341–350 of 410 posts
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Also it just seems to be water, they’re obviously not 100% sure it’s not something else that’s reading as water.
How easy is it to have different mixtures of substances that lead to similar enough absorption apectra that they are indistinguishable with the available resolution and sensitivity?
Some caveats per Marina Koren https://twitter.com/marinakoren/status/1171873631808438273 1. This planet probably doesn’t have a solid surface 2. Being in the “habitable zone” doesn’t mean a planet is habitable 3. The detection is of water molecules, chances are the water only exists as vapour in the atmosphere of this small gas giant. 4. If you ask 10 astronomers about this you will get 11 opinions
> Being in the “habitable zone” doesn’t mean a planet is habitable True. Being a spooky near twin of Earth isn't necessarily enough. The air inside popcorn factories is basically identical to the Earth's atmosphere, but breathing in diacetyl, a butter flavor you'll find in that air, will kill you a few months or years later. Popcorn lung really undermined my naive view that we would one day be able to run a scan or a…
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I mean that sounds pretty awesome if you invested your funds well. I'd definitely be willing to be the first person who did that.
Where can you invest that would still recognize those funds as yours after 222 years?
They were going to the Barnard Star, but it had binary planets where one was all water.
Good book (if I recall)..
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As a startup founder, I learned the hard way to not assume progress will ever be exponential.
Over any timeframe, the rate of progress between the beginning and ending of the timeframe can be phrased as exponential for some exponent. It's just a matter of accurately estimating what that exponent is. I take your point though - hypergrowth cannot be sustained - and estimating that exponent is fairly valueless if volatility is too high. This is all just math fun that won't be valuable if we bump along for hundre…
I got into the Wait Calculation[1] a few weeks back and made a Jupyter notebook out of it. At our current max speed (692,000 km/hr, stated max speed of Parker Space Probe), it would take about 173,000 years to get to that planet. We could instead choose to Wait and grow our tech. By picking a constant annual growth rate and then doing some calculus to find the minimum, we can calculate the shortest possible time it w…
Does that include slowing down and stopping, or would you be at max speed by the time you got there? I always thought that was a very well thought out aspect of The Expanse: spend half the trip accelerating, then flip the ship around and spend the other half slowing down (aka accelerating in the opposite direction).
> I always thought that was a very well thought out aspect of The Expanse: spend half the trip accelerating, then flip the ship around and spend the other half slowing down (aka accelerating in the opposite direction).
With current technology you would not do this, since that means using extra fuel that weighs a lot and thus increases the force required for the same amount of acceleration as you'd get with less fuel and less burn.
Of course that changes drastically if the fuel required for more acceleration (and its container) is very light-weight. I would assume fusion or fission based thrusters would be better in this regard, however I think currently those produce very little acceleration in a vacuum compared to combustion thrusters.
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It isn't habitable even if it's a super Earth because the gravity would be 8g if it's 8x the mass of Earth.
That's not how it works. The moon is 1% of Earth's mass, but has 16% of our gravity. I'm not entirely clear on the deciding factors, but it's probably mostly density.
Rough napkin formulas below. Apologies for formatting)
F=ma F(g) = GMm/(r^2) ma=GMm/(r^2) a=GM/r^2
Volume of a sphere = (4/3)pir^3 mass of a planet = density volume M=ro(4/3)pir^3
a=(Gro(4/3)pir^3)/r^2 a=Gro(4/3)pi*r
given that G, 4/3 and pi are constants, it comes just to density multiplied with diameter.
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It isn't habitable even if it's a super Earth because the gravity would be 8g if it's 8x the mass of Earth.
That's not how it works. The moon is 1% of Earth's mass, but has 16% of our gravity. I'm not entirely clear on the deciding factors, but it's probably mostly density.
That's why the gravity on the surface of neutron stars is so high, even when the mass is the same as our Sun.
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Every time I think I’m closer to understanding matters of time and space...
Here's a quick analogy to help (loosely adapted from Brian Greene): You're on a grass field, sitting on one of those riding lawnmower thingies, with a broken throttle. It's moving at a fixed speed of 1mph. You can't ever change its velocity. But you can steer it. If you are going precisely east-west, then it means you're not going north-south. The more you go north-south, the less you'll be going east-west. If you're…
This may not be a problem for some definitions of time, but for the notion of time which goes from past to future, I don't think the analogy holds very well.
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As a guy who lives in a finite world where energy comes mainly from fossil fue in a way or another, I do not assume that any constant progress in energy supply is something achievable.
No, and traveling near lightspeed is likely hardly possible. However, fusion will likely become a reality within our lifetimes, and if we can build fusion powered spaceships, we could likely reach a fraction of the speed of light, say, 0.2c. I don't think it's that crazy to think we could do that a few centuries from now. That still means it would take over 1000 years to reach that planet. Personally, I think that if…
This will make the 22 year trip to Alpha Centauri more palatable.
1000 year trip in a single lifetime will require some life extension as well