40,234 reputation
22476
bio website
location Greece
age 74
visits member for 3 years, 3 months
seen 41 mins ago

Retired experimental particle physicist.

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


Sep
13
comment Why is the tunnel effect of solid matter not observable in macroscopic objects?
@user56771 It will depend on the setup, imo
Sep
11
answered Could Quark model turn out to be false?
Sep
10
comment Why does letting air into a box of wine help the flow?
You get the same effect with portable water coolers:if air is not allowed to enter the water stops flowing after a while, the air pressure balances the weight of water+low-pressure-air left in the cooler.
Sep
10
comment Why does letting air into a box of wine help the flow?
This is correct, but it seems to me the questioner has no idea of how a vacuum can be created using the balance of air pressure and weight of fluid, as in the Toricelli barometer. en.wikipedia.org/wiki/Evangelista_Torricelli.
Sep
10
answered why aren't there nuclear powered aircraft?
Sep
7
answered Why isn't heavy water much heavier, and what use is it for fission reactions?
Sep
7
answered Is it possible to describe the entire universe with the behavior of an $\mathbb{R}^n$ field?
Sep
7
answered What do we actually mean when we say that matter is a wave?
Sep
5
comment A large rock falls on your toe. Which concept is most important in determining how much it hurts?
Pain is a biological attribute and inappropriate for a physics question, since it depends on biophysical constants.
Sep
4
comment Is carbon dioxide a greenhouse gas?
@AlanSE When a feedback is positive then it will run away, it is an unstable situation ( think loudspeakers) until it hits some limit of course (the power available in loudspeakers), I believe in the models used by the IPCC no such restraints are introduced when they predict those huge catastrophic numbers of sea rise and temperature rise, which by the way have not materialized yet, when one looks at the ten year old predictions.
Sep
4
comment Why is the Heisenberg uncertainty principle stated the way it is?
I have given an example down to the bare basics of HUP. One particle, no statistics, in a magnetic field. Its circle can be predicted by construction with accuracy. The HUP says that that I cannot see in a detector a more accurate position than it (the HUP) allows, this means that the position I find will deviate from the predicted circle within HUP. I mean that it will be equally probable for the measured point to deviate at the edge of HUP as at the center of the interval. I wonder if anyone has done the experiment.
Sep
4
comment Why is the Heisenberg uncertainty principle stated the way it is?
@DavidZaslavsky and do you think it has a gaussian distribution, as it would if it were a real sigma? Or is it an interval of undefined values for that variable? I am afraid that this is how the thinking about underlying classical explanations of QM start.
Sep
4
comment Is carbon dioxide a greenhouse gas?
This intro to the "greenhouse effect" seems fairly good : bouman.chem.georgetown.edu/S02/lect23/… .
Sep
4
answered Is carbon dioxide a greenhouse gas?
Sep
4
comment Extract energy from magnets
Heating a magnetized bar demagnetizes it, it shows it is in a lower energy state than the ambient temperature . It can only gain energy and be destroyed not give energy.
Sep
4
comment Why is the Heisenberg uncertainty principle stated the way it is?
@DavidZaslavsky My point is that when you call it a standard deviation people start looking at classical statistics, which defeats the point . It is not classical statistics that defines the delta but the commutators.
Sep
3
revised Why is the Heisenberg uncertainty principle stated the way it is?
added 35 characters in body
Sep
3
answered Why is the Heisenberg uncertainty principle stated the way it is?
Sep
3
answered How often does a cosmic ray hit our eyes when we are on Earth?
Sep
3
comment Why is a nucleus isotropic?
But Ron, all this is fine and good as an introduction to scattering in the S matrix format, but how about experimental evidence (which I linked in my answer) that shows non isotropy in theta due to nuclear resonances? It would have been isotropic if there were no further interactions open to the scatter which the experiment demonstrates. It is not isotropic in the real world!