How much tension between recent AMS-02 80 Gev dark matter and Lux-Xenon negative results?
Recent results ( Arxiv 1610.03840 and 1704.08258) suggest a WIMP dark matter particle near 80 Gev. See also https://phys.org/news/2017-05-possibility-cosmic-rays-due-dark.html
If this particle really...
It appears that Stuart Prager is “stepping down” as director of PPPL. I wish him well.
But in the announcement it refers to a “recent technical setback in the NSTX-U facility”.
I had not heard previously of this set...
Lepton Universality and Pauli Exclusion
Put in a possibly oversimplified way, lepton universality says that electrons, muons, and taus all behave in the same way except for mass effects. The question is “Does this apply to Pauli exclusion?”
Due to the Pauli exclusion principle, only two...
The earth's rotation acts as a clock and defines a rather precise unit of time called the day.
We could go out in outer space and spin a marble and get a reasonable clock.
On the other hand, it is my understanding that you can't do this with an electron,
that is, you can't start an electron...
What does and does not have intrinsic spin?
Wikipedia Spin (Physics)
“In quantummechanicsand particlephysics, spinis an intrinsic form of angularmomentumcarried by elementaryparticles, composite particles (hadrons), and...
Above is a link to a news story about the recent Tri Alpha Energy “breakthrough”.
It looks to me like a very nice development in increased stability of a proposed reactor design.
Does a Buckyball spin like an electron or like a baseball?
We are often told that an electron does not really spin like a baseball.
Only one (or two, if you count up and down) spin states, for example.
How about a Buckyball?
Does it spin more like an electron, or more like a baseball?
In my mind they are all the same.
But some serious physicists (Schlosshauer, for example) claim there is no evidence for the existence of collapse.
What about Lyman alpha emission, where an electron in a hydrogen atom “jumps” from level two to level one and emits a photon?
Passing light through a circular sieve:
Well, actually, let’s think about radar or microwaves with a wavelength of order a centimeter or two, so you can tailor your aperture, say by etching a silver screen on glass. If you have a reflective metal screen, and you cut a long narrow rectangle in...
National Geographic quoting Dr Hennawi, the lead author of the Science paper, says it is a ten million to one chance to find four quasars so close together. How much more unusual is it that in the first...
In the news today, several articles about Lockheed's ambitious five or ten year plan. eg this one from the Washington Post. http://www.washingtonpost.com/news/capital-business/wp/2014/10/15/nuclear-fusion-energy-in-a-decade-lockheed-martin-is-betting-on-it/ This one from Aviation Week...
India's thorium reactor delayed.
So another year delay, more or less.
Will it really start up next year?
I hope so.
It is thought that there are approximately 10^80 protons in the observable universe, but there are approximately 10^90 photons in the observable universe. If my googling is correct, there are also approximately 10^90 neutrinos in the observable universe, but their temperature is only 1.9 degrees...
In the context of the recent Fuzz or Fire workshop,
I would like to make a short argument that event horizons are irredeemably in conflict with unitarity:
An argument frequently mentioned in the Fuzz or Fire workshop is that by the...
Alice is transmitting an electromagnetic beam to Bob.
Assume it is a well collimated beam, like a laser beam, or a maser beam.
As Bob's distance from Alice increases, his signal strength decreases according to the well known inverse square law.
Eve, the eavesdropper, is beside the beam, not...
Are deBroglie waves transverse or longitudinal? Can they be polarized?
What about the deBroglie wave of a ground state neutral spin-zero Helium 4 atom?
What experimental evidence do we have that supports the detailed nature of a deBroglie wave?
I have always assumed that deBroglie waves...
Is it possible to split a single light beam into two beams of opposite circular polarization?
A properly oriented calcite crystal will separate a unpolarized beam into two beams, one vertically polarized and one horizontally polarized. Other polarizers pass just one polarization and absorb...
How do particle scattering cross sections scale with energy in colliders?
Particularly photons, electrons, protons, and gold or lead nucleii?
(If necessary, break this into four separate questions.)
It is stated that due to the Heisenberg uncertainty principle, it takes more energy to...
Pay with angular momentum instead of energy?
What do the experts here think of this recent paper?
In particular can you really change the spin or angular momentum without changing the energy?
Would this also apply to ordinary momentum?
(Note the authors say...
Recently the NIST group demonstrated a two qubit programmable quantum computer,
And another consortium used a two qubit computer in an iterative fashion to compute some properties of the hydrogen molecule.
How many qubits...
After we measure the position of a particle fairly sharply, it “spreads out” or the uncertainty grows according to the Heisenberg uncertainty principle. After we measure the polarization of a photon, does it spread out, too? If not, why not? If so, how fast?
Retrocausality solves QM problems??
Does retrocausality successfully solve the problems of QM?
This recent paper seems to claim it does.
Also what is the relationship of retrocausality and collapse?
Both string theory and loop quantum gravity claim possible elimination of the black hole singularities. If that is true, what do they predict the inside of a stellar size black hole contains? Is it some new ultra dense state of matter, or something else?
I will try to ask various...