Earth-sized planet found in Proxima Centauri's habitable zone

[Simon_Jester]

Fuck.
Right. This means that habitable planets are around 10% of star systems.

Uh... does it? Why?

If that's true, then there should be tens of billions of habitable planets in the galaxy. Since life seems commons, there should be billions of civilizations that have existed, and hundreds of thousands around now. There aren't. Therefore, either we can't find them, life is difficult, or intelligent life exterminates itself easily.

Or:

1) Life is common but 'advanced' life is rare. That is, there are lots of planets out there with nothing more advanced than algae, or jellyfish, or water planets covered in marine life but nothing that can readily adapt for tool use.

2) Advanced life is common but intelligent life is rare. Say, because intelligence is actually NOT that reliably effective an adaptation to one's environment. As illustrated by the fact that so far as we know, complex life on Earth has been around for two hundred million years, and features like fast running and strength and even flight have evolved multiple times in parallel, but intelligence has only emerged once.

3) Intelligent species routinely last millions of years in recognizable form, but do not give off readily visible emanations we can detect during that time.

4) Intelligent species survive rather well, but 'metamorphose' into forms unlikely either to colonize the galaxy or to give off obvious emanations (e.g. developing more and more advanced VR technology until they disappear into their own World of Warcraft servers). They may be all over the galaxy, 'alive' and happy, but not having any conspicuous effect on the interstellar landscape.

5) Some combination of (1), (2), (3), and (4) causes there to be no visible intelligent species within our detection range, combined with other factors that make widespread interstellar colonization rare.

[Rhadamantus]

Fuck.
Right. This means that habitable planets are around 10% of star systems. If that's true, then there should be tens of billions of habitable planets in the galaxy. Since life seems commons, there should be billions of civilizations that have existed, and hundreds of thousands around now. There aren't. Therefore, either we can't find them, life is difficult, or intelligent life exterminates itself easily.

An intelligent species that didn't build anything we could detect with radio telescopes could be sitting around Proxima Centauri and be utterly unknown to us.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

[The Romulan Republic]

Fuck.
Right. This means that habitable planets are around 10% of star systems. If that's true, then there should be tens of billions of habitable planets in the galaxy. Since life seems commons, there should be billions of civilizations that have existed, and hundreds of thousands around now. There aren't. Therefore, either we can't find them, life is difficult, or intelligent life exterminates itself easily.

An intelligent species that didn't build anything we could detect with radio telescopes could be sitting around Proxima Centauri and be utterly unknown to us.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Still doesn't preclude a civilization up to modern/near-modern technological development.

Your argument also seems to presume that their is a set path, set levels of technological development that all civilizations will follow.

[Eternal_Freedom]

Fuck.
Right. This means that habitable planets are around 10% of star systems. If that's true, then there should be tens of billions of habitable planets in the galaxy. Since life seems commons, there should be billions of civilizations that have existed, and hundreds of thousands around now. There aren't. Therefore, either we can't find them, life is difficult, or intelligent life exterminates itself easily.

An intelligent species that didn't build anything we could detect with radio telescopes could be sitting around Proxima Centauri and be utterly unknown to us.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Where does that distance figure come from? I haven't come across anything in the astronomy literature I follow describing how far away we could detect fusion drives (or any type of engine system for that matter).

[Simon_Jester]

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Then perhaps they have not seen fit to build fusion torch drives, if they exist. Or perhaps they are done building and using such drives, and no longer bother with them, and have not bothered to do so during the half-century or so when we would be capable of detecting them.

There's a difference between saying "no one is firing a fusion torch to power an interstellar spacecraft at any point on our light cone within one hundred light years," saying "there are no actively fusion-using civilizations within one hundred light years," and saying "there never were any fusion-capable civilizations within one hundred light years, or if there were they're all dead."

[Rhadamantus]

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Then perhaps they have not seen fit to build fusion torch drives, if they exist. Or perhaps they are done building and using such drives, and no longer bother with them, and have not bothered to do so during the half-century or so when we would be capable of detecting them.

There's a difference between saying "no one is firing a fusion torch to power an interstellar spacecraft at any point on our light cone within one hundred light years," saying "there are no actively fusion-using civilizations within one hundred light years," and saying "there never were any fusion-capable civilizations within one hundred light years, or if there were they're all dead."

If a civilization has moved on from building fusion drives, then they have either fallen back or used something more advanced. More advanced stuff would be more easily detectable. If we use a drake equation, and say that there have been 1000 civilizations in the 300 ly radius sphere around us (10% of stars have a habitable planet, 10% of habitable planets have advanced life, 10% of planets with advanced life have intelligence), then we probably wouldn't expect to see one. We would expect to see their remeants.

[Rhadamantus]

An intelligent species that didn't build anything we could detect with radio telescopes could be sitting around Proxima Centauri and be utterly unknown to us.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Where does that distance figure come from? I haven't come across anything in the astronomy literature I follow describing how far away we could detect fusion drives (or any type of engine system for that matter).

Entering space (Creating a spacefaring civilization) by Robert Zubrin. Somewhere around page 263.

[Rhadamantus]

An intelligent species that didn't build anything we could detect with radio telescopes could be sitting around Proxima Centauri and be utterly unknown to us.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Still doesn't preclude a civilization up to modern/near-modern technological development.

Your argument also seems to presume that their is a set path, set levels of technological development that all civilizations will follow.

It'd be very odd for a civilization to be at exactly our level of development.

[The Romulan Republic]

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Still doesn't preclude a civilization up to modern/near-modern technological development.

Your argument also seems to presume that their is a set path, set levels of technological development that all civilizations will follow.

It'd be very odd for a civilization to be at exactly our level of development.

In case it wasn't clear, it would permit a civilization of any kind pre-radio.

[Simon_Jester]

If a civilization has moved on from building fusion drives, then they have either fallen back or used something more advanced. More advanced stuff would be more easily detectable.

Or so you think.

If we use a drake equation, and say that there have been 1000 civilizations in the 300 ly radius sphere around us (10% of stars have a habitable planet, 10% of habitable planets have advanced life, 10% of planets with advanced life have intelligence), then we probably wouldn't expect to see one. We would expect to see their remeants.

More to the point, you're missing a large number of possibilities and issues here, several of which I have already covered in previous posts, and which you have ignored. I don't want to repeat myself too much, it's too late in the night.

But to cover the most rudimentary, obvious points:

1) The aliens may simply not build massive fusion rockets.

2) To expand on this, the aliens may be satisfied with lifestyles that do not require massive fusion rockets (e.g. infrastructure sustainable on one planet with possible limited space infrastructure, and the population living mostly inside their own VR servers to the point where technological change slows to a crawl).

3) Alternatively, the lifespan of a civilization could be measured in millions of years, or even longer, but with limited interstellar colonization for a variety of plausible reasons. Which loops back to (1), because we'd have to just happen to be looking at a civilization in one of the handful of years where they are firing up a massive fusion rocket. If that is a rare enough occurrence, we can't count on spotting the massive fusion rocket.

4) Massive fusion rockets may not turn out to be a favored form of energetic propulsion system compared to, say, laser-boosted light sails. Which would only be noticeable if the laser was aimed directly at us. Again, this loops back to (1).

Basically, you simply cannot reasonably take "we haven't seen any massive fusion rockets nearby in the last few decades" and use it as evidence to support "therefore, all the aliens that evolved before us are dead and civilizations die out quickly."

[Simon_Jester]

Basically, Rhadamantus, you're using a variation on the "apes or angels" thesis.

What it comes down to is that if we go exploring the galaxy in search of intelligent life, we should expect to find that most intelligent species have existed much longer than us. If they're still around, they'd be far more advanced than we are. Another handful of species would have existed significantly less time than us.

But a species much younger than us would be pre-technological in a state of hunter-gatherer life, or its equivalent adapted to an alien ecosystem. In other words, "apes."

And a species much older than us would presumably have technology that makes ours look like rocks and sticks. In other words, "angels."

And you then go on to ask "where are all the angels? I cannot see them from my front porch as I would expect. They must all be dead."

...

The problem is that this chain of reasoning makes some very shaky assumptions.

One is that the "angels" use technology that looks the way we expect it to look. For instance, thirty or forty years ago we assumed that our radio signals would blanket the night sky and aliens could easily find us that way. That was when we relied on broadcast television. Someone invented cable, and now we transmit a lot less information and energy into the sky. We cannot rule out the possibility that highly advanced aliens simply use different technologies, unknown ones or simply unforeseen ones. Technologies that are harder for us to detect at long range.

Another is that there may be practical limits on the advancement of the "angels" that allow them a happy and stable existence without producing huge technological signature. If the average intelligent species decides to relax on one planet and does not massively colonize its own solar system and isn't loopy enough to start dismantling planets for Dyson spheres... we might have a much harder time noticing them, than if we assume they will do all that heavy construction.

And of course a third is that if we're looking for angels by observing something that has a transient signature by nature (i.e. huge fusion rockets, which are only visible while firing), we may simply be looking in the wrong time, or the wrong place.

[Rhadamantus]

Still doesn't preclude a civilization up to modern/near-modern technological development.

Your argument also seems to presume that their is a set path, set levels of technological development that all civilizations will follow.

It'd be very odd for a civilization to be at exactly our level of development.

In case it wasn't clear, it would permit a civilization of any kind pre-radio.

Yes, but if there are many pre radio civilizations, you'd also expect post-radio civilizations.

[Rhadamantus]

If a civilization has moved on from building fusion drives, then they have either fallen back or used something more advanced. More advanced stuff would be more easily detectable.

Or so you think.

If we use a drake equation, and say that there have been 1000 civilizations in the 300 ly radius sphere around us (10% of stars have a habitable planet, 10% of habitable planets have advanced life, 10% of planets with advanced life have intelligence), then we probably wouldn't expect to see one. We would expect to see their remeants.

More to the point, you're missing a large number of possibilities and issues here, several of which I have already covered in previous posts, and which you have ignored. I don't want to repeat myself too much, it's too late in the night.

But to cover the most rudimentary, obvious points:

1) The aliens may simply not build massive fusion rockets.

2) To expand on this, the aliens may be satisfied with lifestyles that do not require massive fusion rockets (e.g. infrastructure sustainable on one planet with possible limited space infrastructure, and the population living mostly inside their own VR servers to the point where technological change slows to a crawl).

3) Alternatively, the lifespan of a civilization could be measured in millions of years, or even longer, but with limited interstellar colonization for a variety of plausible reasons. Which loops back to (1), because we'd have to just happen to be looking at a civilization in one of the handful of years where they are firing up a massive fusion rocket. If that is a rare enough occurrence, we can't count on spotting the massive fusion rocket.

4) Massive fusion rockets may not turn out to be a favored form of energetic propulsion system compared to, say, laser-boosted light sails. Which would only be noticeable if the laser was aimed directly at us. Again, this loops back to (1).

Basically, you simply cannot reasonably take "we haven't seen any massive fusion rockets nearby in the last few decades" and use it as evidence to support "therefore, all the aliens that evolved before us are dead and civilizations die out quickly."

1) Why?

2) If they use computer simulations, eventually they'll want more computers.

3) Interstellar colonization being rare might be true, but interplanetary civilizations not existing seems implausible.

4) I concede that point.

[Rhadamantus]

Basically, Rhadamantus, you're using a variation on the "apes or angels" thesis.

What it comes down to is that if we go exploring the galaxy in search of intelligent life, we should expect to find that most intelligent species have existed much longer than us. If they're still around, they'd be far more advanced than we are. Another handful of species would have existed significantly less time than us.

But a species much younger than us would be pre-technological in a state of hunter-gatherer life, or its equivalent adapted to an alien ecosystem. In other words, "apes."

And a species much older than us would presumably have technology that makes ours look like rocks and sticks. In other words, "angels."

And you then go on to ask "where are all the angels? I cannot see them from my front porch as I would expect. They must all be dead."

...

The problem is that this chain of reasoning makes some very shaky assumptions.

One is that the "angels" use technology that looks the way we expect it to look. For instance, thirty or forty years ago we assumed that our radio signals would blanket the night sky and aliens could easily find us that way. That was when we relied on broadcast television. Someone invented cable, and now we transmit a lot less information and energy into the sky. We cannot rule out the possibility that highly advanced aliens simply use different technologies, unknown ones or simply unforeseen ones. Technologies that are harder for us to detect at long range.

Another is that there may be practical limits on the advancement of the "angels" that allow them a happy and stable existence without producing huge technological signature. If the average intelligent species decides to relax on one planet and does not massively colonize its own solar system and isn't loopy enough to start dismantling planets for Dyson spheres... we might have a much harder time noticing them, than if we assume they will do all that heavy construction.

And of course a third is that if we're looking for angels by observing something that has a transient signature by nature (i.e. huge fusion rockets, which are only visible while firing), we may simply be looking in the wrong time, or the wrong place.

Ok, the fusion rockets is not the best argument. Though I would argue that we should point telescopes at stars to try to see if there are fusion drives going off there.
However, interstellar colonization is defenitely possible, at speed 3% that of c using modern technologies (Orion drive). We don't do that on Earth because of the limited test ban, but would every civilization do so? Because if one did, they could spread very quickly, and we should find remeants.

[Eternal_Freedom]

Where do you get the idea that interstellar expansion is possible "very quickly" using Orion drives? Even at 0.03c it will still take about 120-130 years to reach Proxima from Earth, if these aliens are roughly similar to humans in terms of lifespan, that's too long for a mission without either a generation ship or large-scale cryopreservation. Yes, they could do it, but they may well decide it's infeasible with their current technology, or just not economically viable for them.

Incidentally, why do we always seem to assume that alien civilisations will be pushing tot he stars at the fastest possible rate? Don't you think the alien civilisation would have economic issues, political factors etc?

Maybe all the human-or-better-level civilisations within a few hundred light years decided (as humans largely have) that manned spaceflight/interplanetary travel simply isn't worth it.

[The Romulan Republic]

Where do you get the idea that interstellar expansion is possible "very quickly" using Orion drives? Even at 0.03c it will still take about 120-130 years to reach Proxima from Earth, if these aliens are roughly similar to humans in terms of lifespan, that's too long for a mission without either a generation ship or large-scale cryopreservation. Yes, they could do it, but they may well decide it's infeasible with their current technology, or just not economically viable for them.

Incidentally, why do we always seem to assume that alien civilisations will be pushing tot he stars at the fastest possible rate? Don't you think the alien civilisation would have economic issues, political factors etc?

Maybe all the human-or-better-level civilisations within a few hundred light years decided (as humans largely have) that manned spaceflight/interplanetary travel simply isn't worth it.

Possible.

And a tremendously depressing thought.

I think that we'll get their eventually, though, if slowly, barring some sort of global calamity in the interim that prevents it. Their are enough people that do think space travel is worth it that we're probably going to keep gradually expanding our capabilities- private enterprise will likely get us as far as Mars eventually, if nothing else. And the more we build those capabilities, the easier and more affordable its likely to be to go one step further.

[Broomstick]

The key thing for interstellar travel will probably be large, self-contained, self-sustaining habitats that can comfortably house people on multi-generational journeys.

[Simon_Jester]

For all we know, humans may actually be unusual in respects that affect our likelihood of colonizing.

Imagine a species of intelligent dolphins. They might exist millions of years without inventing tools.

Imagine a species whose reproductive cycle is intimately tied up with the climate and biomes of their home region. They might find it very difficult to colonize unfamiliar environments, and while they can maintain artificial habitats, their instincts are likely to point towards conserving what they have rather than spreading out into the universe making more stuff like home.

Imagine a species whose social instincts are so much stronger than ours that they can't bear to act alone or in small groups, making space exploration intensely difficult. Conversely, imagine a species with social instincts weaker than ours that can't cooperate on advanced technological prospects.

1) Why?

2) If they use computer simulations, eventually they'll want more computers.

3) Interstellar colonization being rare might be true, but interplanetary civilizations not existing seems implausible.

4) I concede that point.

Basically, aliens may not build massive fusion rockets if they do not choose to launch massive interstellar colony expeditions. For traveling around your own solar system there are likely to be more efficient choices, or choices that downscale better for smaller applications.

And as to the "live in computer simulations" issue, what makes you think their population will continue to grow without limit? If nearly everyone's physical body is basically a meat accessory that lets them enjoy their VR lives, it's entirely possible that a population control regimen will be in place, with most people not having a strong impulse to have lots of kids once VR starts subverting their instinctive drives.

If population doesn't grow completely out of control over the long haul, there is little incentive to do massive interstellar colonization and the ever-popular huge fusion rocket.

[Note, I'm not saying this is a desirable end state for a civilization, but it's certainly a realistic one]

Ok, the fusion rockets is not the best argument. Though I would argue that we should point telescopes at stars to try to see if there are fusion drives going off there.

Well sure; it's simply that we can't take absence of a highly specific type of evidence as evidence of absence.

However, interstellar colonization is defenitely possible, at speed 3% that of c using modern technologies (Orion drive). We don't do that on Earth because of the limited test ban, but would every civilization do so? Because if one did, they could spread very quickly, and we should find remeants.

It may be that the most nuke-happy civilizations tend to blow themselves up with nuclear wars (or irradiate their homeworld until no one can live there). Alternatively, it may simply be that just because it's possible to get a colony ship to the nearest star in 200 years doesn't mean everyone, or even most people, do so- and that doing so once is not a guarantee that your species will choose to do so again and again.

[Alyrium Denryle]

Ok. First of all

Rhadamantus the multiple consecutive posts need to go. You can incorporate multiple replies by doing the following:

Code: Select all

[quote="other user name"] TEXT[/quote] (make sure you use the quotation marks)
Your reply
[quote="second other user name"]TEXT[/quote]
Your reply

repeat ad infinitum

This has been a public service announcement from the SLAM mod.

That having been said, I am going to explain some things to you.

Fuck.
Right. This means that habitable planets are around 10% of star systems. If that's true, then there should be tens of billions of habitable planets in the galaxy. Since life seems commons, there should be billions of civilizations that have existed, and hundreds of thousands around now. There aren't. Therefore, either we can't find them, life is difficult, or intelligent life exterminates itself easily.

There are a lot of reasons why this is not necessarily true.

For starters being tidally locked does not necessarily mean that the planet does not have a magnetic field or is not rotating. Tidal locking means that the speed of orbit matches the speed of rotation. This does not preclude a magnetic field around the planet as long as the core of the planet remains molten.

Now, some radiation will get through anyway with a flare star, but that is OK. A molten core means tectonic activity and tectonic activity means that life probably started like it did on our little ball of dirt. Around deep ocean vents. As long as that is true, life can evolve resistance to radiation. We have living things alive on this planet right now that can happily withstand--completely unprotected mind you--the radiation doses of 500k-1.5 million rads through a combination of polyploidy and rapid DNA repair mechanisms. So long as the early stages of life evolve in a protected environment like deep ocean vents, natural selection will take care of the rest.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Why would they?

Here, let me show you some math.

Rd = ( 17.8E6 * sqrt( Ms*As*Isp*(1-Nd)*(1-Ns) ) )

where:

Rd = maximum detection range (kilometers)
Ms = bogey spacecraft mass (tons)
As = bogey spacecraft acceleration (G)
Isp = bogey drive specific impulse (seconds)
Nd = bogey drive efficiency (0.0 to 1.0)
Ns = bogey "stealth efficiency", i.e. fraction of waste energy which can be magically shielded from enemy detectors. (0.0 to 1.0)

So lets take the Space Battleship Yamato weighing in at ~70000 tons, it uses a Magneto Inertial Fusion drive that can accelerate it to 20 Gs for some horrifying reason. Specific impulse is 5140 seconds, we will call Nd .5 and NS 0.0

( 17.8E6 * sqrt( 70000*20*5140*(.5)*(1) ) )

This puts the detection distance at 1.06E12 km, Proxima Centauri is at 4.13E13, so that honking big fusion drive would not be detectable at earth from Proxima Centauri.

I dont know what the parameters are on the fusion drive cooked up by Zubrin, but...

If a civilization has moved on from building fusion drives, then they have either fallen back or used something more advanced. More advanced stuff would be more easily detectable.

That is not necessarily true. An anti-matter torch drive for instance (dear god) would be governed by the same equations. We might detect it as stray photons from a gamma ray burst, or because of the inverse squared law, we might not detect it at all. Unless they were detonating multi-terraton antimatter bombs as part an antimatter orion drive, we are unlikely to detect that. Our telescopes and detectors just dont have the resolution to distinguish that from the background noise.

Ok, the fusion rockets is not the best argument. Though I would argue that we should point telescopes at stars to try to see if there are fusion drives going off there.

Why would we see them? If we point telescopes at star systems, any fusion drive will get lost in the glare of said star unless it somehow manages to outshine the star itself by a significant margin.

[Adam Reynolds]

It is also possible that the small things also play a notable role in the evolution of intelligent species that might then go on to form space faring civilizations. Here are two possibilities that come to mind:

Timing in terms of geologic history. If humans had evolved significantly earlier, there would have been no reserve of fossil fuels to jump start industrialized civilization, which is obviously required to develop space travel.

The presence of a moon similar to ours allowing strong tides, which then allows life to begin in the oceans and eventually evolve on land, which is likely somewhat required to develop proper tool use.


This is besides the quite likely truth that going outside of a single solar system is generally not worth it. Even if space travel itself is worth it, once one has developed fusion power, there really is no reason to leave given the incredible resource abundance of our solar system.

[Alyrium Denryle]

Timing in terms of geologic history. If humans had evolved significantly earlier, there would have been no reserve of fossil fuels to jump start industrialized civilization, which is obviously required to develop space travel.

And how exactly would that have occurred? Sapient life would have to evolve VERY fast for that to be a thing, because oil is largely the product of plants being crushed by millions of years of high pressure. For there not to be significant oil reserves, sapient species would have had to evolve in the Devonian or earlier.

The presence of a moon similar to ours allowing strong tides, which then allows life to begin in the oceans and eventually evolve on land, which is likely somewhat required to develop proper tool use.

Tides are not a requisite for life, or a movement of that life onto land. Period.

[Rhadamantus]

Where do you get the idea that interstellar expansion is possible "very quickly" using Orion drives? Even at 0.03c it will still take about 120-130 years to reach Proxima from Earth, if these aliens are roughly similar to humans in terms of lifespan, that's too long for a mission without either a generation ship or large-scale cryopreservation. Yes, they could do it, but they may well decide it's infeasible with their current technology, or just not economically viable for them.

Incidentally, why do we always seem to assume that alien civilisations will be pushing tot he stars at the fastest possible rate? Don't you think the alien civilisation would have economic issues, political factors etc?

Maybe all the human-or-better-level civilisations within a few hundred light years decided (as humans largely have) that manned spaceflight/interplanetary travel simply isn't worth it.

Yes, they might have economic issues. However, a orion mission to Alpha Centauri would cost less than a trillion dollars. For a society even somewhat more advanced than us, that's cheap for the opportunity to colonize an entire solar system.

[Esquire]

No, it's not. That trillion dollars would have to come from somewhere - we can't even all agree that people deserve to not starve to death, and you want to spend a huge sum of money on something that will accomplish exactly no practical aims and will take centuries?

[Kingmaker]

For a society even somewhat more advanced than us, that's cheap for the opportunity to colonize an entire solar system.

Why bother? It will most likely be an extremely long time yet before the Solar System is tapped out, and it's not like the Alpha Centauri colony is going to be sending stuff back in a timely fashion (if at all), so the investment is a total loss from the perspective of the the investing entity. A sufficiently wealthy civilization might do some interstellar exploration out of curiosity, and you might even have eccentric space quadrillionaires doing colonization as a 'because we can' vanity project, but I don't think it's a given that interstellar colonization will be of huge interest.

[EnterpriseSovereign]

For a society even somewhat more advanced than us, that's cheap for the opportunity to colonize an entire solar system.

Why bother? It will most likely be an extremely long time yet before the Solar System is tapped out, and it's not like the Alpha Centauri colony is going to be sending stuff back in a timely fashion (if at all), so the investment is a total loss from the perspective of the the investing entity. A sufficiently wealthy civilization might do some interstellar exploration out of curiosity, and you might even have eccentric space quadrillionaires doing colonization as a 'because we can' vanity project, but I don't think it's a given that interstellar colonization will be of huge interest.

This just highlights the desperate need for FTL travel, cracking that particular nut would have massive ramifications for all involved. No-one with any degree of sanity is going to send a manned mission outside of the Solar System with mere sublight capability since by definition you're going to be spending decades (at minimum) covering interstellar distances.

OTOH, high-sublight speeds would make interplanetary travel far more feasible, since even sending probes takes years to get anywhere with what we have today. The sheer gains to be made from making exploration of the Sol system would be extraordinary.