Mark Olson
  • Member for 3 years, 9 months
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My time machine needs to know when it is
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105 votes

If you can deploy a good quality, wide-angle telescope and take photos of the night sky over a period of more than a few days, you can determine the time down to seconds over a wide range of history. ...

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What are the effects of slicing the Earth in half with a particle beam?
81 votes

All the people who said "We all die!" are correct with good answers, but for most people it won't be the earthquakes that kill them -- they'll already be dead. The leakage from the radiation beam ...

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Superheated bullets and the damage they would deal
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69 votes

The name of the game for weapons is the amount of energy they transfer to the target and how fast and how concentrated it is when it gets there. The kinetic energy of a fast-moving projectile ...

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Why is Cryo-sleep considered harder sci-fi than FTL?
64 votes

The main reason is that space-time is very simple compared to biology, so we understand it much better. We have excellent reasons to think that we have a very good understanding of space-time, and ...

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Could an astronaut in a near-future space ship survive transit through our asteroid belt?
61 votes

Yes they could. Very Easily. Contrary to myth, the asteroid belt is very nearly empty. (See https://physics.stackexchange.com/questions/26712/what-is-the-average-distance-between-objects-in-our-...

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Why would a fighter have a weaker shield than a capital ship?
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59 votes

The key thing about a fighter is speed and agility, and fighters consequently need to be small and as light as possible. While you could build a small ship with large power generation capabilities, ...

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What are the safety margins for destroying a planet from space?
58 votes

Well, at best you're depositing in the planet (or the powdered remnants thereof) energy equal to its gravitational binding energy. According to Wikipedia, the one true source of truth, the ...

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If prey and predator switched places how would this shape the ecosystem?
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46 votes

In a normal ecosystem, the number of prey animals is normally much greater than the number of predators. (Basically, predators like lions need to make kills one a week or so. If lions live an ...

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Tree Shape on a Tidally Locked World
39 votes

This is an interesting observation which I don't recall anyone making before! A world where the sun appears to stand still in the sky (the planet is tide-locked and its orbit is circular) will indeed ...

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Could a cave-in or avalanche in low gravity be dangerous?
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39 votes

Yes, though Enceladus is probably much safer than Earth for these sorts of things. It all depends on how high the avalanche starts from and how much material is involved. A ton of rock or ice hitting ...

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What atmospheric density would be required to allow a human being to fly without wings?
36 votes

We call this "swimming" and you'd need an atmospheric density roughly that of water. The pressure needed to get a gas at that density has serious physiological effects, so just compressing the right ...

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What could cause a baby boom across the western world?
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27 votes

Research suggests that the number of children people have is strongly affected by the economics of children. When having many children is economically advantageous, birthrates go up, and when it's not,...

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Will people suffer from the same diseases on other planets?
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27 votes

Human diseases come from many causes. Intrinsic: Some diseases are due to failures of the human body: mutations (probably most cancers), many auto-immune diseases (including diabetes, alas!), and ...

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Ice Caps around the equator of a planet?
27 votes

Remember that altitude is much more efficient than latitude in cooling the local climate. If you had a generally coolish world and highlands around the equator, you could have everything higher than, ...

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Can a kingdom be destabilised by an influx of enemy gold?
26 votes

Yes, definitely, but it takes a lot of gold and a lot of time. Basically, when a country has a large, long-term influx of wealth, the wealth-generating part of the economy will tend to drive out ...

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Could this bubble float with a person inside?
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26 votes

A cubic meter of air weighs about 1.2kg. A cubic meter of 15% O2 and 85% He would weigh about 20% of that or about .25 kg. so a cubic meter of the O2/He mixture would lift about 1kg. Ignoring the ...

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How likely is the flotsam of a space battle to be captured by our sun's gravity well?
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23 votes

Virtually none of them would be captured and it's unlikely we'd notice anything whizzing past. Basically, an object that falls into a gravity well from infinity (and a light year off is pretty close ...

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In a post-fossil fuel economy, what could natural gas pipelines be used for?
22 votes

It's unlikely that they would be repurposed. Since natural gas is the least carbon-emitting of the fossil fuels, it's likely to continue to be used for longer than coal, and its use is likely to tail ...

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Would a high gravity rocky planet be guaranteed to have an atmosphere?
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20 votes

You ask a tricky question because the case you describe -- a rocky planet with 12G surface gravity -- is extremely unlikely. If the planet is defined as being rocky, then it's made of normal matter (...

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If a patch of desert were magically displaced to the middle of a forest, what would happen to the whole forest after certain periods of time?
20 votes

I'm assuming this is an island in an ocean and not in an inland lake. Given that, there will probably be a fairly consistent wind pattern and it will have plenty of water in it. (Otherwise there ...

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How could a triumvirate remain stable as a political entity over the long term?
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19 votes

The way to start is to ask why people back stab. The answer is, mostly, to gain power and status. The problem with any kind of monarchical government (regardless whether it's an old-fashioned ...

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How close could another solar system be without adversely affecting our own?
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18 votes

The other sun should not be brighter in our sky than Venus at its brightest. This is your tightest constraint. Astronomers are even now doing searches for Planet X and even for brown dwarfs out in ...

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Can fields be destroyed by water so that new ones need to be dug up?
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16 votes

Sure. Assuming the water was fresh, clean water (if it's salt or contaminated with poisons or pathogens, there are other issues) there are two ways a field can be spoiled by a single flood. First, ...

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What is the effect of being sliced by an ultra-thin object?
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16 votes

It would probably kill pretty much any way you used it. To see why, you need to get down to the molecular level. A human cell is made up of a dense dispersion of proteins in water. Human bone is a ...

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Teleportation - the collision of matter problem
15 votes

I think we have enough information to make a pretty good scientific estimate of what happens, given the unscientific premise. The first key point to remember is that matter is almost entirely empty ...

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Is the Concept of Multiple Fantasy Races Scientifically Flawed?
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12 votes

Well, first, magic is scientifically flawed! So if there is magic involved, then the scenario is scientifically flawed. But if there's no magic involved, then there's nothing intrinsically ...

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How can I make a black dwarf star?
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12 votes

Basically, you're asking how to suck the heat out of a while dwarf without sucking all the mass out. That's really hard. The classic three methods of heat transport are radiation, convection, and ...

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How to name a post apocalyptic town?
12 votes

It's hard to imagine a post-apocalyptic town that's not on the site of a pre-apocalyptic town -- good town sites tend to be good town sites, after all. Let the post- names be cut down versions of the ...

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How large is this city and its army?
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11 votes

Maybe the easiest way to answer this question is to look at our own past. Are there any cities in Europe or perhaps China in a similar situation? Perhaps in the Harz Mountains in Germany? If you ...

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Warp drives without exotic matter?
11 votes

With current theory: no. (There isn't even a way to make "ordinary" exotic matter in current theory!) Current theory makes it look very likely that all exotic space-time configurations decay very ...

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