Recent content by phyzguy

What does settling Mars have to do with space habitats?

You're being too planet-centric. The future of space exploration is living in space habitats that we construct. Try reading, "The High Frontier" by Gerard O'Neill. We can build structures in space that will be very pleasant places to live.

There have been discussions here of genetic and cultural drift. If we (or some other race) were to colonize the galaxy, it would take millions of years. Evolutionary changes and cultural drift would be inevitable. This isn't necessarily a bad thing.

(1) Generation ships need not be "horribly inhumane". A space habitat hundreds of meters in diameter could be quite a pleasant place to live. Add a fusion drive (which we don't know how to build today, but likely will in a century or so) and you could reach Alpha Centauri in a few hundred...

I think the Fermi paradox is different than what has been stated here. I think it goes like this: (1) We can already envision our species spreading through the galaxy. With technology that we know, we could reach nearby stars in a generation ship in a few hundred years. Once there, we could...

The thing to remember is that, if new life formed today on Earth, it would get eaten very quickly. So you can't conclude that life only formed once on Earth.

The solution for the magnetic field of an arbitrary distribution of currents is well known. The attached summary is from the Feynman Lectures on Physics, Chapter II-21. So if you know an arbitrary distribution of currents J(x,y,z,t), you calculate the integral for A, than take curl(A) to get B.

Basically all large galaxies have super-massive black holes in the center. It's thought that the galaxy and black hole grow up together. Our own is call Sagittarius-A* and it weighs more than 4,000,000 times the mass of the sun. https://en.wikipedia.org/wiki/Sagittarius_A*

It's a story. Just say there was a breakthrough in high strength materials that made the space elevator possible.

If you're going to launch a rocket to even 10 km, you're potentially going to cross paths of commercial aircraft. I suspect that the last thing you want to do is shoot down a commercial aircraft and kill several hundred people.

AAS (the American Astronomical Society) has a free introductory astronomy textbook available online at the link below. If, after reading about the topics you listed, you still have questions, please come back and ask. https://aas.org/posts/news/2021/09/astronomy-free-online-astro-101-textbook

And yet still no punctuation nor capitalization of the second sentence.

Polaris is "up" from the north pole. North is a direction along the surface of the Earth.

One possibility, known as the Hartle-Hawking no boundary proposal, is that if you go backward in time towards the big bang, you reach a point where space and time cease to exist. In this proposal, asking, "What was there before the big bang?" is similar to asking "What is north of the north...

It's called a sun dog: https://en.wikipedia.org/wiki/Sun_dog