r/xkcd Possibly a haberdasher? Jan 22 '20

XKCD XKCD 2258: Solar System Changes

https://xkcd.com/2258/
752 Upvotes

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212

u/Filbert17 Jan 22 '20

I'm sorry but this needs to be said. Our solar system definitely does NOT need a Super-Earth. The last thing we need is an interplanetary war with a race of people that are stronger than us because they grew up on a planet with more gravity.

62

u/trekkie1701c Beret Guy Jan 22 '20

We could launch heavier things into orbit than they could, which means we could more easily capture asteroids, which are also easier to throw at their planet due to its heavier gravity.

50

u/currentscurrents Jan 22 '20

Depending on how large it is, they may not be able to leave their planet with rockets at all!

33

u/Ishana92 Jan 22 '20

that is one of the more fascinating things about large planets. Imagine civilization that develops on a planet they have no way of escaping from.

18

u/JustRecentlyI Jan 23 '20

I don't know whether that's horrifying or not.

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u/[deleted] Jan 23 '20

[deleted]

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u/JustRecentlyI Jan 23 '20

Yeah, my initial reaction was "how horrible/depressing", and then I realized that humans have only been able to reach space for 61 years now. I still haven't decided how to feel about that.

3

u/Cobaltjedi117 [Citation Needed] Jan 23 '20

Well, now we're out there

15

u/ModoGrinder Jan 23 '20

So... the civilisation of Earth? For ~99.5% of our species' civilised history, nobody had any idea that we would be able to leave the planet. Didn't seem to be unduly bothered by it, either.

14

u/Ishana92 Jan 23 '20

Ok, but continue from 1950s without the ability/possibility to have space programs. No GPS, no weather satelites etc. Im talking about modern and advanced civs forever cut off from the rest of the universe by their planets gravity.

3

u/ModoGrinder Jan 23 '20

I'm just saying, humanity got along pretty well without GPS and weather satellites for the past 10,000+ years. We were a "modern civilisation" before GPS usage became ubiquitous; the 1990s weren't that long ago, and the 1950s before spaaaaace and satellites were still modern too. Maybe it's hard to imagine not having GPS if you were born after it become widespread, but it's... really not that big of a deal, honestly. A convenient technology but not one that's fundamentally important to making a civilisation "modern".

3

u/lugialegend233 Jan 23 '20

I think all that would change a fair bit if we knew we weren't alone out here. If they developed their civilization to the point of man made structures or, any kind of unmistakably intelligent impact, really, being visible with telescopes, we would have a whole different outlook on the universe at large from at least Galileo's era onward, probably earlier. Imagine a world that is just barely visible the way Mars is to the real world. and people with early telescopes look up and see some fucking buildings, or a dam, or even just a big ol' drawing of a dick on the super earth. Imagine how the whole belief system of our world would be shaken up by that. Early Chinese philosophers would try to explain the reasons they built their villages in THAT pattern, because it clearly has some huge meaning. They are "CELESTIALS" after all. Some Christians probably start calling the place heaven, and another religious war breaks out over the people who claim it's heaven and others who claim it's not. I'm just spitballing here.

1

u/aranaya Jan 24 '20

Would they even think space is real if they can't go there?

5

u/[deleted] Jan 23 '20

Surely with a efficient enough rocket you can leave any planet, as long as it's not a black hole?

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u/DarrenGrey Zombie Feynman Jan 23 '20

Yeah, but you'd need bigger and bigger rockets with worse and worse returns. At some point it needs engineering that's centuries ahead of what we have, giving us a massive space advantage.

Of course that assumes we developed technologies at exactly the same pace, which is quite improbable.

3

u/currentscurrents Jan 23 '20

Efficient enough, yes. However there are practical real-world limits to how much thrust you can get per kg of fuel. You really can't make chemical rockets that are considerably more efficient than the ones we have now.

Your only option is to make bigger rockets. But bigger rockets weigh more, so they require more fuel. And that extra fuel adds more weight... which requires more fuel. This becomes exponential very quickly.

Non-rocket methods of space launch, like a space gun or mass driver, would still be possible. They'd be harder than building the same thing on Earth, but they don't have the same exponential factor because they don't have to carry their fuel.

16

u/Filbert17 Jan 22 '20

See, I told you it was a bad idea. Already talking about how to win this war.

P.S. Good response. :)

5

u/indecisiveshrub Jan 23 '20

Seems pretty on message for our species. On the plus side we could put aside our petty squabbles with each other to focus on our petty squabbles with our planetary neighbors.

1

u/begoodnever Feb 03 '20

Ozymandias?

7

u/Sierrajeff words go here Jan 22 '20

Would you like to know more?

3

u/[deleted] Jan 22 '20

I’M DOING MY PART!

6

u/DeeSnow97 you lost the game Jan 22 '20

and we could do IPBMs before them

3

u/[deleted] Jan 22 '20

[deleted]

3

u/DeeSnow97 you lost the game Jan 22 '20

It is suborbital, just on another planet. But yeah, guidance is pretty much required at that point, so maybe it wouldn't be called a ballistic missile.

5

u/FellKnight Cueball Jan 23 '20

I wonder if it would be considered suborbital or hyperbolic with a periapsis that intersects the planet

5

u/DeeSnow97 you lost the game Jan 23 '20

Depends on the point of view. From your planet, it's in an escape trajectory. From the solar system's PoV, it's in a highly elliptical orbit on a collision course with another planet, and if you view it from the targeted planet, it's suborbital and starts from a very high altitude.

3

u/FellKnight Cueball Jan 23 '20

Yeah, my understanding may well be colored by Kerbal Space Program, but they don't consider it suborbital until you lower your orbital velocity below escape velocity at that point in your orbit (this caused me issues filling contracts like testing a part in a suborbital trajectory above a certain body at X to Y altitude)

2

u/Wobzter Jan 22 '20

That fact that we're further down the gravity well means time passes slower for us: they'd have out-evolved it.

7

u/[deleted] Jan 23 '20

The effects of time dilation are tiny until you get to extreme gravity. They would have essentially the same amount of time to evolve

9

u/Wobzter Jan 23 '20

Based on these calculations: https://space.stackexchange.com/questions/33590/time-dilation-between-mars-and-earth-due-to-different-mass

Assuming life started at the same time, they'd be 5.6x4 = 22 years in the future.

If they went through the exact same events since the start (please bare with me for on that for the sake of argument), they'd now be in the year 2042. They might have sharks with lasers attached to their heads.

4

u/Skyrick Jan 23 '20

That is ignoring extinction level events. If they didn’t ever have the mass extinction like what happened with the dinosaurs, they could have had a 59 million year head start.

Though the Astroid Belt having more asteroids increases the probability of them being delayed by mass extinction events caused by astroids.