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Evidence Found for a New Fundamental Particle
- abnry 8y agoParticle physics is just crazy land to me. I understand Newton's equations. I understand Maxwell's equations. Hey, I even understand Schroedinger's equation. But all these particles!?
- 21 8y agoModern quantum physics starts after Schroedinger, at the Dirac equation, so you are a bit behind with the program :p
- ianai 8y agoThe particle, added forces, and things like “color”, spin, etc all always seemed ad hoc at best - and downright unscientific potentially, to me as well. It feels like it’s the most statistically verified model precisely because it’s been moulded to data so closely.
- jcranmer 8y agoThat's why physicists came up with supersymmetry, to provide a simpler, more beautiful explanation than the Standard Model. Unfortunately, the experimental evidence seems to indicate that the simple, elegant theory does not do a good job of reflecting reality.
- empath75 8y agoParticles are ‘just’ perturbations in the underlying fields. If you understand field equations you should understand that.
- buvanshak 8y agoWhat is a field?
- dwaltrip 8y agoIt's a mathematical construct that is a core part of the theory physicists use to make highly accurate predictions about many of the low-level dynamics of reality. It seems to usually be visualized as 2d plane-like sheet that can oscillate, and those oscillations represent particles. In reality it should be 3d, but that is much harder to draw.
- buvanshak 8y agoSo if objects are just perturbation in a field, and field is a mathematical construct, just like the concept of a number, or a line or a circle, then isn't it meaning less to look for a start for the existence of a field, and hence the whole universe?
- boomboomsubban 8y agoNo, for a couple of reasons. It's a mathematical construct used to describe observed phenomena, the phenomena itself isn't necessarily that similar to the construct. Further, it may be a terrible description.
- posterboy 8y agoA sinus is a field, deductively reduced to lower dimensions, e.g. a slice cut of a sound wave. Waves on the sea form a wave field, figuratively, and it extends to the bottom of the sea. Whereas a quantum field is a consequence of the Schroedinger Wave equation positing that the potential to observe a particle is distributed in space. As far as I know that's purely virtual, because observation of the particle collapses the potential. The crux is, the observation is not exact; The location of the particle is a probability distribution over a field as well. So ... it's fields all the way down. I'm not an expert, just stipulating.
- Jeff_Brown 8y agoIntuitively, if you're in a field, you get pulled in a different direction and/or amount depending where you are[1]. Except the meaning of the vector "pulling" on you might not be displacement of position. At a disco, for instance, you could think of the light creating a field that pulls your hair through the space of colors. [1]Unless it's a constant field, in which case you'll feel the same pull no matter where you go.
- danbruc 8y agoParticles are ‘just’ perturbations in the underlying fields. No, particles are particles [1], those fields in quantum field theory are just mathematical tools to deal with many particle systems in a manifest local and unitary way. There might of course actually be fields in the real world, but we have no evidence for that and those fields would not be the fields that appear in quantum field theory. [1] Obviously not classical particles like tiny billiard balls.
- maxander 8y agoIf particles are “just” particles, how would you solve the problem of two objects without spatial extent (point masses) being infinitely unlikely to ever collide? Among other things. In treatments I’ve seen, this is always explained in terms of particles “actually” being fields.
- danbruc 8y agoThey are not classical particles, the uncertainty principle, for example, still spreads out the location. I don't really know how particle interactions work exactly, but I am pretty sure it is not perfect point particles having to hit each other exactly. I guess there is something like a interaction probability depending on the distance between the particles. I include a bit from an older comment I once made here with links to a lecture where this issue is pretty clearly addressed. Here is Nima Arkani-Hamed giving the Salam lectures 2012, a five day series on the state of fundamental physics. I marked [1] about 30 seconds where he is very clear about this. You can also start here [2] and watch about 10 minutes of this lecture where he quickly redevelops the ideas of quantum field theory. [1] https://www.youtube.com/watch?v=tnA7bh7dTqY&t=1669 https://www.youtube.com/watch?v=tnA7bh7dTqY&t=1669 [2] https://www.youtube.com/watch?v=tnA7bh7dTqY&t=370 https://www.youtube.com/watch?v=tnA7bh7dTqY&t=370
- andy-x 8y agoIf you understand Schrodinger equation then you probably understand what wave function is - it's just a field of some kind. In quantum theory everything comes in quanta, and the quantum of the field is what we call a particle.
- mhh__ 8y agoIf you understand Schrodinger's equation, then have a look at some Quantum Field Theory lectures.
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- juliangamble 8y agoMy physics teacher used to say: "Whenever physicists don't understand something - they invent a new particle"
- analog31 8y agoIndeed, it's been a pretty fruitful approach. Physicists propose new particles for a variety of reasons. Though they weren't fully recognized as "particles" at the time, gaps in the early periodic table could be thought of as missing particles in a sense. An apparent consistent failure of conservation laws in a collision experiment could be described as a "particle" if the failure has a quantitative regularity that's consistent with an un-detected particle. Particles can be proposed to identify a way that a new theory can be tested -- the Higgs and the graviton are in this category. Given a choice, physicists prefer to explore theories that can yield experimental predictions, and particle detection is an area where theories can be tested with decent sensitivity, albeit at some cost.
- leetbulb 8y agoI don't know much about particle physics, but this is a really nice way to think about "particles". Thank you!
- ezequiel-garzon 8y agoA very wise person (I wish I knew who) noted: “All models are wrong. Some models are useful.”
- hasseio 8y agoGeorge Box I believe.
- ezequiel-garzon 8y agoThank you! At the very least it looks like he started the expression: https://en.m.wikipedia.org/wiki/All_models_are_wrong https://en.m.wikipedia.org/wiki/All_models_are_wrong
- mchahn 8y ago> In its 15-year run, MiniBooNE has registered a few hundred more electron neutrinos than expected. Wow. How could this be significant? (Not arguing).
- twtw 8y agoThey were expecting to see about 1600 events, and instead they saw about 2000 events. The significance of the excess in miniboone is therefore around 4.5 sigma.
- Tloewald 8y agoPresumably this is quite large relative to the expected number. I couldn’t find a statement as to what the expected number was.
- dwaltrip 8y agoNeutrinos hardly interact with normal matter at all, so we detect them in much, much lower quantities than other particles.
- njarboe 8y agoNeutrinos almost never interact with matter. The closet supernova in recent history[1] was detected via neutrinos with 11 observed. I can't imagine the number of photons from that event that would have hit a similar sized detector on the earths surface. [1]https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.58.1490 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.58...
- frumiousirc 8y agoKnowing the relative energy carried away from the supernova by photons and by neutrinos (1:100), photon and neutrino energy spectra, neutrino cross section and the size of the IMB and Kamiokande detectors you can estimate the flux of photons through some hypothetical light detector (sometimes called a "telescope"). Probably some model for interstellar gas is needed to account for scatter or absorb the photons.
- yummypaint 8y agoDespite how little neutrinos interact with matter, my understanding is that much of the pressure that actually drives a supernova explosion is caused by them. Their mean free path in lead is about a light year, so imagine how many neutrinos must be produced in a supernova. Now remember that we only detected 11 of them here on Earth using detectors that are massive on a human scale. Space is huge.
- prakster 8y agoWonder what will it take for Deepak Chopra to stop his quantum psychobabble. Even this didn't do it: https://www.youtube.com/watch?v=tZXewVWUKAM https://www.youtube.com/watch?v=tZXewVWUKAM
- nixpulvis 8y agoOh god, watching that made me lose all faith in both sides. Maybe this is why he's so obsessed with the circle ;)
- cozzyd 8y agohttps://arxiv.org/abs/1805.12028 https://arxiv.org/abs/1805.12028 is the arxiv link.
- acqq 8y agoI like this comment (with the nice explanation of the experiment): http://www.science20.com/tommaso_dorigo/miniboone_confirms_neutrino_anomaly-232739 http://www.science20.com/tommaso_dorigo/miniboone_confirms_n... Author's take: "The simple collecting more data and making the result stronger from a statistical standpoint in these cases does not help convince your peer: as I said, this is systematic in nature, so the problem has to be attacked by other means." On one side he is "an experimental particle physicist who works for the INFN at the University of Padova, and collaborates with the CMS experiment at the CERN LHC" but also writes "I am not a true expert in these matters so my comments would probably be deceiving or plain fallacious." For him, it seems there is still a need for some other kind of approach before something more specific than "the apparent excess was consistently measured through the years" can be claimed.
- ogennadi 8y ago> The persistence of the neutrino anomaly is extremely exciting, said the physicist Scott Dodelson of Carnegie Mellon University. > The existence of a sterile neutrino would revolutionize physics from the smallest to the largest scales. It would finally break the Standard Model of particle physics that has reigned since the 1970s.