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Retired experimental particle physicist.

The picture is a fayum . It looks like aunts and cousins of mine :).


Apr
1
revised How are anti-matter atoms created?
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Apr
1
answered How are anti-matter atoms created?
Apr
1
awarded  Revival
Apr
1
revised Entropy in biological systems
added 132 characters in body
Apr
1
answered Entropy in biological systems
Mar
31
comment How exactly do protons and electrons interact with each other?
In quantum mechanics one no longer talks of "attraction" since the possible positions and energy levels are quantized, not continuous as in classical attractive force physics. The potential is the 1/r potential of electricity but the solutions are the energy levels and two electrons with different spins can be at the same level, and also electrons can be caught at higher energy levels.
Mar
31
comment How exactly do protons and electrons interact with each other?
look at the energy levels of the hydrogen atom hyperphysics.phy-astr.gsu.edu/hbase/hyde.html#c2 . If an electron with the appropriate energy is caught at the lowest n=1 level has two spin states so two electrons can be there. the atom is neutral with one,but the other energy level exists and can catch a second electron if it has the correct energy or if it releases part of its energy in a photon. The electron(s) are in orbitals around the nucleus, i.e. probability distributions in space hyperphysics.phy-astr.gsu.edu/hbase/chemical/eleorb.html
Mar
31
comment How exactly do protons and electrons interact with each other?
It might also be caught into a hydrogen anion en.wikipedia.org/wiki/Hydrogen_anion , if it has the appropriate energy as it scatters.
Mar
31
comment Does Light Ever Cease Once Created
Yes, nothing to scatter on it will go on forever, or as long as the universe lasts according to reasonable models for the universe. There exist cyclic models en.wikipedia.org/wiki/Oscillating_universe , and there in the "big crunch" there will surely be density enough for any original photons to be absorbed.
Mar
31
answered Does Light Ever Cease Once Created
Mar
31
comment Does inflation predict a multiverse?
the recent BICEP2 results which show an imprint of gravitational waves and quantum fluctuations imply that the graviton is there. How can here be quantum fluctuations without a graviton?
Mar
31
comment Why is an electron still an elementary particle after absorbing / emitting a photon?
One should note that exists no conservation law for the number of photons the way there exists one for the number of electrons (no "photon number conservation" as "lepton number conservation" )
Mar
31
comment What happens when a photon hits a beamsplitter?
@daaxix Looks fine as long as you keep in mind that the wavefunction square describes probability distributions ( i.e. the photon is whole it is the probability that has wave properties in QM )
Mar
30
comment What happens when a photon hits a beamsplitter?
look a the answer by StickyCube . A photon is an elementary particle as much as an electron. It has a probability of going left or right in a splitter and a corresponding probability to line up in spin in such a way that the ensemble displays polarization; this for example is a reference I found in a similar question here of how one could have a wavefunction for a photon onlinelibrary.wiley.com/doi/10.1029/JB078i017p03356/…
Mar
30
comment Sun's tidal force on Earth
Tides lift up the earth at the same time as water. They are called earth tides en.wikipedia.org/wiki/Earth_tide . It lifts the ground about 40 cm . It might trigger earthquakes nat-hazards-earth-syst-sci.net/12/587/2012/… or eruptions onlinelibrary.wiley.com/doi/10.1029/JB078i017p03356/…
Mar
30
answered Could there be massive gravitons and in our spacetime?
Mar
30
comment Sun's tidal force on Earth
have you read en.wikipedia.org/wiki/Tide
Mar
30
comment What happens when a photon hits a beamsplitter?
If you really want to see how the classical electromagnetic wave emerges from the ensemble of photons you need some background in quantum field theory and its mathematics. Here is a link that shows this motls.blogspot.com/2011/11/… the photons add up coherently to build up the phases . for visualization, think of a wave of people , as in a stadium. You could split the wave, but this would mean re-directing the phases of movement of individual people. People would not be split
Mar
30
comment Is it possible to project a magnetic field at a location in space?
@Phil you could use the power of the electric field as described above to create a small electromagnet, no?
Mar
29
answered Where does a string tighten when you pull it?