are. It's a similar effect to the "objects in the mirror are closer than they appear" effect from the convex side-view mirror.

Ken: If that was true we would expect to observe more radiation than we do (since matter-antimatter annihilation produces photons).

Zephyrus: The reason the notion of areas of matter and anti-matter was rejected was because we would expect to observe characteristic radiation from the border areas, and we don't.

>>Ken: If that was true we would expect to observe more radiation than we do (since matter-antimatter annihilation produces photons).>>

(We are now into a realm that I can talk about, but I don't *really* know about.)

Well, Ryan, if the massive annihilation took place in the space/time vicinity of the creation, then wouldn't there have been a humongous spherical front of photons projected outward from that point at that time with a speed of C? In that case, the photons would be travelling outward in a gigantic ever-expanding spherical shell whose radius would be far beyond us; in a sense, at the outer limit of the universe.

Can someone tell me what is this for? Will this be used for research for anti-matter and matter aspects?

>>... wouldn't there have been a humongous spherical front of photons projected outward from that point at that time with a speed of C? In that case, the photons would be travelling outward in a gigantic ever-expanding spherical shell whose radius would be far beyond us; in a sense, at the outer limit of the universe.>>

>>Not quite; the big bang took place everywhere because the universe was really, really small back then.>>

I guess I wasn't nearly as clear as I thought I was.

That was my exact point. The hypothetical "humongous spherical front" would have been humongous in amount, but not in diameter, which would have been originally concentrated in a nearly-point source. The expansion away from the point source would have been at the speed C, which would have been vastly faster than the expansion of the remaining unannihilated matter, which would have also been rushing away from the original point source. Thus, at any subsequent time the spherical shell of photons would be beyond the matter, and moving outward faster than the matter, thus rendering it undetectable to us pieces of matter.

If this model is correct, then we have no idea whether our perceived "abundance of matter" is really a lot, or really very little of the original total.

The Gursky "photo" of this site is probably the best (Kamiokande 2007), and I think that's where they got the idea of the guys of the boat.

Was honored to see such a good article!

There was no point source: if primordial matter-antimatter annihilation occurred, then it occurred everywhere. Ergo, we should be able to make predictions about, e.g., the background radiation.

That image is awesome, and pointing out the two men in the raft really shows the scale of it. Great!.

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