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Earth-like planet spotted orbiting Sun’s closest star

nature.com

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Re: Earth-like planet spotted orbiting Sun’s closest star

#91

Post by cletus »

Loughla wrote: post #74
adflux wrote: post #71

Earlier quoted context omitted.

I will start off by saying I have very little knowledge of physics or astronomy, but reading comments like these feels like I'm watching a 13th century British sailor confidently state what's on the other side of the Atlantic ocean... Do we really know enough to be able to say if a planet is habitable? Or could there be other forms of life that we don't know of yet... We have only recently put a man on the moon, and…

And it's also assuming that any life is like us, with no other technology or way to cycle/recycle heat other than to radiate it into space. I mean, I know the proof of life is us, but the human-centered view of the universe does reek of prior historical "knowledge" that the earth was the center of the universe. I understand searching for life like us, as that is what we can extrapolate from current data. But to use t…

This is the realm of the Fermi Paradox (which is a misnomer because it's not really a paradox at all).

The key question is that if planets are so common and space is so big, why does it seem to be so empty of life? You bring up an argument that maybe life is so different as to be undetectable. It's a fair question to ask but the beauty of the Fermi Paradox is that you don't need to argue about what's most likely. You simply have to be concerned with what's possible.

Let me put it this way. let's say that there is 1 other spacefaring civilization in the Milky Way and they've evolved like you said in a way completely alien to us and as such don't follow a path we can easily detect or at least we don't think to look for it. I can buy that as entirely possible.

But now let's assume there are 1,000 spacefaring civilizations in the Milky Way. What are the odds that every one them falls in this category? What are the odds that none of them follow a similar evolutionary path to us and what we consider highly likely? It becomes increasingly incredulous as you scale up the number of civilizations.

So what's more likely? 1,000 civilizations followed a path alien to us independently? Or that there are few to no other civilizations out there to detect?

To say we're the only 1 of 1,000 to follow this path is really a different kind of human-centric hubris.

Extracting energy from a star is so low-tech it defies logic to think we're the only ones who will (likely) do it.

Re: Earth-like planet spotted orbiting Sun’s closest star

#92

Post by [deleted] »

anders_p wrote: post #87
Udo wrote: post #37

Earlier quoted context omitted.

That's a good point. I have no idea actually where the practical limits would be, especially considering options that arise if the ship has access to a lot of electrical power to generate a protective magnetic field. But even at 0.3c, the trip to Proxima could still be worthwhile for an unmodified human.

You still have the deceleration issue. You need to use the same amount of energy and time to decelerate, as you did to accelerate. So you'd only be able to sustain constant acceleration for half the distance. Then deceleration for the second half of the journey. That would make the travel time much, much longer than your calculations, since you'd be traveling at relatively slow speed for both the first & last 20-25%…

[deleted]

Re: Earth-like planet spotted orbiting Sun’s closest star

#93

Post by aerique »

rbanffy wrote: post #53
grishka wrote: post #50

Earlier quoted context omitted.

I'm not losing hope that there are ways to travel faster than the speed of light that we haven't yet discovered, like bending the spacetime around the spacecraft, or wormholes, or something else of that kind. If various forms of rapidly ejecting matter out of a nozzle really are the only physically viable option for spaceflight, it would be an extremely disappointing universe.

> If various forms of rapidly ejecting matter out of a nozzle really are the only physically viable option for spaceflight, it would be an extremely disappointing universe. Indeed. If that's the case, the universe is an infinitely big and infinitely boring place. OTOH, our future uploaded selves may be able to slow down their clock rates and make the trip so much shorter. And you don't need to leave your dear ones on…

What would that fork think of it?

Re: Earth-like planet spotted orbiting Sun’s closest star

#94

Post by samatman »

BeefWellington wrote: post #89
T-A wrote: post #56

There seems to be some confusion about the meaning of "within the habitable zone". From the paper (Introduction and Conclusions, respectively) [1]: The habitability conditions of Proxima b, which orbits within the HZ of the star, have been extensively studied (e.g. Barnes et al. 2017; Ribas et al. 2016; Turbet et al. 2016; Meadows & Barnes 2018). On the other hand, the candidate Proxima d orbits much closer to the st…

There's also the consideration of the host star to take into account. I dislike the term "Earth-like" in these publications because it conjures images of a strange alien world able to support (human) life. Even assuming there were life capable of withstanding the constant flares from the host star, I suspect it would have to look very different in color and likely composition to the plant life here due to needing to…

My education was in chemistry, I've wondered about this topic before. Visible light is actually special after removing the happenstance of DNA-based visual systems from the picture: IR tends to twist or translate bonds (warming) and UV tends to ionize.

Visible light being right in the middle is the trick which gives us photosynthesis, and sight, because in both cases a photon can be captured by a photosensitive bond. It's harder to come up with plausible photosensitive bonds for IR light, and most anything is photosensitive once you get far enough into UV.

Re: Earth-like planet spotted orbiting Sun’s closest star

#95

Post by jsjohnst »

rbanffy wrote: post #47
5350-uiop-1130 wrote: post #35

Earlier quoted context omitted.

>something like 18 000 years this is why we don't see any signs of life out there. there really isn't any point in trying to venture beyond your home. universe is just too big even at the speed of light when you start venturing beyond your local group.

> even at the speed of light If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter. Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.

> a trip to the next star can be a week-long affair from your point of view

You’d need to travel at around 233x the speed of light to make getting to the nearest star be a week trip, no?

Re: Earth-like planet spotted orbiting Sun’s closest star

#97

Post by samatman »

politician wrote: post #67
semi-extrinsic wrote: post #60

Earlier quoted context omitted.

Maybe an unpopular opinion, but Musk is just plain wrong when he thinks there is any urgency to Mars exploration (or it's just vicarious arguments because rockets are cool). Basically, the tech you need to make a Mars colony truly self sufficient is something like a compact fusion powerplant. Before we have that, no point in worrying about using Mars as a "backup plan", because if Earth was screwed, Mars would have a…

This is hopeful negativism. - They don't need fusion. A StarShip can deposit hundreds of solar panels and put them on the ground. No, dust isn't an issue because they'll bring a roomba. No, this isn't a joke, NASA martian probes' solar panels were cleaned by a light Martian breeze. - They will be able to become self-sufficient rapidly. They're not going to send 1M tons of cargo to Mars without a deployment plan. Spac…

Mars has dust storms which last months or years, it has no ionosphere, and that dust contains enough perchlorates to poison anything we could eat, including us. Ok, that sentence went somewhere odd at the end but, it's true.

A large asteroid has only one of these problems, by virtue of not coming with any atmosphere, ionic or otherwise.

I kinda hope Elon is bluffing and actually plans to head to the Belt. I've penciled it out and and he'd have to be insane not to. Surely he has pencils as well.

Re: Earth-like planet spotted orbiting Sun’s closest star

#98

Post by rbanffy »

anders_p wrote: post #78
rbanffy wrote: post #47

Earlier quoted context omitted.

> even at the speed of light If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter. Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.

You'd have to get very close to the speed of light, before you'd see any really significant relativistic effects. That just isn't practically doable with any technology within humanity's reach, probably for centuries. If it ever will be at all. The amount of energy needed to propel anything at that speed is enormous.

Unless my math is very wrong, at 0.9c the passenger perceived time is more or less half the perceived time from the departure point. That's already quite significant, although not something I could do over a vacation ;-)

In order to spend a leisurely "cruise-ship" week to Proxima you'd need to go very close to c. At that speed, even friction with a non-ideal vacuum is a problem :-D.

Re: Earth-like planet spotted orbiting Sun’s closest star

#99

Post by rbanffy »

jsjohnst wrote: post #95
rbanffy wrote: post #47

Earlier quoted context omitted.

> even at the speed of light If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter. Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.

> a trip to the next star can be a week-long affair from your point of view You’d need to travel at around 233x the speed of light to make getting to the nearest star be a week trip, no?

From the passenger's point of view, yes. For everyone else you'd be veeeery close to c, but not quite there.

Re: Earth-like planet spotted orbiting Sun’s closest star

#100

Post by samatman »

jsjohnst wrote: post #95
rbanffy wrote: post #47

Earlier quoted context omitted.

> even at the speed of light If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter. Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.

> a trip to the next star can be a week-long affair from your point of view You’d need to travel at around 233x the speed of light to make getting to the nearest star be a week trip, no?

Nope! If you obtain the full speed of light then a) you're not made of baryons anymore so congratulations on that and b) no time passes whatsoever between your being emitted in some tight laser beam on planet A, and being transcribed on planet B, from your perspective.

None. Photons don't experience time, they are time.

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