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Posts by HDE 226868‭

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Rigorous Science How to "set" the lightsail?

First, let's look at the different types of trajectories a solar sail can take. They differ mainly based on something called the lightness number, $\beta$, which depends on the composition and stru...

posted 8y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science How does one calculate the tidal heating of a satellite?

Wikipedia gives the formula for the tidal heating $\dot{E}$ as $$\dot{E}=-\text{Im}(k_2)\frac{21}{2}\frac{R^5n^5e^2}{G}\tag{1}$$ where $R$ is the radius of the satellite, $n$ is something weird cal...

posted 8y ago by HDE 226868‭  ·  last activity 6y ago by HDE 226868‭

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Rigorous Science Natural subterranean cave formations on Mars

Apparently, this was investigated by NASA in the early 2000s in what became known as The Caves of Mars Project. Its goal was to find possible places for humans to live over extended periods of time...

posted 8y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science Could a carbon/silicon/oxygen planet exist?

Models of such planets exist, courtesy of Unterborn et al. (2014). They discuss planets of similar composition to yours - looking at the value of the mass fraction given by $(\text{Mg}+2\text{Si}+\...

posted 8y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science Is an interstellar clock orbitally possible?

Your main problem is that the planets will comprise a chaotic system. This is why the stability of the Solar System is so difficult (possibly impossible) to determine. Our best models are valid for...

posted 8y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science Can stars that are not powered by nuclear fusion exist?

Use a Quasi-star. The solution I think will finally work is to use a quasi-star, a theoretical object from the early universe consisting of a black hole of perhaps $10M_{\odot}\text{-}100M_{\odot}...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Rigorous Science With current technology, what would be the best way to store energy for future generations?

Flywheels The method[3]: Generate electricity normally. Use the electricity to accelerate a flywheel to very high speeds. Capture the kinetic energy of the flywheel when needed. The benefits ...

posted 9y ago by HDE 226868‭  ·  last activity 9y ago by HDE 226868‭

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Rigorous Science How Close Are These Two Planets?

Using Kepler's third law, I get $$a=\sqrt[3]{\frac{P^2G\times(M+M)}{4\pi^2}}=5.32\times10^4\text{ kilometers}$$ where $a$ is the semi-major axis, $P$ is the time it takes the planets to orbit each ...

posted 8y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science Starbuilding: What is lacking in the logic behind Cosmos 2 star system generation algorithm?

This is essentially a partial answer, insofar as it's a series of loosely chained together critiques. Sometime in the future, I'll revise it so it's more organized, but for now, it's a work in prog...

posted 8y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science How far could a planet be from its star and still be kept habitable by intense greenhouse gases?

I agree with Tim B's assessment that this is a complicated question. However, I disagree on just why this is the case. The characteristics of the star are well defined, given that it's a solar anal...

posted 8y ago by HDE 226868‭  ·  last activity 6y ago by HDE 226868‭

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Rigorous Science At what distance from these planets should this moon be placed?

Is it possible? Absolutely. Pluto and Charon are tidally locked, and yet Pluto has four other moons1. Charon is relatively massive in comparison to Pluto - about one twelfth its mass. Indeed, the c...

posted 9y ago by HDE 226868‭

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Rigorous Science How big a black hole is needed for this story?

I suppose I'll address the solar flares angle, since nobody appears to have tried that yet. My main objection here is that an external source will have a very hard time causing solar flares. Solar...

posted 9y ago by HDE 226868‭  ·  last activity 9y ago by HDE 226868‭

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Rigorous Science Close the door on your way out - Life lit by a blue dwarf star

Yes, it can happen. For this to be possible, you first have to put the planet far enough away that it can become totally icy. Then, after the temperature rises as the red dwarf transitions into a ...

posted 9y ago by HDE 226868‭  ·  last activity 9y ago by HDE 226868‭

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Rigorous Science Can you add a mini moon to Earth?

Note: If anyone can double-check my numbers and result at the end of this answer, that would be much appreciated. This looks like a question that can be broken down as per your bullet points, so I...

posted 9y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science How much energy would it take to ignite a brown dwarf?

$2.55\times10^{45}\text{ Joules}$. But it probably won't work. There are a few things we need to get straight here, namely, the differences between brown dwarfs and giant planets. Here are two of ...

posted 9y ago by HDE 226868‭  ·  last activity 9y ago by HDE 226868‭

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Rigorous Science Can stars that are not powered by nuclear fusion exist?

Note: This answer is not even close to being finished. I'm putting it out there as a sort of sanity-check, so I can get some input as to whether or not my idea is totally crazy or not. Links and mo...

posted 9y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science How large can a volcano be?

A key part of the plot in a story I'm working on revolves around the main region being on top of volcano that is set to erupt. The trouble is that the region in question in my setting is roughly th...

10 answers  ·  posted 9y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science Creating a realistic world(s) map - Stars

This question is a sort of follow-up to Samuel's previous world map question, Creating a realistic world(s) map - planetary systems. Lots of science fiction stories involve journeying to nearby st...

5 answers  ·  posted 9y ago by HDE 226868‭  ·  last activity 6y ago by HDE 226868‭

Question space astronomy stars
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Rigorous Science What is the best planetary orbit around a black hole in order to support life?

1.Could any planetary orbit sustain life long-term without an imported energy source? I believe that black holes emit Hawking energy. Could that be of use to living creatures? The power emitte...

posted 9y ago by HDE 226868‭  ·  last activity 9y ago by HDE 226868‭

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Rigorous Science Can stars that are not powered by nuclear fusion exist?

Stars generate their energy by fusing lighter elements into heavier elements. The most common reaction in Sun-like stars is the conversion of hydrogen to helium via the proton-proton chain, but hea...

16 answers  ·  posted 9y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Rigorous Science Hot rods into space!

As a first approximation, we treat the rod as a one-dimensional rod of length $L$. On each end is a heat source (the mantles of each of the two "Earths". We can begin to model the system as followi...

posted 9y ago by HDE 226868‭  ·  last activity 6y ago by HDE 226868‭

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Rigorous Science Creating a realistic world(s) map - planetary systems

Ordering of planets (mass and type) Can I start out by jokingly complaining that you picked a rather complex system? We've found a lot of exoplanets, but there are not many that reside in complex ...

posted 9y ago by HDE 226868‭  ·  last activity 8y ago by HDE 226868‭

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Rigorous Science Can people upload their consciousnesses to computers?

The idea of uploading one's personality and consciousness to a computer is a semi-common science fiction trope. It has been suggested as a way to essential immortality. In a story I'm working on, ...

9 answers  ·  posted 9y ago by HDE 226868‭  ·  last activity 9y ago by HDE 226868‭

Question computers
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Rigorous Science Can a planet survive a supernova?

The Sun has nowhere near enough mass to enter the branch of stellar evolution that would lead to a supernova, fortunately for us. However, there are planets that orbit stars that are destined to go...

5 answers  ·  posted 9y ago by HDE 226868‭  ·  last activity 5y ago by HDE 226868‭

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Rigorous Science A planet ringed by stars

Jim2B beat me to the best answer, but there are more solutions. Analyzing a system like this is called the three-body problem, a case of the n-body problem. There are not many stable solutions to ...

posted 9y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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