108,918 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.


7h
comment Uncharged Gluon Representation
octett or octet?
14h
comment Discrepancy in introducing Schottky barrier
The bands aren't discontinuous because the junction isn't infinitely thin. The energy level varies continuously (but steeply) across the junction. The force on carriers is indeed very high, but it acts only over a very short distance. The force times distance is of course equal to the difference in the energy levels.
1d
comment Theory on what would happen if a proton touches anouther
It sounds as if you are proposing to create a gravitational attraction between the protons by bending spacetime around them. Presumably you'll then let the spacetime flatten out again and trap the energy created as the protons fly apart. The obvious first problem is that the process would require exotic matter, which as far as we know doesn't exist. The second problem is that we'd have to put energy in to warp spacetime. We'd get some of the energy out again when the spacetime flattened out, but we wouldn't get all the energy back. The difference would be the kinetic energy of the protons.
2d
comment Which moves faster in a time $t$: $A$ or $B$?
What you need to know to solve this is that the drag on a sphere is given by $F_d = \tfrac{1}{2}C_d \rho A v^2$, where $A$ is the cross sectional area $\pi r^2$ and $v$ is the velocity. $C_d$ is a constant and $\rho$ is the fluid density - neither of these depend on the size of the sphere.
2d
comment Is ohm's law violated in electric transmission lines?
It's the electrical potential at the generating station.
2d
comment Bubble pressure ascending?
Do you think the pressure inside the bubble will be greater than, less than or equal to the pressure of the water around the bubble?
2d
comment How to feed a small black hole against 1 TW Hawking radiation pressure?
Oops, I missed a factor of $1.602 \times 10^{19}$ :-)
2d
comment About time measurements
No, there's no suggestion that time isn't continuous. The illusion is that it flows. We wouldn't say that distance flows; it just is. The same argument applies to time. Do some Googling for block universe for more on this idea.
2d
comment About time measurements
The interval between two timelike separated points certainly isn't an illusion. The illusion is the human perception that time flows.
2d
comment How quickly was the Earth rotating 250 million years ago?
@DavidHammen: agreed - my reply was intended mostly to point out the error in the orginal question. The exact value for the rate of change of day length doesn't really matter, and I don't think a change of 2.3 vs 1.7 ms/century affects the conclusion that the Earth wasn't created in 4004BC.
Oct
19
comment Why can't we reach the ends of rainbow?
Rainbows are circles so they have no ends. They look semicircular because we can usually only see part of them.
Oct
19
comment What prevented the early universe to become a black hole before inflation?
My comments to that question address the classical GR theory not LQG.
Oct
19
comment What prevented the early universe to become a black hole before inflation?
I wonder if it's worth writing another blog type question and answer on this topic ...
Oct
19
comment What prevented the early universe to become a black hole before inflation?
Oops, drat! Try this link.
Oct
19
comment Metal with the biggest positive and negative charge per atom (ion)
Metal ions form the basis of charge storage (in electrical double layers) in supercapacitors. However I think these mostly use monovalent ions like Na$^+$.
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.