Scientists at Fermilab close in on fifth force of nature

TinyPizza@kbin.social · 1 year ago

Scientists at Fermilab close in on fifth force of nature

IHeartBadCode@kbin.social · 1 year ago

Part 2 - g-factor.

So back to our equation µ = g(e/2m)S. If the exchange between two electrons is just a single virtual photon, that g = 2. But if say the electron emits two virtual photons and then absorbs two virtual photons, that g now equals 2.0011614. We can find this value out with some fancy math. And this “correction” as it’s called was first calculated by Julian Schwinger in 1949. But as we go, we can toss into that calculation three virtual photons. And then toss in three virtual photons plus one of them become a virtual electron/positron pair, that cancels each other out into a virtual photon. This moves that g a tiny bit up to 2.0023193.

Eventually we hit a point where calculating this by hand gets hard to do, but we have super computers now that can do thousands upon thousands of theses corrections and we arrive at a g-factor of 2.0023193043552. However we measure by spinning, physically not the quantum spin, an electron in a particular direction and then setting that spinning electron in an external magnetic field how long it takes the electron to align with the external field. Much like the compass and Earth’s magnetic field eventually align. Now the electron can never perfectly align because of the particle’s quantum spin and so the electron has a precession (much like a top will precess around its axis) , we can also measure the g-factor of the electron from this precession called Larmor Precession. We measure the g-factor this way at 2.00231930436146. The difference between the g = 2 and the g-factor we measure or calculate is the anomalous magnetic moment of the electron. The difference between the calculate and the measured g-factor comes down to the fine structure constant, but they agree.

Now we move to the muon, which is like the electron but much more massive. Chances to exchange with virtual particles is the square of the mass of the particle, so a more massive particle the more likely it will exchange virtual particles. Since the muon is so much more massive (40,000 times massive) than the electron, the likelihood that there will be virtual gluon exchange or virtual Higgs exchange is much more likely. So we do our thing of plugging all of that into a super computer to get the calculate g-factor. We then do our experiment where we spin it like a top to get the g-factor that way. Then we look at the two values and take into consideration the fine structure constant. And that’s this experiment. And what they found is that the two numbers are off, by a quite a bit. Enough to point out that our super computers aren’t taking into consideration all the various virtual exchanges that COULD happen. AND THAT is what the big deal is.

IHeartBadCode@kbin.social · edit-2 1 year ago

Part 3 - What it means

The super computers have all the expected virtual exchanges programmed in, so if we’re off enough to indicate that we don’t have all the virtual exchanges programmed in, then we’re missing a fifth kind of virtual exchange that needs to be programmed in, and that may mean there’s a fifth force (since all virtual exchanges derive from an actual field).

However, this won’t tell us WHAT it is. This is just one way of finding a path to go down. We’ll need entirely different avenues to take that path down to discover the actual force. Basically, we’re balancing our checkbook and the bank statement, but in the end the checkbook is off by a few dollars. So there has to be some bank transaction in the statement we forgot to write down. So this being off tells us that we’re missing something, but doesn’t tell us what we’re missing.

Additionally, Fermilab confirmed with a sigma of 4.7, which is short of 5 sigma which is needed to claim a discovery. So spinning muons that decay in a few microseconds is pretty hard and with just random cosmic electrons and nuetrinos and what not flying through the air, there’s a lot of “noise” on the wires that are measuring the spinning of those muons. So they have to keep working to get a cleaner and cleaner signal. Additionally, once they hit five sigma, they have to repeat it. And then, they have to submit their experiment so that someone else can independently do it as well and they have to hit five sigma. Because in the end, the very experiment they’re doing might be what’s tossing all the values off to begin with. That is their machine is just fundamentally flawed. That’s that consistent but inaccurate that gets covered in high school science. Independent confirmation ensures that someone else builds a machine that aims for the exact same goal but in their own very special way.

So it’s a very long road ahead, just so that it can be shown that there is indeed something missing from the calculations. But that’s way better than where everyone is right now, not knowing where to look for more physics. If this all pans out, what it points to is there is a fifth force that is very, very weak and that means it’ll be difficult to coax it to come out on display so that we can study it. Just the fact that on a muon were talking differences of just a few thousandths means this force is much weaker than the weak force. What role it plays? What does it mediate? No one knows, that’ll have to be different experiments. In fact, just like it might not be a single transaction that throws your checkbook off from the statement, same diff, we may be talking about multiple forces, no one knows.

But like all things. This will CONFIRM we are missing some part from the standard model. And that is a big deal. Because right now, everyone thinks we’re missing some critical parts, like dark matter and dark energy, but we’ve got equations that might be right that allows our universe to exist without dark matter and dark energy. But we don’t know either way. THIS WILL CONFIRM WE’RE MISSING SOMETHING. That is hugely exciting. Not often you hear people getting excited over “WE DON’T KNOW EVERYTHING!!”