109,111 reputation
4166295
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 9 months
seen 5 hours ago

Semi retired old time computer nerd who started programming on a Commodore Pet.

Since I'm also active in the Physics forum I should add that I started as a theoretical chemist, moved into solid state photochemistry and finally worked in industry as a colloid scientist. I only became a full time computer nerd in 1997.


Oct
19
comment Metal with the biggest positive and negative charge per atom (ion)
This is really a chemistry question. In the physical world we can make arbitrarily highly charged ions e.g. gold nuclei, Au$^{79+}$, are made at the RHIC.
Oct
19
comment Loop quantum gravity- is the critical density sufficient to form a 'black hole'?
Yes. If you want to understand this I'm afraid you'll have to get stuck in and learn about the FLRW metric. Without knowing your background I'm not sure what to recommend as a starting point. The Wikipedia article is not suitable for beginners. Incidentally your other question also stems from misunderstanding the FLRW metric.
Oct
19
comment Loop quantum gravity- is the critical density sufficient to form a 'black hole'?
A finite, i.e. closed, Friedmann universe is homogeneous and isotropic just like flat and open Friedmann universes. In the real universe at the current time the matter distribution is obviously not isotropic and locally black holes and their associated horizons can form. However if you look at the CMB (that dates from the recombination era) the universe was homogeneous to about one part in $10^5$. Because inhomogeneities grow with time we expect that near the Big Bang any conceivable universes would be almost exactly homogeneous.
Oct
19
comment Loop quantum gravity- is the critical density sufficient to form a 'black hole'?
The universe is described by the FLRW metric. This has a singularity at $t = 0$ (and for closed universes also at the recollapse time) however it has no horizons. A black hole is described by the Schwarzschild metric. This has a singularity at $r = 0$ and a horizon at $r = 2GM/c^2$.
Oct
19
comment Loop quantum gravity- is the critical density sufficient to form a 'black hole'?
No, because the matter distribution in the universe is (approximately) homogeneous so the gravitational potential is the same everywhere. There is simply no concept of a Schwarzschild radius in these circumstances.
Oct
19
comment Can a Storm make the day longer/shorter?
You need to estimate the angular momentum of the jet stream and compare it with the angular momentum of the Earth. I haven't done the calculation, but I'd be surprised if the effect was measurable.
Oct
19
reviewed No Action Needed Normal force of loop-the-loop at the side of the circle
Oct
19
reviewed Close How to calcuate uniform circular motion?
Oct
19
comment Loop quantum gravity- is the critical density sufficient to form a 'black hole'?
The universe is not described by the Schwarzschild metric so it has no Schwarzschild radius.
Oct
18
comment While finding escape velocity, does human mass counts as the mass of Earth?
@FranciscoPresencia: the mass change due to absorption or emission of radiation is negligible.
Oct
18
reviewed Looks OK Why the current decreases with increase in voltage in transmission lines? But according to Ohm's law current should increase with Voltage
Oct
18
reviewed Leave Open Self-replication of gravitons in string theory
Oct
18
reviewed Leave Open Doesn't the second postulate of special relativity imply the existence of “luminiferous ether”?
Oct
18
awarded  Good Answer
Oct
18
comment Building blocks of particles in different theories
No. The concept is specific to quantum fields. The motion of planets is described by a classical field and this is completely different.
Oct
18
comment Building blocks of particles in different theories
You'll have to clarify what excitation at the macro-scale means.
Oct
18
comment Building blocks of particles in different theories
The idea of a particle as an infinitesimally small dot is not a good description. Particles are described as excitations in a quantum field. They are point like in the sense that by going to arbitrarily high energies the particle can be resolved with arbitrarily great precision, but this does not mean quantum field theory models them as points.
Oct
18
comment Self-replication of gravitons in string theory
The phrase self-replication was used by the IO9.com journalist not by Luboš. It is not a term used by physicists.
Oct
18
comment Self-replication of gravitons in string theory
I don't think the phrase self-replication has any special meaning in physics. Are you asking how string theory removes the divergences when summing the Feynmann diagrams for gravitons?
Oct
18
reviewed Reject suggested edit on Is the universe finite or infinite?