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Comment by baron816 | Hacker News Reader

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on.

Anatomically modern humans have lived on Earth for 200,000 years, and the creatures we descended from have lived on Earth for 541 million years. Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?

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We could try with a much more doable planet like Mars. We could find out if long term survival is impossible, very difficult, possible but difficult, or doable with the right technologies. It's shocking how little appetite there is for redirecting 50% of the budget which is currently allocated to the military to space exploration.

I understand that the military is partly a large welfare program which doesn't compete with private enterprise due to different technologies and classified material, but I wish there was a movement to invest more of that time, money, and energy on basic research, climate change, energy technologies and space exploration. It's a hard sell though because I suspect that these technologies would compete heavily with established businesses.

On the other hand, government funded resource for DARPA created the place we're speaking on now. You could say that created and entire multidimensional marketplace for business. I'm not sure it would have existed if it were purely down to commercials (take Gopher as an example)

The military application of rockets is only reason we got the tech to reach space and military application of satellites is why we figured out how to stay there and the militaristic penis measuring between nations is only reason we reached moon.

Also, - large part of budget is salaries and pensions. - looks like %budget for military is lowest it's been in 20 years, (in 2015) 16% https://en.wikipedia.org/wiki/Military_budget_of_the_United_...

> looks like %budget for military is lowest it's been in 20 years

The point is the size of it, not the trendline.

NASA got 2-4% to go to the moon. Right now it's at 0.5%. Imagine how much space they could do with 8%.

>It's shocking how little appetite there is for redirecting 50% of the budget which is currently allocated to the military to space exploration.

50% for the military? All the figures I can find say it's 16% of federal spending.

Edit: As others have pointed out. OP may have been suggesting we redirect 50% of the military budget to space not that the military budget is 50% of the national.

They're saying cut the military's budget in half and put the rest toward space exploration.

I believe he's just saying 50% of what is currently allocated for the military, so by your math, 8% of the federal budget.

And the answer is if you accomplished a miracle and cut military spending in half and freed up 8% of the federal budget, there would be a rioting mob charging towards the money... no... that doesn't really capture how much we're talking here... there would be a rioting mob charging the suddenly-available huge pile of MONEY MONEY MONEY MONEY MONEY and there's very little reason to believe space exploration would be any of the winners.

Having near certain evidence of life existing on another planet, due to seeing oxygen present in the emission spectra of an atmosphere of another planet, would be a true game changer for space probe and exploration funding.

Astronomy funding stagnates when its about rocks and geology. Bring real evidence of aliens into the mix and you've defined humanities focus for the next century.

If we discovered actual humans on a near-exact clone of earth, we'd still be about 50,000 years from something relevant here on Earth. Outer space is staggeringly expansive. Staggeringly. Like "your space probe is sad joke" expansive.

We could develop our own alien life right on Earth within that timeframe.

You're thinking about this wrong. As long as we can send probes and/or communicate within compressed timeframes than physical transportation of humans doesn't matter.

E.g. Breakthrough Starshot can get us to many exoplanets within 20-30 years: https://en.wikipedia.org/wiki/Breakthrough_Starshot

"Many" exoplanets? How many planets does Alpha Centauri have?

It is ~4 ly away. If you're willing to go ~10 ly, you get 6 more stars to look at. And it gets far worse from there.

It's now estimated there are more Earth-sized planets than gas giants on most stars, and that every star has at least 1 planet, likely more.

So that's 7 or more planets. That's many.

I'm not the one who downvoted your message because you can't downvote replies to your own post, but I suspect you got downvoted because you crossed threads. If you follow the "parent" up from my post, you'll see that it didn't involve the discussion about finding oxygen.

I agree with the text of your message; it just isn't an appropriate reply to what I said. In fact if such a thing was discovered I'd say all bets are off in terms of the response.

In addition to the clarification of intentions, military spending is in fact 54% of federal discretionary spending.

Entitlement programs like SS and Medicare/Medicaid are raised on a separate tax (you can see it on your paystub), and have zero discretion in how they're spent. It's determined by statute and is automatic, not part of the budget process, and the money never really mixes with the rest of the federal budget.

If you take those out, and take out interest payments which we also don't have much choice in, military spending is 54% of the money that's actually at issue when Congress makes budget decisions.

https://cdn.shopify.com/s/files/1/0177/6150/t/2/assets/Death...

> Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?

People will get more sick, they will need more attention. But that doesn't mean that it is not possible.

Umeå is a Swedish city with a population of over 120,000. January has 33 hours of sun, while June has 286. That's fairly different from your usual place to live. But the city is a completely normal city. You need to go to more extreme situations to get a city that needs extreme changes.

So yes, there are challenges. People living in zero gravity has a lot of health problems, for example. But the most similar the planet the fewer problems there are. And it is cheaper and easier to move there.

Even at 50% the speed of light, adding in a fudge factor for acceleration/deceleration, you're still talking about a trip time of 50 yrs. Even if you go all Neon Genesis and send 15 year olds on the journey, they'll be at retirement age by the time they arrive.

In other words, you'd almost definitely have to send a generation ship. Which means you'd have to have already figured things like artificial gravity, giving birth and raising children in space, etc. It wouldn't be too hard to imagine taking earth values for day/night and gravity, and then gradually over 50 years adjusting them so that, by the time you arrive, you'd have acclimatized to those values on the new world.

Also, nuclear sub crews live 18 hour days, so it's definitely doable.

Interestingly, while on earth 50 years will have elapsed, because of time dilation on the ship only about 40 years will have elapsed. It will get exponentially closer to 0 elapsed time as the speed approaches c. At 90% c only about 20 years will have elapsed [1]. Equivalently, as the travelers approach c, the distance to the destination will appear shorter.

[1] disclaimer: I didn't do the math, i just googled the tables.

The math is actually quite simple to do yourself, your dilation factor is just 1 / sqrt(1-x^2), where x is a percentage of c from 0 to 1. So at 0c, your factor is 1 (obviously), at .5c it's 1.15, and at .9c it's 2.294.

Divide the elapsed time in the stationary reference frame by the dilation factor and you get values that roughly agree with yours.

Of course at 0.9c, the non dilated travel time is 22 years, brought down to less than 10 years due to time dilation.

oh, yes of course, going faster you would obviously arrive earlier even in earth frame of reference :)

We can call it "The B Ark".

But I don't want to die from a disease contracted from a dirty telephone!

There's also time dilation but not much at that speed.

Some kind of sleep hibernation tech, might make it possible to kind of stop or dramatically slow down aging.

Send robots with a genome database so that they can regenerate and raise humans at the end phase of the trip. Or just cut out the humans altogether and let the machines be our legacy.

I'm going to show my nerd colors here but having a thought like this has almost ruined Star Trek for me. For me I often think about atmospheric pressure. There's no way that beings from so many different planets could exist on a single star ship set at 1 Earth atmosphere.

Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?

Venus is 90 bar, Mars is 6 mbar. Maybe not from N=3 in our solar system.

I feel you on Star Trek. It always kills me that 90% of species in the quadrant is a bipedal humanoid, although they did address this in "The Chase" (TNG:S6E20). But I digress.

Non bi-symmetric&quadrupedal animals usually make b-movies or enemies in horror genre. I am also interested in life forms in other quark/lepton/ muon sorts in the current universe if possible.

I m a firm believer that non-natural, non-random life forms will dominate the space exploration including robots, augmented humans, bio-robo hybrids and Supra and sub swarms of those.

> Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?

No. Proof: Venus/Earth.

I see. Thanks

You must have missed this: https://en.wikipedia.org/wiki/The_Chase_(Star_Trek:_The_Next...

Yeah this is a lot of suspension of disbelief, but Star Trek has a bunch of those, so it's not so out of left field.

One common solution in SF novels is for aliens to be in an atmosphere suit, typically very high tech (thin and floating). In extreme cases, the suit would encase the whole body in gel fluid and also inject it into lungs and other orifices to withstand pressures from different gravities or ship acceleration.

In essence, you need a lot of tech to allow diverse aliens to spatially co-exist.

Edit: All of this ignores food. Typically, stories solve that with some kind of nano-replicator that can make any combination of chemicals safe for aliens to eat.

You put on your nerd goggles and that's what ruins Star Trek for you?

Humans have a range of about .25 to 50 atmospheres of pressure, as long as you have the right amount of oxygen and not too much nitrogen.

So that particular aspect is not something to worry about.

Thats why I enjoy the Culture series so much - why search endlessly for a habitable planet when you can just build yourself a nice, perfectly tailored orbital?

And in doing so tidy up the system of wandering debris (a trade-off whose conservatory elegance is almost blissfully appealing to the average Mind).

Humans manage to live in the Sahara, the Himalayas, tolerate being a hundred pounds overweight fairly well, Alaskans deal with weird day/night cycles, etc. I don't think we're quite as sensitive as you make us out to be.

Also, consider the context within which we are considering such a trip: survival of the species long term. Maybe adjusting to the gravitation and day/night cycle of a new planet is absolutely terrible. Choosing that over extinction is still the easiest choice in the universe.

I don't know about the day/night thing, but we could definitely get used to more gravity. When coming in for landing you could decelerate over the course of the last year or so at a slowly increasing rate to an effect of slightly more gravity than the planet you're landing on. You slowly grow accustomed to that and then when you land, you actually feel lighter on the surface of the planet.

"Anatomically modern humans have lived on Earth for 200,000 years, and the creatures we descended from have lived on Earth for 541 million years. Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?"

To further your (good) point about gravitational and diurnal differences, it is worth also considering the experience of native americans in the face of novel (to them) micro-organisms brought in by europeans.

These diseases were not from another solar system and they were related to animals that had local analogs ... and yet they were devastating (up to 90% mortality in some places) to the native population.

On another planet the bacteria, viruses and fungi (not to mention the potential discovery of previously unknown biological primitives) would be completely novel to us.

I wouldn't be shocked if there was 100% mortality outside of containment/quarantine after a week or two.

EDIT: On the other hand, imagine if we found that our genetic code did contain information related to what we found offworld ... wouldn't that be fascinating ...

It depends wouldn't it? If the biology and chemistry of those organisms prove to be completely different (e.g, by not being carbon based), then couldn't their bacteria prove to be utterly inert in relation to our bodies?

yeah, if diseases have trouble transferring to us from animals, I find it doubtful they will spread to us from aliens

Earth parasites attack us because they have evolved to do so. If alien analogues of parasites did so, it would just be a completely random thing.

I'm left wondering these same kind of issues every time there's a Mars habitation post. Having a third the gravity, microscopic dust, and a complete lack of nature (or Internet) seems to be trivial to some people.

Also: no magnetosphere, so none of the same barrier to most cosmic radiation behind which we've evolved.

> Having a third the gravity

Sounds fun!

> microscopic dust

Found on earth! I change my HVAC filters regularly.

> and a complete lack of nature

There's plenty of nature on Mars. Not much life, but we'll bring that with us. I'd suspect early colonists will have more plant life in their quarters and living areas than your average NYC resident.

> or Internet

I'd fully expect a solution along the lines of Netflix's edge caches for this by the time we're seriously considering building a base. Daily snapshots of Reddit, StackOverflow, major news sites, etc.

You think existing in a third the gravity, most likely for the rest of your life, wouldn't effect your body in untold ways?

As they say of NYC, "if you can make it here, you can make it anywhere".

People living in large urban centers are essentially 100% disconnected from any sort of natural day/night light cycles, but they still manage (with, admittedly, some negative health effects). Same deal with gravity; the human body can support people who way 2x the average for their demographic, so I don't think 10% different gravity will matter much.

In the worst case, we could probably do genetic modification or just use exogenous hormones to help adapt to weird sleep cycles.

Why would gravity be the problem? There are people that weigh twice the weight of other people same height. I guess very low gravity could affect calcium in the bones and there could be other various effects. But people are life and life is adaptable. Day/night cycle? It varies greatly on earth too. Also one person's nightmare is just life for some other.

> There are people that weigh twice the weight of other people

This isn't the same thing at all.

Growing up in a high gravity environment would definitely alter your growth. We've also seen that it leads to fluid imbalance, cardiovascular issues and general fatigue

> cardiovascular issues and general fatigue

Sounds pretty much the same as obesity to me.

Calcium and the weak bones is a problem only if you are planning to return to Earth. The first 20ly journey will probably be a one direction trip.

Adaptation isn't a great issue imho, the main issue is whether the 20th century sci-fi trope of colonizing space is a good idea in the first place and I'm pretty skeptical it is. These threads always strike me as incredibly naive in just assuming we would want to go anywhere/everywhere.

Gene manipulation maybe? Won't work very well I suppose for existing humans, but i imagine we could eventually learn to modify genes in embryos to make them more adaptable to different environments

Weird question. Can we make Earth a spaceship by somehow manipulating the orbit of the moon?

We'd have to figure out how to get the earth spinning beyond the escape velocity of the Sun. So, probably not just by manipulating the orbit of the moon.

Well, we'd need to apply 40 km/s of delta-v. The moon weighs 1/80th as much as the Earth. By the rocket equation, we'd have to throw the material of the Moon away from Earth at 3219 km/s or 1/100 of the speed of light in order to accelerate Earth enough.

I'm sure it wouldn't be easy, but humans have proven to be very adaptable.

>proven to be very adaptable

to conditions on Earth

Sure. And once we adapt to conditions on Planet X, we'll be hardly human.

At this point, we might have to see that it is necessary to genetically modify humans so that they can survive in these alien environments. Maybe we cannot be comfortable with 10% higher gravity, but we can _make_ ourselves be comfortable.

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