Tag: CPT symmetry

Symmetry And The Loopholes

On By rolcottIn Cosmology, Mathematics, UncategorizedLeave a comment

“So, we’ve got geometry symmetry and relativity symmetry. Is that it, Sy?”

“Hardly, Al. There’s scores of them. Mathematics has a whole branch devoted to sorting and classifying the operations and how they group together. Shall I list a few dozen?”

“Ah, no, don’t bother, thanks. You got one I’d recognize?”

“How about charge symmetry? Flip an electron’s negative charge and you’ve got a positron that has exactly the same mass and the same interaction with light waves. OK, positrons move opposite to electrons in a magnetic field which is how their existence was confirmed, but charge is s a fundamental symmetry for normal matter.”

“Oh, right, charge is a piece of that CPT symmetry you hung your anti‑Universe story on. Which reminds me, you never said what the ‘P’ stands for.”

“Parity, as in Charge‑Parity‑Time. Before you ask, ‘parity‘ is left-right symmetry. Parity symmetry says you can replace ‘clockwise‘ with ‘counterclockwise‘ in a system and the equations describing the system will give perfectly good predictions. Time symmetry is about time running forward or backward. The equations are happy either way. The CPT theorem says the three symmetries are solidly tied together — you can’t flip one without the other two tagging along. If some process emits particle X with clockwise spin, there’s some equivalent process that soaks up an anti-X if it’s spinning counterclockwise. Very firm theorem, lots of laboratory evidence for it from electromagnetism and the nuclear strong force. But.”

“But?”

“But Chien‑Shiung Wu did an experiment that showed the nuclear weak force doesn’t always obey CPT rules. Her worked proved we live in a handed Universe. She should have gotten a Nobel for that, but it was last century and the Nobel Committee was men‑only. Two theory guys copped the prize that should have gone to the three of them. The theory guys protested but the Committee ignored Wu anyway. Sometimes things aren’t fair.”

“Tell me about it. So the theory’s got a loophole?”

“Apparently, but to my knowledge no‐one’s found it. Some string theories claim to hint at an explanation but that’s not much help, considering.”

“Huh. Could the loophole maybe be an example of symmetry breaking?”

“Very good question. I think it’s a qualified probably but that’s a guess.”

“Sy, I think that’s the wishy-washiest you’ve ever been.”

“One of my rules is, when you’re going out on a limb be sure you’re properly roped to the tree. In this case I’m generalizing from a single sample.”

“You’re gonna tell me, right?”

   Professor Higgs presents
       the Higgs Bozo.

“Just the bare outline because I don’t want to get into the deep weeds. Back in the 1960s Physics was in trouble because the nuclear strong force particles that bind the nucleus together were found to have mass and move slowly. Strong‑force theory at the time said they should be massless and move at lightspeed. The theory depended on part of the potential energy varying with the symmetry of a circle. Then Higgs—”

“The Higgs Boson guy?”

“That’s him. Anyway, he published a three‑page paper showing that those binding particles aren’t controlled solely by the nuclear strong force. Because they have a charge they also engage with the electromagnetic field. Electromagnetism is a lot weaker than the strong force, but it’s strong enough to deform the theory’s circle into an ellipse. Breaking the circular symmetry in effect gives the particles mass and slows them down.”

“So where’s the boson come in? I thought it’s what makes mass for everything.”

“Absolutely not, probably. The protons and neutrons have plenty of mass on their own, thank you very much. It’s only those strong-force particles that gain mass, less than 1% of the nucleus total. But the whole story is a great example of how making a system less symmetrical, even a little bit, can completely change how it operates. We think that’s what drove the Big Bang’s story. The early Universe was so dense and hot it was a perfectly symmetrical quark soup — chaos all the way down. Space expansion opened successive symmetry loopholes that permitted layers of structure formation.”

<looking at hands> “I don’t feel unsymmetrical.”

“Trust me, deep down you are.”

~~ Rich Olcott

Big Bang│Gnab Gib?

On By rolcottIn Cosmology, UncategorizedLeave a comment

Anne’s an experienced adventurer, but almost exploding the Earth when she tried transporting herself into an anti‑Universe was a jolt. It takes her a while to calm down. Fortunately, I’m there to help. <long soothing pause> “Sy, I promise that’s one direction I’ll never ‘push’ to go again.”

“No reason to go there and big reasons not to. <long friendly pause> Hmm. You’ve told me that when you use your superpower to go somewhere, you can feel whether there’d be a wall or something in the way. That’s how you know to get to a safer location before you ‘push.’ Didn’t you get that feeling before you went to meet anti‑Anne?”

“No, it felt just like just any other ‘push.’ Why?”

“I’m curious. Could you feel for just a second in the direction opposite to anti‑Anne? For Heaven sake don’t go there! Just look, OK?”

“All right … <shiver> Now, that’s weird. There’s nothing there, except there’s not even a there there, if you know what I mean.”

“I think I do, and you’ve just given us one more clue to where you almost went. Whoa, no more shivering, you’re back here safe where there’s normal matter and real locations, OK? <another soothing pause> That’s better. So, I was assuming a binary situation, an anti‑Universe obeying a Charge‑Parity‑Time symmetry that’s exactly the reverse of ours. The math allows only the two possibilities. You observed ‘no there there’ when you tried for a third option. That’s support for the assumption.”

“How could we have even two Universes?”

“It goes back to the high‑energy turmoil at the Big Bang’s singularity. Symmetry says the chaos in the singularity should have generated as many anti‑atoms, umm, as many positrons and anti‑protons, as their normal equivalents.”

“Positrons?”

“Anti‑electrons. Long story. The big puzzle is, where did those anti‑guys go? One proposal that’s been floating around is that while normal matter and our normal CPT symmetry expanded from the singularity to make our Universe, the anti‑matter and reversed symmetry expanded in some kind of opposite direction to make the anti‑Universe. You may have found that direction. Here, I’ll do a quick sketch on Old Reliable.”

“Looks like some of the banged‑up painted‑up battle shields I saw a thousand years ago.”

“It does, a little. Over on the top left is our normal‑matter Universe with galaxies and all, expanding out of the singularity at time zero. Time runs vertically upward from that point. I can’t draw three spatial dimensions so just one expanding sideways will have to do, OK?”

“No problem, I do x‑y‑z‑t thinking all the time when I use my superpower.”

“Of course you do. Well, coming down out of the singularity into minus‑time we’ve got the anti‑Universe. I’ve reversed the color scheme because why not, although I expect their colors would look exactly like ours because we know that photons are their own anti‑particles and should behave the same in both Universes.”

“They do. Anti‑Anne looked just like me, white satin and all.”

“Excellent, another clue. Anyway, see how minus‑time increases in the negative direction as the anti‑Universe expands just like plus‑time increases positively for us?”

“Mmm, yeah, but we only call them minus and plus because we’re standing outside of both of them. Looking from the inside, I’d say time in each increases towards expansion.”

“Good insight, you’re way ahead of me. That’s what I’ve drawn on the right side of the sketch. The two are perfectly equivalent except for CPT and anti‑CPT. Time direction, x‑y‑z space directions, even spin orientation, can all be made parallel between the two. However, the charges are reversed. Anti‑Anne’s atoms have positrons where we have electrons, negative anti‑protons where we have positive protons. When anti‑matter meets matter, there’s massive energy release from equivalent charged particles neutralizing each other.”

“Wait. Gravity. Wouldn’t anti‑matter particles repel each other? Your picture has galaxies and they couldn’t grow up with everything backwards.”

“Nope, you’re carrying this model too far. The only thing that’s reversed is charge. Masses work the same in each symmetry. Gravity pays attention to mass, not charge, and it’s always a force of attraction.”

“Anyway, not going back there.”

“Good.”

~~ Rich Olcott

Avoiding A Big Bang

On By rolcottIn Cosmology, UncategorizedLeave a comment

<fffshwwPOP!!> … <thump!> “Ow!”

That white satin dress, that molten‑silver voice. “Anne? Is that you? Are you OK?”

“Yeah, Sy, it’s me. I’m all right … I think.”

“What happened? Where’ve you been all year? Or considering it’s you I should ask, when’ve you been?”

“You know the line between history and archaeology?”

“Whether or not there was writing?”

“Sort of. Anyway, I’ve crossed it dozens of times. You wouldn’t believe some of the things I’ve seen. The professionals sure wouldn’t.”

“Wait, does the dress go with you? White satin wasn’t a thing centuries ago.”

“Oh, it changes like camouflage when I travel. That’s one reason I like this era — white satin’s so much nicer than muddy homespun or deerskins, mmm?”

“Mm‑hmmm. I suppose that’s why the dress didn’t get messed up when you erupted here. What led to that, anyway?”

“I don’t know. It probably had something to do with me experimenting with my ‘pushing’ superpower, going for a direction I hadn’t tried before. I’ve always known that front‑and‑back ‘pushing’ moves me forward or backward in time. You helped me understand that a ‘push’ to the side shifts me between alternate Universes at different probability levels. ‘Pushing’ up or down changes my size. Well, this morning I figured out a different direction to ‘push’ and that was weird.”

“You’ve described all three normal directions of space, so a new one would have to be weird.”

“I know what that direction feels like even if I can’t describe it. What was weird is what happened when I tried ‘pushing’ there. Things came into focus a little slowly. That may be what saved me. What I saw in front of me was … me. Dress, hair, everything, reflected left‑to‑right like looking in a mirror but our movements were a little different. Things were sharpening up and suddenly this sheet of fire flared between us and it blew me … here, to your office. What was all that about, Sy?”

“A couple of questions first. That sheet of fire — did it have a color or was it pure white?”

“Not white, more of a bright blue-violet.”

“And did it start like <snap> or were there preliminary sparkles?”

“Umm .. yes, there were sparkles! In fact I was already ‘pushing’ away when the bad flare‑up started. How did you know?”

“Just following a train of thought. I’m hypothesizing here, but I think you just barely escaped blowing the Earth apart.”

“WHAAATT!!?!”

“It all goes back to the Big Bang and our belief that physical phenomena have fundamental symmetries. Back in the Universe’s first few skillionths of a second the energy density was so high that the electromagnetic and nuclear forces were symmetry‑related. Any twitch in the chaotic unified force field was equally likely to become a proton or an anti‑proton, matter or anti‑matter. So why is anti‑matter so rare in our Universe?”

“Maybe the matter atoms just wiped out all the anti‑matter.”

“Uh‑uh. By symmetry, there should have been exactly as much of each sort. If the wipe‑out had happened there wouldn’t have been enough matter left over to make a single galaxy, much less billions of them. But here we are. Explaining that is one of the biggest challenges in cosmology.”

“You say ‘symmetry‘ like that’s a sacred principle.”

“I wouldn’t say ‘sacred‘ but the most accurate physical theory we know of is based on the product of Charge, Parity and Time symmetries being constant in our Universe. If you take a normal atom and somehow reverse both its charge and spin to get an anti‑matter atom, the symmetries say that the reversed atom must travel backward in time. From an outsider’s perspective it’d be like the original atom and the anti‑atom rush together, annihilate each other and release the enormous amount of energy that accomplished the reversal. Anne, I think you almost ‘pushed’ yourself into an anti‑Universe with a reversed CPT symmetry.”

“Those blue-violet flashes…”

“…were atoms from the air you carried with you, colliding with anti‑atoms in your anti‑twin’s air. Good thing those micro‑collisions released enough energy to get you back here before…”

“…I touched anti‑Anne or even breathed! <shiver> That would have been…”

“…BLOOEY!”

“This is nicer, mmm?”

~~ Rich Olcott

Worlds Enough And Time Reversed

On By rolcottIn Cosmology, General: Fun Stuff, UncategorizedLeave a comment

Cathleen unmutes her mic. “Thanks, Kareem. Our next Crazy Theory presentation is from one of my Cosmology students, Jim.”

“Thanks, Cathleen. Y’all have probably heard about how Relativity Theory and Quantum Mechanics don’t play well together. Unfortunately, people have mixed the two of them together with Cosmology to spawn lots of Crazy Theories about parallel universes. I’m going to give you a quick look at a couple of them. Fasten your seat belt, you’ll need it.

“The first theory depends on the idea that the Universe is infinitely large and we can only see part of it. Everything we can see — stars, galaxies, the Cosmic Microwave Background — they all live in this sphere that’s 93 billion lightyears across. We call it our Observable Universe. Are there stars and galaxies beyond the sphere? Almost certainly, but their light hasn’t been in flight long enough to reach us. By the same token, light from the Milky Way hasn’t traveled far enough to reach anyone outside our sphere.

“Now suppose there’s an alien astronomer circling a star that’s 93 billion lightyears away from us. It’s in the middle of its observable universe just like we’re in the middle of ours. And maybe there’s another observable universe 93 billion lightyears beyond that, and so on to infinity. Oh, by the way, it’s the same in every direction so there could be an infinite number of locally-observable universes. They’re all in the same space, the same laws of physics rule everywhere, it’s just that they’re too far apart to see each other.

“The next step is a leap. With an infinite number of observable universes all following the same physical laws, probability says that each observable universe has to have twins virtually identical to it except for location. There could be many other people exactly like you, out there billions of lightyears away in various directions, sitting in front of their screens or jogging or whatever. Anything you might do, somewhere out there there’s at least one of you doing that. Or maybe a mirror image of you. Lots of yous in lots of parallel observable universes.”

“I don’t like that theory, on two grounds. First, there’s no way to test it so it’s not science. Second, I think it plays fast and loose with the notion of infinity. There’s a big difference between ‘the Universe is large beyond anything we can measure‘ and ‘the Universe is infinite‘. If you’ve been reading Sy Moire’s stuff you’ve probably seen his axiom that if your theory contains an infinity, you’ve left out physics that would stop that. Right, Cathleen?”

Cathleen unmutes her mic. “That quote’s good, Jim.”

“Thanks, so’s the axiom. So that’s one parallel universe theory. OK, here’s another one and it doesn’t depend on infinities. The pop‑science press blared excitement about time‑reversal evidence from the ANITA experiment in Antarctica. Unfortunately, the evidence isn’t anywhere as exciting as the reporting has been.

“The story starts with neutrinos, those nearly massless particles that are emitted during many sub‑atomic reactions. ANITA is one kind of neutrino detector. It’s an array of radio receivers dangling from a helium‑filled balloon 23 miles up. The receivers are designed to pick up the radio waves created when a high‑energy neutrino interacts with glacier ice, which doesn’t happen often. Most of the neutrinos come in from outer space and tell us about solar and stellar activity. However, ANITA detected two events, so‑called ‘anomalies,’ that the scientists can’t yet explain and that’s where things went nuts.

“Almost as soon as the ANITA team sent out word of the anomalies, over three dozen papers were published with hypotheses to account for them. One paper said maybe the anomalies could be interpreted as a clue to one of Cosmology’s long‑standing questions — why aren’t there as many antiprotons as protons? A whole gang of hypotheses suggest ways that maybe something in the Big Bang directed protons into our Universe and antiprotons into a mirror universe just like ours except charges and spacetime are inverted with time running backwards. There’s a tall stack of maybes in there but the New York Post and its pop‑sci allies went straight for the Bizarro parallel universe conclusion. Me, I’m waiting for more data.”

~~ Rich Olcott