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location Greece
age 74
visits member for 3 years, 8 months
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Retired experimental particle physicist.

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


Sep
19
comment Armageddon prevention
@DavidHammen you seem to have numbers "the energy needed to turn an impact into a miss exceeds the yearly energy consumption by all of humanity" Do you have a link? I am thinking in terms of changing the asteroid's orbit by sending a rocket with a robot device which will attach the rocket itself on the asteroid perpendicular to the orbit and keep kicking to change it. Not an explosion. Turn it into a rocket.
Sep
19
answered How are theories in physics validated against existing knowledge in practice?
Sep
19
comment Is the Standard Model consistent (UV complete)?
I suppose with your first sentence you are implying that the consistent perturbative expansions are not all the possible perturbative expansions from the model: that a subspace is only covered by the consistent ones.Otherwise I cannot imaging how an expansion of a function would not represent the function if it is well behaved. ?
Sep
19
comment Momentum of electron problem
You should be using relativistic kinematics, the total energy of the electron is not its kinetic energy only en.wikipedia.org/wiki/…
Sep
18
comment Why do roads appear wet on hot days? I do not understand
No, the density fluctuations are there but the refraction index is such that the angles of total reflection ( which are essentially what one gets at interfaces) are larger than the angle from the vertical your eye subtends when you get closer.
Sep
18
comment Is antimatter power theoretically possible?
There are no free floating positrons. They have been created as electron positron pairs at some point in their life line. Thus energy conservation says that you can never have "leftover power to spare" . The best you could have would be a technologically hard to create "battery", i.e. energy storage device.
Sep
18
comment Why do roads appear wet on hot days? I do not understand
If the road were a mirror, you would see an image of the sky on the road. The density changes of air due to temperature changes refract the light coming form objects in such a way that an image appears as if there were a reflecting surface, like water on the road. It is a refractive interface that geometrically creates similar optical distortions.
Sep
18
answered Why do roads appear wet on hot days? I do not understand
Sep
18
answered What theory unifies the electroweak and the strong forces?
Sep
18
answered Does a normal torch emit entangled photons?
Sep
18
comment Detecting negative energy products in particle accelerators
For neutral particles it is energy and momentum balances that work. There is no indication of tachyons, and to set up expensive experiments, for example to see if after the interaction vertex there was a vertex ( talking of neutrals) that started microseconds before the main vertex, is not justified by existing observations where the standard model explains 100% of observations at that level.
Sep
18
comment Detecting negative energy products in particle accelerators
All charged track particles detected in experiments up to now, cannot be tachyons, because the ionization loss, which is used to identify the mass would be inconsistent. If the particle appeared before the interaction going into the interaction region the curves in the magnetic field would not be as consistent as we have measured them. Take an electron which is the smallest mass charged particle, compadre.org/informal/features/featureSummary.cfm?FID=302 it would be starting from the end point towards the interaction and the path could not be this simple helix.
Sep
18
comment Detecting negative energy products in particle accelerators
yes. another search would be finding correlations with signals coming before the main interaction. An experiment early on with cosmic rays to find tachyons would depend on this time discrepancy detection. armaghplanet.com/blog/what-ever-happened-to-tachyons.html
Sep
17
comment Is there a reason why the spin of particles is integer or half integer instead of even and odd?
I think the answer by Siva shows that there will be a problem, half integer spins have different behaviors than integer ones, and these different behaviors have given us the Pauli exclusion and the statistics. The statistics does not depend on hbar as far as I know. all integer ones are bosons, i.e. no pauli exclusion.
Sep
17
answered Are double-slit patterns really due to wave-like interference?
Sep
17
comment Are double-slit patterns really due to wave-like interference?
Sorry, -1, but photons interact extremely weakly with each other. They may be coherent or incoherent, but they do not interact even in real time let alone in science fiction time.
Sep
17
comment Is there a reason why the spin of particles is integer or half integer instead of even and odd?
what about the different statistics exhibited by spin 1/2? and the Pauli exclusion? If all were integers all would have to follow bose-einstein statistics and no atoms could form. The spinors are crucial.
Sep
17
comment Detecting negative energy products in particle accelerators
tachyon production would disturb the momentum and energy consrvation rules obeyed in the models that fit the data, but a model of how this would happen is needed. Your "negative energy" could come from something like a tachyon.
Sep
17
comment About the Large Hadron Collider
more or less. New methods of acceleration may come up, which might make much cheaper accelerators, and new methods of detection too might appear, but it is not a fast process.
Sep
17
comment Detecting negative energy products in particle accelerators
etc assumptions entering our calculations. The whole system is consistent and the data agree with it. You have to have a specific mathematical model/theory of how a tachyon would interact with the matter in the electromagnetic caloremeter, which you have to develop. A monte carlo can only give out what is entered in its parameters and functions. i.e. you need a modified monte carlo.hep.phy.cam.ac.uk/theory/webber/WebberTopInst09.pdf they are very complex programs and need a lot of time for study before changing basic generators.