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7164327
bio website motls.blogspot.com
location Czech Republic
age 41
visits member for 4 years, 4 months
seen 9 hours ago

Hi, I am a string theorist and a publicist.


May
10
reviewed Approve What gauge is used in the Lagrangian for a non-relativistic point particle in an electromagnetic potential
May
10
revised What gauge is used in the Lagrangian for a non-relativistic point particle in an electromagnetic potential
added 28 characters in body; added 396 characters in body
May
10
answered What gauge is used in the Lagrangian for a non-relativistic point particle in an electromagnetic potential
May
10
reviewed Approve How many digits of Pi are required in physics?
May
10
answered Is it pions or gluons that mediate the strong force between nucleons?
May
10
comment Protons' repulsion within a nucleus
I've edited the question, assuming that I understand Abdullah's good point.
May
10
revised Protons' repulsion within a nucleus
added 91 characters in body; edited title; added 24 characters in body
May
10
answered Protons' repulsion within a nucleus
May
10
answered cm^3/g as a unit of adsorption
May
10
comment 7 GeV dark matter particle: how particle accelerators missed it?
The baryons have annihilated against antibaryons, so that 1 billion and one of the former and 1 billion of the latter led to 1 baryon only. Similarly dark matter must be able to annihilate at a not-too-vastly-lower rate so that it's reduced to the current density - otherwise it could be predicted billions of times denser than what is observed. This is a nontrivial constraint - a lower bound on some cross sections - which is not based on accelerator experiments but it doesn't mean that it may be ignored.
May
10
comment 7 GeV dark matter particle: how particle accelerators missed it?
Dear Anna, you don't need a "theory of everything" to answer these questions, so you shouldn't be using a "theory of everything" in a derogatory way as an excuse that you haven't answered the key question so far. The density of the dark matter particles at their characteristic era of the Big Bang evolution is just given thermally and the later evolution of the density is dictated by the Big Bang solution and a few cross sections.
May
10
answered equivalence principle and nontrivial compactifications
May
9
reviewed Approve Weyl exponential form of the Canonical Commutation Relations
May
9
reviewed Approve Theories that Relate Gravity, Electricity, and Magnetism
May
9
comment 7 GeV dark matter particle: how particle accelerators missed it?
Dear Anna, good but if dark matter only interacts gravitationally, it won't have enough time since the Big Bang to dilute its density to the acceptable value we measure today, will it? There must be a large enough annihilation cross section for it, right?
May
9
comment 7 GeV dark matter particle: how particle accelerators missed it?
Nice question, lurscher, and good answer, Jerry - but can you write some numbers how often one creates a photino etc. and what the cross sections would be for LEP for a model that explains it? And isn't a sufficient cross section required for the particle's abundance in the Universe to drop to the 23 percent of the dark energy we have today?
May
9
comment Correlation between outstanding hints in experimental particle physics
It's good but doesn't it explain just one of the bumps?
May
9
asked Correlation between outstanding hints in experimental particle physics
May
9
comment What do ants see?
Dear @Peter, you're surely right, the main dynamics behind the average quality's downtrend is that people in physical love with physics are not asking many questions. Of course, I guess that a part of their reason is that they don't expect that they will get useful answers. This expectation is also governed by the downtrend, so it is not true that the causation only goes in one direction as you suggest. The characteristic quality of some questions and behavior always helps to shape the environment and smart people at a certain level quietly disappear from a website that becomes too silly.
May
9
comment Anti-laser: How sure we are that energy is transported?
Some additional references and comments about anti-laser were discussed later here: physics.stackexchange.com/questions/9628/…