Posts by HDE 226868
I've had a number of interesting conversations with people about how the cosmic microwave background (CMB) will evolve in the future. The CMB is the sea of photons left over from the epoch of recom...
Neutrinos have extremely low masses, and it's quite easy for them to reach high energies and speeds. As such, it almost always makes sense to treat a neutrino as being relativistic. I've been doing...
The shell variant of a Dyson sphere consists of an artificially-made shell of material about 1 AU in radius encircling a star. The sphere captures most of the star's energy and stores it for future...
One way to achieve this would be to simply change the structure of Earth's magnetic field. At the moment, the field is that of a large magnetic dipole, with the field produced by the motion of flui...
Before launching the site, we had a discussion on Codidact Meta about naming the category we currently called "Researched Q&A". Other possibilities we explored included "Hard science", our sta...
[science-based] almost certainly should be removed - I think we can safely assume that a site called Speculative Science is going to require science-based answers across the board. If an post's not...
I was the mod who deleted the comment - thanks for bringing this up. The main reason I deleted it was that I figured that the comment was primarily for the benefit of the poster, rather than the co...
Yeah, that's my fault. I wrote up an answer and posted it, but I deleted it shortly afterwards (and later undeleted it . . . and then redeleted it). I did so because I've been extremely active on S...
The Earth would be broken into pieces if the total energy delivered by the impacts was comparable to the gravitational binding energy of the planet. Earth is a sphere, so its binding energy is $$U=...
The known charge-conserving decay modes of free neutrons all involve the production of a proton, an electron and an electron antineutrino: $$n\to p^++e^-+\bar{\nu}_{e}$$ This beta decay is why, out...
The behavior of strange matter is not well understood - least of all under the conditions we're used to on Earth! Most theoretical treatments focus on places in which strange matter is likely to be...
Cox & Loeb 2008 performed one of the few simulations of the Milky Way/Andromeda collision of which I'm aware. It's not particularly easy to simulate a galactic merger, so the lack of detailed n...
Yes, if the orbit isn't circular. Seasons can definitely occur on a tidally locked planet. Just like normal planets, tidally-locked planets don't need to have perfectly circular orbits. This mean...
Often, when I'm building a world, I want to start out by determining some of its key properties. Maybe I'm trying to calculate a habitable zone, or figure out how long a year would be on a particul...
In most quantum field theories$^{\dagger}$, we have a quantity called the Lagrangian, from which we can derive information about the behavior of our system. It consists of a number of terms represe...
To accurately answer your question, you might need to use a stellar evolution code, either doing your own modeling or looking up existing data tables. I'd recommend the MESA code for the former app...
TL;DR You'll see the development of both aerial vehicles and the means to survive in harsh spaces. Technology will develope faster in this world - at least, technology related to this mountain. A...
As I'm sure you know, four more exoplanets were recently discovered around TRAPPIST-1 (Gillon et al. (2017)), bringing the total to seven "” all, amazingly, presumably rocky and near the star's hab...
The Milky Way and Andromeda will collide a few billion years in the future. Stellar collisions will be rare because - as Douglas Adams put it - "Space is big. Really, really big." In the galactic d...
A young B-type star (with a mass of about 10 M$_{\odot}$) is surrounded by a debris disk extending from about 2 AU to 1000 AU away. The disk has a mass of about 300 Earth masses - enough to form qu...
Yes, it can. We can determine the distance to the source if we have an idea of what's causing that shift in velocity. Let's say that we have a source moving at a speed $v$ away from us. If it emit...
Question requirements I think it definitely falls on the asker to demonstrate first and foremost that the basic tenets of their idea are feasible. Their question should show that they've done a go...
My civilization is planning to being starlifting, mining a star by heating up portions of its surface and using a powerful magnetic field to channel the matter away from the star and into storage u...
In reality, if you want to build a star, you need to specify a mass and a chemical composition, and then use the equations of stellar structure. This requires some numerical integration, and it's f...
In a class discussion last week, someone pointed out that a typical core collapse supernova releases $\sim10^{46}\text{ J}$ of energy in the form of (anti-)neutrinos while only radiating $\sim10^{4...
