# Tag Info

12

As promised, here's my answer, covering the grids I sometimes use. The Geneva Grids These are extraordinarily comprehensive - they actually meet all of my requirements and then many more. Lejeune & Schaerer 2001 go into some of the nitty-gritty details, but the models have been updated even more in the last two decades. Here are some of the features: ...

10

I don't think it is possible. Newton calculated that the impact depth of a projectile is roughly equal to its length. The impactor carries a given momentum. To stop the impactor, this momentum must be transferred onto another mass. Since the impactor's velocity is so high that cohesion within the target material can be neglected, the momentum can only be ...

9

Saturn Cloud Deck Topography Where is worth living in this vertical real-estate column? Here is some data on how temperature and pressure vary with altitude, and some interesting landmarks along the way. Interesting Places : 5 atmospheres (5 bar) : inside the ammonia and hydrogen sulfide cloud decks, so that something useful might be harvested. 5 ...

6

Ammonia is a greenhouse gas. Not the easiest question because although you can find data that absorbs energy in the infrared spectrum (one of the qualifies for a greenhouse gas), it is not considered in publications dealing with the greenhouse effect because ammonia has such a short residence time in our atmosphere. Our current atmosphere, that is. I ...

5

It is well beyond impossible, if you assume the alien god has mass. If you do something clever like positing the alien god is made up neutrinos, as one comment pointed out (mass not the issue with them), then it's pretty easy to get 99.99999999% of it sent thru the Earth. However, your desire for "hard science" in the face of a supernatural alien is ...

4

Nothing good Let's have a look at a few data points along the way to the impossible humanoid: 343 m/s (approx.) supersonic flyby of F/A-18 Hornet in Mythbusters episode to test if sonic boom will break glass. Glass was broken in a pass at 200 feet (60 m) above a test shed. 1200 m/s was the muzzle velocity of the British Ordnance QF 17-pounder, which fired ...

3

If other non-human mammals survived, one can see what they are able to eat without having any health problems. For example, pigs and monkeys would probably get poisoned from similar food as humans would, but even something like rats might be close enough. If a rat is eating a berry and poops it's seed, then the berry is probably edible and the seed might not ...

3

1 + 1 = 700(ish) Assumptions and approximations: Earth has a mean radius of 6371 km. The Kármán line for the existing, unmodified Earth atmosphere is 100 km up. Even if doubling the mass of the atmosphere doubled this to 200 km (it would not), the effective atmospheric surface area that can radiate energy back into space would change by a trivial ...

3

The pressure would increase by a lot. From the ideal gas equation (nRT=PV) doubling the quantity of gas (n = number of molecules * a constant) would double the pressure assuming a constant volume. It is unlikely that the volume of the atmosphere would remain constant, so I suspect the increase would be much less than double, but the pressure increase would ...

2

Broadly speaking, a hypersonic penetrator, and which is moving faster than the speed of sound in the material it is made of, will penetrate roughly to its own length. So, if you have a penetrator more than 8,000 miles long - which would need to have a reasonable width -- and fire it at a few miles per second, you might get somewhere. Best might be to use a ...

2

Actually, the larger the animals, the easier it is for it to have a brain with human level intelligence. There is a minimum size of brain necessary for human level intelligence. Nobody knows what that minimum size is. There are approximately 6,500 known species of mammals at the present. https://www.sciencedaily.com/releases/2018/02/180206090658.htm1 ...

2

Towards an Answer... The question of gigantic humanoids has come up in Worldbuilding a couple times in the past, and we do have some data on relative maximums in size for Homo sapiens. Historically, the tallest human ever was just under nine feet tall; and the heaviest human ever was 1,400 pounds (100 stone). Both men were at least of average intelligence:...

2

The answer depends on the depth, the distance from the bottom and the distance from the surface. The explosion goes off, the water vaporizes and you have a bubble. The bubble is under pressure from the surrounding water and starts to collapse. The pressure inside the bubble builds up and overshoots the surrounding water pressure, so the bubble starts to ...

1

Yes, it would increase the magnetic field. The strength of Earth's magnetic field in the outer core can be roughly estimated by$^{\dagger}$ $$B_{\text{core}}\sim\sqrt{\frac{\rho\Omega}{\sigma}}$$ where $\rho$ is density, $\Omega$ is rotational velocity and $\sigma$ is electrical conductivity. These are all material properties of the core, which would not ...

1

Like many organs, the vertebrate brain actually evolved because of our large size--the larger you are, the more you need a dedicated system to communicate quickly between cells. I don't see any reason being large would make anyone less intelligent. Elephants and whales are both pretty smart animals! However, because it takes longer for messages to travel ...

1

Maybe by using artificial micro-black hole as a bullet? Benefits as an extreme high energy directed weapon, that avoids problems such as Newtonian momentum transfer relation to width of the low momentum projectile, relating it to superior density and quantum mechanical phenomena instead, both of which were enough on their own to avoid usual Earth-...

1

Given the realities of impact depths, you're going to need something with a LOT more bang than any conventional or unconventional weapon remotely feasible. Andrew Brezca suggested smacking the earth with a moonlet, I think that's not quite enough. You'll definitely destroy everything on the earth's surface, and the earthquakes it'd produce would be ...

1

Maybe, if you hit the Earth with a Mars-sized projectile According to the giant-impact hypothesis, a long long time ago a planet roughly the size of Mars struck the Earth. The resulting debris formed our Moon. It's unclear from your question if you want to have a precise sniper-like shot that penetrates the planet or if you'll accept a... messier... ...

1

You have two questions that really aren't related at all. First, on the question of alien creatures evolving a skeleton based on chitin, it seems plausible, but I don't know enough about the properties of chitin to give a definitive answer. The structural parts of bones are composed of mineral crystals, mainly calcium phosphate (hydroxyapatite), embedded ...

1

Absolutely! I don't know of any mammals that display Iridescence, but I think that you could have evolutionary paths where that could be reasonable. This video shows a variety of animals with iridescent properties. https://www.labroots.com/trending/videos/11889/science-iridescence-animals But basically if you have structures that start to approach the ...

1

The biggest problem is definitely the methane. Methane is only a little lighter than earth's air. This gives you slightly more time to prevent a catastrophic reaction, as it would take a little longer before the methane enters the hole in the dome. That's where the good news stops. Gasses mix very quickly thanks to entropy, and in this wherever the air and ...

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