Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Water found on a potentially life-friendly alien planet

nationalgeographic.com

Post reply on HN
Print view View original

101–110 of 410 posts

Re: Water found on a potentially life-friendly alien planet

#101

Post by 0xffff2 »

soulofmischief wrote: post #36
archgoon wrote: post #4

Earlier quoted context omitted.

It's 111 light years away. For all intents and purposes, that's a one way trip right there; irregardless of the rocket equation. Even at relativistic speeds, you can't come home anymore.

We're talking about just escaping the surface gravity, not returning to Earth.

If you can get there from 111 light-years away, you can probably also solve the higher surface gravity. While the former problem is theoretically solvable in a straightforward way, both are impractical with our current understanding of physics and material science.

Re: Water found on a potentially life-friendly alien planet

#102

Post by dogma1138 »

sandworm101 wrote: post #16
dogma1138 wrote: post #7

Earlier quoted context omitted.

I think what the GP refers to is that there isn’t enough energy in chemical rockets to overcome its gravity, even flight might not be even possible albeit that’s also dependent on the density of the atmosphere to some extent.

Flight would actually be easier on such a planet. The advantage of increased atmospheric density is greater than the downside of the increased gravity.

That is of the atmospheric density is higher, we don’t know the composition and temperature don’t forget that at higher pressures the boiling point of water is higher so it might not actually have water vapor in the atmosphere.

The atmosphere can also be much more shallow than earth.

Also I was more referring to winged flight than balloons balloons might be a problem of their own if the pressure at ground level is too high for them to inflate normally.

Between earth and Venus there are a lot of options so if the atmosphere is similar to earths sans the water vapor I’m not entirely sure flight would be actually easier I can probably do some napkin maths over the weekend for this.

Re: Water found on a potentially life-friendly alien planet

#103

Post by ngold »

dkural wrote: post #52
DidISayTooMuch wrote: post #46

Earlier quoted context omitted.

Wait, is this correct? Doesn't 111 light-years mean even light takes 111 years to travel through? And light travels at 1c.

Light does not experience time at light speed - it is stuck in a static moment. So from our stationary perspective, light takes 111 years to come from a 111 light year distance, but from light's perspective it takes an instant.

Super fun. Great one. Actual replying to save this thread so I can go back and check some of this out. Looks neat.

Re: Water found on a potentially life-friendly alien planet

#104

Post by vecter »

typeformer wrote: post #94
fooker wrote: post #74

Earlier quoted context omitted.

Evidence?

The government has been studying UFO's at the highest levels since at least 1947 and likely prior. You don't study something closely for 7 decades and not learn anything. https://www.cia.gov/library/center-for-the-study-of-intellig...

UFOs are literally just Unidentified Flying Objects. Doesn't mean that they're alien in origin (and in fact, they're almost certainly not).

Re: Water found on a potentially life-friendly alien planet

#105

Post by dogma1138 »

soulofmischief wrote: post #38
sandworm101 wrote: post #16

Earlier quoted context omitted.

Flight would actually be easier on such a planet. The advantage of increased atmospheric density is greater than the downside of the increased gravity.

So... if one made a very aerodynamic craft, and launched at a more extreme lateral angle, do you think it would supplement the chemical rockets enough that escape would be possible?

not really going to orbit is about velocity not altitude the gravity at low earth orbit is pretty much the same as at sea level.

The savings you get when launching from say an aircraft at 40,000 feet mainly come from not having to go through max-q at sea level the relative amount of propellant you’ll need to get to orbit is the same you can just use a smaller rocket but it doesn’t help to overcome the rocket equation trap.

Re: Water found on a potentially life-friendly alien planet

#106

Post by escapecharacter »

calgaryeng wrote: post #91

Isn't it odd to think that one day, there will be a top post on Hacker News: "Alien Life Discovered on Nearby Planet (430 points)".

Right underneath “10 Reasons why Git 3.7 is going in the wrong direction (583 points)”

Re: Water found on a potentially life-friendly alien planet

#107

Post by atonalfreerider »

pierre_d528 wrote: post #93
transreal wrote: post #2

With a planet this large, visiting it would be a one way trip due to the "The Tyranny of the Rocket Equation" [0]. I'm looking forward to the day we start finding exo-planets that are closer to Earth in size and which could potentially have space-faring races (and which we could leave if we were ever to visit them). [0] - https://www.nasa.gov/mission_pages/station/expeditions/exped...

Or we could shift to an other side of the universe by "inverting" the mass of the ship where the speed of light is much higher[1]. Cosmology is so cool... too bad we do not have time for that: we cannot even cure the common cold! [1]: https://januscosmologicalmodel.com/pdf/2014-ModPhysLettA.pdf Cosmological bimetric model with interacting positive andnegative masses and two different speeds of light,in agreement with…

> Special Relativity can be summed up in the sentence: “We live in a spacetime which is an M4 manifold with a hyperbolic Lorentz metric of signature (+−−−)”. General Relativity can be stated accordingly: “The Universe is an M4 manifold with a Riemannian metric of signature (+−−−)” which is a solution of the Einstein equation:Rμν−12Rgμν+Λgμν=χTμν.

It sounds like you get anti-gravity for free along the way to getting superluminal travel.

Re: Water found on a potentially life-friendly alien planet

#109

Post by 0xffff2 »

mrkstu wrote: post #75
scrumbledober wrote: post #39

Earlier quoted context omitted.

most of the energy spent getting to that 400km low earth orbit is spent accelerating to very very fast lateral speeds. If you use a balloon to get your rocket up as high as you can before launching it you limit the weight of the rocket you can lift up there, and most of the weight of rockets is used to gain that lateral speed. The plane + rocket idea has been shelved for now, as reusable rockets have decreased the pr…

Isn’t that orthogonal to interplanetary travel though? If you go straight up far enough you’ll be out of Earth’s gravity well. You’ll still need acceleration to escape the solar gravity well, but you’ll never need horizontal acceleration necessary for Earth orbit.

>If you go straight up far enough you’ll be out of Earth’s gravity well.

While you could theoretically do this by accelerating directly up, You still have to accelerate somehow.

Re: Water found on a potentially life-friendly alien planet

#110

Post by arbuge »

typeformer wrote: post #25

I say let's go. Now, whether you believe it or not, it is a fact that the US government has acquired alien technology and yet continues to keep it hidden by being stuck in a cold war mindset of, "well, we can't let the Chinese or Russians get their hands on this". That is the ultimate expression of narrow thinking, especially when there is a whole universe out there! Bring on the downvotes but history will vindicate…

> whether you believe it or not, it is a fact

Extraordinary claims require extraordinary evidence. Where's yours?

Post reply on HN