Recent content by nburns

How does the radiation from neutron stars compare to white dwarfs? Are neutron stars white? Which is brighter?

Does the same logic apply to magnetic fields of black holes?

Thanks for your answer. So you are saying that, basically, the gravitational field surrounding the black hole doesn't need to "communicate" (for lack of a better word) with the mass at its center as long as the field isn't changing?

Forgive me if this is a dumb question. If nothing gets out of a black hole, how does the gravity get out?

I think it's harder to understand the meaning of the curvature of space-time. My interpretation is that the curvature of space-time is more just a way of conceptualizing what the equations are saying than a literal description of reality. The equations are the only part of the theory that is...

If you're talking about manned spaceflight, then I'd expect the water losses to be slight, because most missions never left Earth orbit. The water would have fallen back into the atmosphere. The moon missions may have left some water on the moon, though.

I think I might see your point. If the gas is simply contracting under its own weight, there is no discrete change in phase. Actually, at some point the gas changes phase into plasma, but that change is endothermic. I'm trying to relate this to something familiar, like an Earth-bound cloud...

Yes, it isn't a phase change, but it sounds analogous to one from the standpoint of thermodynamics. The gas molecules would initially cool down, until they succumbed to gravitational attraction. Then they would heat up as they were compressed by gravity.

The US border control and police have a device that can accurately detect trace amounts of drugs by sampling the air, and signals detection with a visible change. The device is a dog.

It's been a while since I studied chemistry, but since no one answered, I'll throw my 2 cents. For #2: It's a fairly safe bet that the cyclopropane ring will open, leaving a temporary + on the quaternary carbon. There are two things that make this easier: the carbonyl oxygen can donate...

Wouldn't it be accurate to say that if you weigh 180 pounds on Earth, the Earth weighs 180 pounds on you?

That sounds analogous to a phase change. Ice formation is exothermic. It seems paradoxical, but it makes sense if you think about it. Water molecules want to stick together as ice, so when they finally slow down enough to stick, getting stuck releases heat.

I imagine that these photons (generated by either process) tend to get reabsorbed before they exit the cloud, so the edges cool faster than the center.

That's a geology question. When water enters the ground, it sinks until it reaches a layer of nonporous rock, at which point it's called groundwater. Groundwater slowly makes its way downhill through porous rocks and eventually it empties into the ocean.

If collapsing is like freezing, then you'd expect it to happen slowly: the collapsing gas would have to get rid of a lot of heat, which it would transfer to its surroundings, creating a negative feedback loop and acting as a brake.