Recent content by Al_

Yes, Xenon has been used medically for surgery. I don't know if Moon rocks emit Xenon particularly , but I think its likely they emit some gases. Based on Earth rocks, and science done about other planets.

I did some rough calculations based on the Barometric Formula (https://en.wikipedia.org/wiki/Barometric_formula) to find out how deep a chasm would need to be, on the Moon, to have a Earth-like atmosphere at the bottom. I used 0.3 nPa and 1/6 Earth gravity, and assumed a constant temperature all...

that's quite a tense atmosphere!

Getting back to the first point, wouldn't it be amazing fun to discover a proof that Fermat could have found using the tools he knew? He had a good reputation at the time, and it would have been out of character for him to claim to have a proof that he did not have. Maybe there is a proof out...

How powerful could this be at it's strongest, say, a supermassive black hole merger lensed by another nearby black hole? Could the waves be powerful enough to be easily detected, or even to be seen directly if a human was there? What would they do to solid matter, bend or crack it?

When chlorophyll first evolved the atmosphere was methane, CO2 etc. Did green light get through?

The main effect on everyday life is we won't be thinking about how we can find the EoS for a neutron star.

Heard talk about He3 on the Moon and launching a fusion rocket. Is this all just a mashup of Sci-fi ideas?

Fission fragment rockets are much more realistic at the moment. And very cool.

yes, but that was lifting a much larger mass, and it was fighting air pressure in front of the rocket, and it throttled back part way through to avoid too much friction

Hmm. Maybe, this isn't such a crazy idea, if... Bear with me. The tube slopes upward and ends at a high altitude where the air poses little frictional resistance, say 10km. There is a cover over the top end preventing the thin air entering. At ground level, it is also sealed by a door, and large...

You mention "[SIZE=16px][FONT=noto sans]radial velocity" - so, did the video mean to say "radial momentum"? In a simple system of one star and one planet, would they have equal radial momentum around their shared centre of mass?

To enable[SIZE=16px][FONT=noto sans] the fission fragments to escape, yet allowing a critical mass, there could be multiple small sub-cores each with its own magnetic coils, which exchange neutrons to achieve criticality as a group. The obvious place for control rods is then between the sub-cores.

In that reactivity link I found a mention of submarine reactors that use a high proportion of U235. Wikipedia states: "many designs use highly enriched uranium but incorporate burnable neutron poison in the fuel rods. This allows the reactor to be constructed with an excess of fissionable...

The NASA study quoted above uses a dusty plasma, and has two designs, one with a critical mass of Pu, and one with U238. In both, the moderator reflects back neutrons to achieve criticality. With no moderator, the mass of fuel would need to be greater, but I don't think it would need to be...