Our Antimatter, Mirrored, Time-Reversed Universe

The foundations of quantum theory are based on their symmetries, for example, it should be impossible to distinguish our

universe

from one that is a perfect opposite mirror in terms of lateral charge and

time

direction, but one by one it was discovered that these symmetries They were breaking, threatening to break everything. of physics along with them. In his famous lectures on physics, Richard Feynman talks about what it means to expect the mirror-identical

universe

to be evenly symmetrical and invites us to imagine a clock reflected in a mirror. The upside-down component numbers are flipped from left to right and tick counterclockwise and then he asks us to imagine building that same mirror clock.

In reality, everything is built as if

mirrored

: the numbers are painted upside down, each screw with a right-hand thread or right-hand spiral coil. is replaced by a left-handed version, our intuition tells us that the mirror clock should work exactly the same except counterclockwise; our intuition would be wrong. The laws of physics and therefore the laws of clocks are not symmetric to this type of parity transformation, as we saw in our recent episode. The experiment that first demonstrated this found that cobalt-60 nuclei decay by splitting an electron in the direction opposite to its nucleus velocity axis, but in a mirror-reflected universe, the same decay should be in the direction opposite, so with that spin axis, which is a fundamentally different physical behavior.

So what does this have to do with Feynman's clock? since it proposes a clock whose ticking is governed by the disintegration of cobalt-60. Imagine a series of cobalt-60 atoms in a magnetic field, the cobalt nuclei have angular momenta that will align with a magnetic field, say upwards, so that the decay electrons travel downwards. A detector is placed to intercept those electrons and the clock ticks with each captured electron. In our

mirrored

clock we need to replace the cobalt atoms with their parity-

reversed

counterparts, but now the decay electrons travel up with the nuclear spin and away from the detector.

Such a clock would not work at all, taken to its literal extreme, a perfectly constructed mirror. the mirrored clock behaves differently, so what's the problem? Well, violation of parity symmetry represents a threat to even deeper symmetry. cpt symmetry the combined change of charge parity and

time

and this symmetry lies at the foundation of quantum field theory. Physics must work the same if we change all these properties, otherwise physics as we know it goes out the window, which seems like a big problem. To save physics, Richard Feynman proposes building a copy of our clock with

antimatter

. Uh... sure, Feynman, why not! electrons become positrons quarks become anti quarks and vice versa sending protons and neutrons to their anti versions in the nuclei of our now anti cobalt-60 and other antiatoms sending matter to

antimatter

is part C of cpt charge conjugation all charges change electric side charge, but also quark color charge, weak hypercharge, etc., that is what a change to antimatter means, how does this work on our Antion on a watch?

Well, antimatter atoms have negatively charged nuclei, which means their nuclear magnetic fields point in the opposite direction to regular matter relative to their Angular Momentum, the magnetic field in our clock will align the antimatter nuclei in the opposite direction. to matter nuclei, so in our mirror-reflected antimatter clock, the direction of the decay electrons is

reversed

once due to mirror reflection and again due to the change to outgoing antimatter. electrons travel in the original downward direction and the clock ticks normally, so although the universe does not have symmetric parity, perhaps it is under charge parity, a CP transformation is said from right to left and sends matter to antimatter at first glance, this CP symmetry appears.

To maintain not only in imaginary clocks but also in Standard Model particles, the big parity violation process is the weak interaction that only affects the left chiral fermions. Straight chiral fermions do not feel the weak force at all, but the opposite is true. Right chiral antimatter antifermions fill the weak force, while left chiral antifermions do not, so a charge parity change leaves you in the same situation with respect to the weak interaction. If CP is what we call good symmetry, then you shouldn't be able to do it. any experiment to find out if you are in this universe or a universe transformed by CP or physics should work the same theoretically, but don't get too comfortable, we haven't looked at what experimentalists have to say about that, you might remember from the episode of parity that the first indication of parity violation was the so-called tau theta problem that resulted from the fact that the positively charged Kaon meson decayed in ways that violated parity conservation.

It turns out that these Kaon particles are excellent in Finding the Universe Doing Strange Things in 1964 James Cronin and Val Fitch observed the results of the decay of neutral Kaons. These things are extra rare and common. K on is a quantum mixture of its own particle and antiparticle. There are two ways to make this mixture. producing two types of mutual Kaon once, let's call it KS, it is short lived and has what we call a uniform CP state, which simply means it does not change under a combined charge parity transformation, the other type KL is long lived and it has an odd CV state, its wave function is multiplied by -1 in a CP transformation and that means it is different from the KS state if CP symmetry is preserved.

KS and KL should never transform into each other because they have different CP symmetries proven by Cronin and Fitch. this by sending a bunch of both types of neutral Kaon down a tube with a detector at the other end. The KS particles should never have made the trip given their short lifetime, and yet a small but significant amount of decay products of the KS particles were found at the other end. The only explanation is that the KL particles oscillated in KS, violating charge parity conservation, that sucks. our mirror-reflected antimatter clock isn't working after all, kind Fineman, and that's not the worst of it.

Violation of CP symmetry has much more dire consequences than a broken imaginary clock, although it has a lot to do with time, this also suggests. that the reversal symmetry of time is broken and to understand this we need to reverse time a bit and go back to the 1950s, which coincidentally saw the breaking of another imaginary clock in Hill Valley, California. The 1950s were also the decade of the foundations of quantum field theory. When a SQFT emerged, it became clear that there is a certain symmetry that is not only intuitively expected but also theoretically required. Beginning with Julian Schwinger's "spin statistics theorem" in 1951, it became increasingly clear that quantum field theory requires symmetry under the combined action of charge conjugation parity inversion and time inversion.

The axiomatic foundations of QFT claim that an antimatter mirror reflected a time-reversed version of our universe. The universe should have exactly the same laws of physics. This is the CPT theorem. Quantum field theory should be CPT invariant and we know that quantum field theory is correct at least as far as the correct engine theory we ever devised is concerned. I will return to what this new symmetry of time reversal is. What T and CPT actually mean, but for now let's accept that the laws of physics must work the same under a simultaneous change of charge parity and time direction, which was certainly the opinion of physicists at that time. late 1950s, so then come experiments showing a violation first of P, then of CP symmetry; big deal, we still have T, CPT can be preserved.

But here's the problem: if CP symmetry is violated and CPT symmetry is satisfied, then T symmetry must also be violated, because that time reversal operation needs to take us from a broken CP mirrored universe to a fixed CP T universe, but that means a T transformation of our working CPT universe sends us to a broken CP universe. The Burgo time reversal transformation changes the way the universe behaves. In theory, time symmetry is ruled out. That sounds bad, isn't physics supposed to work the same whether we go forward or backward in time? Well, as we talk about in this episode, don't we absolutely need time reversal symmetry to preserve quantum information which in turn is necessary for all of quantum mechanics to make sense?

Well, to get to this we're going to need to talk about What we mean by reversing time. The most obvious interpretation of time reversal is to literally reverse the arrow of time and have the universe travel backwards in time. That's not what we mean by T in CPT, which I'll explain in a minute, but first let's think of this simple type of T transformation as a literal rewind. Rewind the universe and you're back to square one more or less by definition, so presumably quantum information is preserved in this kind of time trial. Mathematically, particles in a rewind universe actually appear to have undergone a charge parity inversion.

Matter moving forward in time looks like antimatter with inverted parity moving backwards in time. This interpretation of antimatter as matter reversed in time was first proposed by Ernst Stueckelberg in 1941, but is now largely associated with Richard Feynman; It is essential to his comprehensive approach to quantum mechanics and Feynman diagrams, perhaps why he was so interested in building antimatter clocks. So yes, the universe is not symmetric under this simple version of the T-inversion. It is the exact opposite of a CP transformation, the two undo each other. Do a CP transformation and then a simple T transformation and you'll be back to square one.

If CP is violated, then this simple reversal of time is also violated, and we see this violation in the asymmetry between matter and antimatter, then there's the whole entropy thing, although its connection to quantum mechanics is still not well understood, as I said. , this simple interpretation of T as Rewinding the universe is not what we normally mean by the T in CPT (T is more accurately thought of as reversing the direction of evolution of a physical system): an explosion becomes an implosion and the disintegration of particles becomes the creation of particles. You are not rewinding time, you are not converting matter into antimatter; you're just reversing all the momentum and spin.

Basically, you're taking all the particles in the universe and pointing them in the direction they came from. If the T in CPT is conserved, then after reversing all the motion of the particles, those particles should perfectly retrace their steps and perfectly reverse all the reactions in their histories. As this reverse-moving universe evolves forward in time, it should end up returning to its initial configuration. On the other hand, broken T symmetry says that if you make this reversal, the future will not perfectly reflect the past. A prediction of this T symmetry is that all processes should take the same amount of time forward as backward, for example a quantum transition between one type of particle and another should take the same time in either direction and that gives us a Proof: In 2012, physicists from the BaBar collaboration at the Stanford Linear Accelerator Center tested the speed with which B houses transition between two types in a T-symmetric universe.

The speeds should be the same in either direction, they were not. equals reversing the direction of the interaction changed something fundamental about the physics indicates a violation of T symmetry. But remember, removing T symmetry is a good thing because it can save CPT symmetry. The last 70 years have been a real roller coaster for nature's symmetries, as experiments found broken symmetries one by one, first parity and then charge parity, the sacred CPT symmetry seemed in danger unless we gave up the symmetry of time itself. but now that the time reversal symmetry also seems broken, the CPT theorem seems safe.

Feynman's mirror-reflected antimatter clock will work just fine, but in addition to moving every atom backwards, every subatomic particle also needs to move backwards, which is why we've discovered our perfect mirror universe. It is a reflection of all three: charge, space, time. Hello everyone, I'm back from the event horizon, aka. Australia, whichAs you know it is the inverted version of Canada's CPT. The last episode before the hiatus was "Why String Theory is Wrong." Today, I want to address the comments from that episode or catch up on last week's comments next time; In fact, I really want to address some points raised by FieldStrength on the PBS Space Time subreddit - they covered all the major points.

Now I first want to clarify that despite the title, "Why String Theory is Wrong," the point of the video was not to argue that string theory is wrong, but rather it was a fun continuation of why string theory is wrong. correct. I reiterate my real opinion on the matter after addressing specific strong points that very reasonable criticisms. In the video we observe that string theory largely requires supersymmetry to be correct and that supersymmetry has not yet been detected on the expected energy scale, which is the expected energy scale if supersymmetry also provides clear resolution to the hierarchy of standard models. problem, but string theory does not require supersymmetry to be on that scale.

For the purpose of string theory, supersymmetric particles could be well beyond the energies detected by the Large Hadron Collider, so FieldStrength argues that our current non-detection of supersymmetric particles is not Falsification of string theory and of course that is correct, but I didn't say otherwise; Apologies if it seemed implicit. However, I maintain that this non-detection is a bit counterproductive. Supersymmetry is very compelling if it provides an answer to the hierarchy problem and gives us superstring theory. It would be strange if supersymmetry existed as part of superstring theory but did nothing. to help with the hierarchy problem because it had too high an energy scale.

But, as I mentioned in the video, the current results from the Large Hadron Collider still don't completely rule out all useful energy scales for the hierarchy problem, just the energy scales that solved the problem most clearly. The other point of FieldStrength is that the large undefined parameter space of string theory (the so-called 'string landscape' is no more a problem for string theory than it is for the standard model), I totally agree. In fact, it is less of a problem for string theory because in the standard model many parameters are not irremediably constrained by the theory itself, while in string theory it is arguable that only one parameter is irremediably unconstrained.

What I mean is not that string theory is more wrong in the Standard Model, but that it is still not "correct", in this sense. To tell me, it was never really good and, to quote Peter Weitz quoting Pauli, "it's not even bad." The point is that while it's not wrong, there still isn't a way to properly test whether it's right or wrong. FieldStrength's final point is that the untestability of string theory is related to the extreme energy scale of quantum gravity, and that problem is not unique to string theory. We talked about that in our first episode on general quantum gravity, so we apologize for not repeating it here.

So yes, string theory is apparently not yet testable, but I disagree with those who say that this kind of lack of testability means the field is not science. String theory may not currently be testable due to the energy scales involved, but the universe is under no obligation to become currently testable with any particular technological level of particle collider construction. It has no obligation to make each next layer of reality accessible to the next generation of physicists. We have traversed several layers of reality, from atoms to quantum fields, in the last hundred years, but perhaps the next layer will take another thousand years or more.

Randy Copeland brilliantly points out that physicists are a bit like the 'House' doctor who tries to find a diagnosis that fits the symptoms and the symptoms are all reality itself. A good observation also makes me feel better about giving up my degree when I buy plane tickets in hopes of getting an upgrade. I still dread the day the crew comes to see me because there is some medical emergency on board and I have to tell them what kind of doctor I am.