Recent content by qraal

Yes, your instincts are wrong. The star is pulled by the sail's gravity as much as the sail is "anchored" by the star's gravity. Action=Reaction. The net momentum gain is from photons leaving the system asymmetrically, thanks to the huge mirror.

Shades of Velikovsky would invoke electrostatic forces rather than plain old Keplerian orbital evolution. He didn't "believe" in gravity.

Venus has over ~2 bars of nitrogen so that was already known. The surprise was that N2 is more abundant above the clouds than below. The prevailing assumption was that it was well-mixed, but the new data suggests the two layers don't mix well. So it's not new evidence for a Cataclysm - there's...

Ok, there are several issues with your understanding of the engulfment of the Earth/Moon system. However the original statement you were reading was merely hypothetical and in now way indicative of options for the far future. But back to my first statement. Firstly, the Sun will NOT passively...

Very high? They can be modeled as n=1.5 Polytropes, which means their central density is ~6 times their average density. In solar units a brown dwarf's radius is roughly its mass i.e. a 0.07 Solar mass brown dwarf would have a radius of ~0.07 solar radii. So it'd roughly have a central density...

Hi Red Dwarf Stars are fully convective, so 'heavy elements' are mixed evenly. Brown dwarfs... it's harder to tell. If sorting by atomic mass was the only thing happening, then maybe there'd be a core of the z fraction. But there's a lot of heat production and heat flow happening, so a core is...

The heliopause oscillates depending on the magnetic pressure of the Sun's solar wind and the ram pressure of the interstellar medium. Planet 9's magnetic field might have some influence, but otherwise it's a tiny blip compared to the immensity of the Sun's magnetosphere. Planet 9 still gets far...

That's not very helpful mathman, or very informed. The Inner Oort Cloud possibly includes the Sednoids (i.e. objects like Sedna), depending on the model chosen. Planet 9 presumably sculpts the Inner Oort Cloud via its gravity, as its existence is inferred from its effect on the Sednoids. Planet...

Both "species" have distinctive anatomical features in their teeth and skulls which are a bit harder to explain unless you're a physical anthropologist. Even the anthropologists argue over some of the fossils and usually they rely on the context of the fossils to make a judgement - Neanderthals...

You've answered your own question - "constant temperature". Inside the Earth, for example, there's a continual heat-flux from the core to the cosmic heat-sink. Any part of the Earth at "constant temperature" is only so because of that constant flux.

Maximising power-transfer efficiency within a normal sized house.

I'm tempted to say not really enough information. The statement "a sudden explosion" doesn't really explain whether there's additional energy added via the explosion. But the volume of gas is expanding into a background at constant pressure. Thus the volume change works against the background...

A gravity wave is a propagating change in a gravitational field, thus constrained to travel at c, away from the source system - a pair of orbitting pulsars, for example. A warp-bubble would be a moving source of space-time distortion - thus able to travel faster than light because there's no...

Limits of Organic Life The National Academy of Science produced this book about 6 years ago, which discusses the issues of alternative atmospheres: The Limits of Organic Life in Planetary Systems Also there's this paper by Johnson Haas which discusses a biosphere based on halides as the...

It's not the particle interactions, but the biological outcomes of such high energy particles passing through living tissue. We try to extrapolate from our experiences with lower energy radiation, but that's not really sufficient to the task. Hard data is needed. The exposure is episodic, so the...