Proxima Centauri

[Orionblamblam]

While generation ships tended to be panned by sci-fi writers (seriously, how much novels do you read when generation ship voyage did NOT ended up in total disaster?),

it's not unreasonable to assume that generation ships will encounter serious difficulties. We're generally talking about flight times measured in centuries if not millenia; human societies are barely able to hang together for that long on earth with essentially unlimited resources. For a generation ship to do that it will need the sort of social regimentation to be found in "Brave New World" or "1984."

 

[chimeric oncogene]

Also, generation ships are a lot more mass to throw at fractions of c (I assume you're not going to take more than 400 years to get to AcA). My guess is that you end up spending similar amounts of energy (assuming self-replicating factories massing under a few thousand tonnes are possible, of course) if you shoot a ten-million-tonne space habitat at 1% c vs. a hundred-thousand-tonne seedship at 10% c.

They're good, I guess, if you're exhaust-velocity limited, but I tend to bet on lasersails simply because all the expensive equipment is stored at home.

Lasersails can also be used to build "railway track" for a pick-up-your-propellant-as-you-go approach, although that has serious problems of its own.

 

[Dilandu]

My guess is that you end up spending similar amounts of energy (assuming self-replicating factories massing under a few thousand tonnes are possible, of course) if you shoot a ten-million-tonne space habitat at 1% c vs. a hundred-thousand-tonne seedship at 10% c.

Probably, but seedships are... more problematic in several other areas. They required a very autonomous AI, capable of handling not only the possible problems in travel, not only adapting to the conditions of the designation points, but also the complex task of raising the "zero" generation of colonists. Which is probably not the area, in which AI's - notorious for the ability of self-learning programs to make weird logical decisions, which are rather hard to understood - not exactly shine. You hardly would like the paperclip maximizer in charge of colony...

 

[Dilandu]

You might read Kim Stanley Robinson's Aurora. It describes the voyage of a generation ship and what could happen if the future generations on the ship decide they are not as gung ho as their parents were about being born and having to live off Earth. Their parents got to decide that they wanted to take the risk of leaving home base forever. Their children didn't get that choice and assuming they will adapt to living in a ship in space could be a real deal-breaker.

Well, I must point out, that there were a lot of examples of perfectly stable societies, that existed for generations in near (or complete) isolation. Again, this depend on the size of the ship. O'Neil colony ship would have a lot of internal volume to use. O'Neil fleet - a large group of O'Neil colonies, flying together - would essentially have a total space of a small country. Which should make social problems quite easier.

Again, there is a serious bias against generation ships, based mainly on the assumption that society onboard must be a transplant of one of Earth existing ones (presumably western-type liberal democracy), instead of being specially designed for the mission purpose.

 

[Orionblamblam]

, based mainly on the assumption that society onboard must be a transplant of one of Earth existing ones (presumably western-type liberal democracy), instead of being specially designed for the mission purpose.

One would be expected to ask why anyone would go to the bother of building and outfitting a generation ship in order to send someone else's society. It's kind of like the argument between terraforming worlds to be comfortable for stock humans, or genetically engineering humans to fit disparate worlds. The logical conclusion must be to fit the worlds to the species; by diversifying humanity into vsarious forms that can't live with together, you've built in a the perfect recipe for genocide. Similarly for generation ships. If you build a society specifically to fit indefinitely on a generation ship... why do they give a damn about the colony world you're shooting them towards?

 

[Dilandu]

One would be expected to ask why anyone would go to the bother of building and outfitting a generation ship in order to send someone else's society.

Because it's kinda obvious, that society on the designation planet would evolve anyway into quite different form of original Earth one. Chances of finding Parallel Earth type of world is extremely slim; even on most hospitable exoplanet, conditions would require special efforts for humans to survive.

 

[Orionblamblam]

Chances of finding Parallel Earth type of world is extremely slim;

That's why you terraform, and build space habitats with Earth-like environments. What the frak is the point of colonizing a world that stock humans can never visit... and that the modified colonists can never leave? if you just want the place for it's resources, send down the robots to mine it bare, and ship the raw materials up the gravity well to either built artificial habs or terraform other worlds.

What to do with a world like Venus? Such a place *could* be terraformed, with considerable effort. But perhaps another approach was in L. Neil Smith's "The Venus Belt:" A sufficient industrialized spacefaring civilization could turn Venus into an asteroid belt... a belt which could be used to create *millions* of habitats, each capable of containing entire civilizations. With that kind of power, creating some sad offshoot subspecies seems more cruel than anything.

 

[Dilandu]

Hm!

Dyson was talking about a sort of far-future pure fusion system. Probably more akin to Daedalus. Orion used known atom bombs which were pure fission; the bombs had a *lot* of "dead weight" including the casing and electronics and the explosives and just about everything, ending up with a pusher plate made out of tungsten. To get starship performance, you'd need a bomb that was little more than a ball of deuterium that underwent nearly 100% fusion. A hell of a big step.

I just thought some idea... what if we do NOT put the drive charges on Orion/Medusa-type probe? What if we pre-seed the trajectory, along which Orion/Medusa would accelerate with drive charges, launched in advance - by some type of mass driver, for example?

I.e. the starship would "chase" the beforehand launched charges. When starship is near to drive charge, the charge would orient itself & blast, sending a streak of particles to push the starship a bit more. Thus we could make starship itself very small, light, and cost-effective, while using nuclear charges available now.

 

[chimeric oncogene]

Probably, but seedships are... more problematic in several other areas.

That's the railway track approach. Handy when you're exhaust velocity limited, but like I said, many many other logistics issues and firing accuracy issues and travel time for the railway track, and the fact that the railway track may not be easier to lay than... shooting a seedship out into the deep black. OTOH, accuracy is going to have to be excellent for lasersails anyway.

Seedship =/= zeroth generation colonist; I was thinking more along the lines of 1,000 people cooped up in a minuscule habitat for 10-40 years together with a self-replicating factory unit. Much easier to design systems for 20-40 years of travel than rely on a few generations of colonists, you pack spare parts instead of raw materials and expanded fabrication plant, and no need for training of personnel, rules, population trims, etc. over several generations.

 

[Dilandu]

That's the railway track approach. Handy when you're exhaust velocity limited, but like I said, many many other logistics issues and firing accuracy issues and travel time for the railway track, and the fact that the railway track may not be easier to lay than... shooting a seedship out into the deep black. OTOH, accuracy is going to have to be excellent for lasersails anyway.

Well, it seems like something doable on our current level of technology & not overwhelmingly costly (still enormously costly, of course). Especially for miniature probes.

Seedship =/= zeroth generation colonist; I was thinking more along the lines of 1,000 people cooped up in a minuscule habitat for 10-40 years together with a self-replicating factory unit. Much easier to design systems for 20-40 years of travel than rely on a few generations of colonists, you pack spare parts instead of raw materials and expanded fabrication plant, and no need for training of personnel, rules, population trims, etc. over several generations.

Ah, understood. Sort-of hybrid approach - generation ship with minimal reasonable population, with the large supply of frozen sperm/ovas? Yes, it seems reasonable; albeit the majority of "pure" seedship advantages are lost here.

 

[chimeric oncogene]

generation ship

The shorter travel time is precisely to minimize the problems of a generation ship. The margins for failure for education and training of the next generation should be somewhat looser with infinite mass and a big industrial base upon arrival at say ACA.

It's not a generation ship. A 50-70 year old crewman lives to walk on ACA, and help raise the first generation at AcA. I'd prefer crew in the 20 year old range, and travel times under 20 years, for that reason. I do not expect crew born in flight. I'm pushing it by expecting crew to have kids at 40, but it's definitely doable. I'd actually prefer 10 year travel times, which would pretty much completely solve the problem, but greatly reduce target selection and increase power requirements... scratch that. If we can't make it on ACA, there's not much point trying tau ceti, and we'll have scaled up the lasersail array by then.

The 1,000 number is estimated from the minimum possible population size of ~500 necessary to sustain a population without dying from inbreeding. Lower populations are entirely survivable if you send follow up spacecraft or use embryos and duty kids.

 

[Dilandu]

It's not a generation ship.

Well, essentially it is, since the zero generation would not be the main active force by the time of arrival, but I understood your logic. Let's call it "kindergarten" ship.

A 50-70 year old crewman lives to walk on ACA, and help raise the first generation at AcA. I'd prefer crew in the 20 year old range, and travel times under 20 years, for that reason. I do not expect crew born in flight. I'm pushing it by expecting crew to have kids at 40, but it's definitely doable. I'd actually prefer 10 year travel times, which would pretty much completely solve the problem, but greatly reduce target selection and increase power requirements... scratch that. If we can't make it on ACA, there's not much point trying tau ceti, and we'll have scaled up the lasersail array by then.

Agreed with logic, albeit I still not sure that laser-sail is the best solution. I'm kinda worried about large sail ability to survive impact erosion being deployed at relativistic velocities.

The 1,000 number is estimated from the minimum possible population size of ~500 necessary to sustain a population without dying from inbreeding. Lower populations are entirely survivable if you send follow up spacecraft or use embryos and duty kids.

Er, we could actually have much less than 1000 without follow-up crafts, just by storing a large supply of frozen sperm from widely diverse donors. If I recall correctly, the frozen sheep sperm was found to be perfectly viable after 50+ years of cryogenic storage. The problem about population size would be more around population buildup after arrival; too small crew would experience serious troubles establishing colony, and could be seriously threatened in case part of the population would die in some disastrous incident.

 

[Dilandu]

One more point. Assuming that we could reach 0,1c, the total working cycle of Proxima Centauri manned mission would still took more than a century. The model (data calculated roughly, rounded, ect.):

Year 0: Launch of unmanned flyby probe to Proxima Centauri - to investigate, would the system actually warrant more close (and costly) exploration.

Year 43: The flyby probe made flyby through Proxima Centauri system, gathering as much data as possible & sending it toward Earth.

Year 48: The data from flyby probe reached Earth.

Year 50 (very optimistic): Launch of unmanned deceleration-capable probe to Proxima Centauri - to make a throughout exploration of the planetary bodies, investigate them on the possibility of colonization, and gathering as much data as possible.

Year 93: The second probe went into orbit around Proxima Centauri and start the exploration program.

Year 98: The second probe gathered enough data to fulfill all mission requirements. Data send to Earth.

Year 102: The data from the second probe reached Earth. The preparation for the manned expedition starts.

Year 112 (assuming it would took roughly ten years to figure out the details of expedition based on the data from second probe, design & develop all required equipment, train personnel, ect.) Launch of manned expedition.

Year 155: Manned expedition reached the Proxima Centauri system.

I.e. from the first launch of flyby probe to the first men on Proxima Centauri - a century and a half, and this assuming rather optimistic course of action. If, for example, detailed exploration of planetary system would require launch of additional probes (for example, if something like life forms would be found, thus requiring more specialized equipment for their study), the scale would slide toward two centuries or more.

 

[chimeric oncogene]

One more point. Assuming that we could reach 0,1c

Depending on your rocket design... if it were a lasersail, I'd try to go to at least 0.2-0.5c, to return mission data in a reasonable timeframe of <20 years instead of something along the lines of forty years. It might be hard to do, depending on the specifics of the tech, or you might just sacrifice the Proxima mission to focus a laser on the ACA probe for twice (?) as long with a bigger lens.

Harder to do with an antimatter rocket, but theoretical max exhaust velocity from that is 0.3c (atomic rockets). So again, depends on the tech base.

Hardly kindergarten. I was thinking a mixed crew of 20-year old grad students and 30-odd year old PhDs/grizzled astronauts (or Mormons or whatever). The payload is the younger people, a truckload of embryos (those won't last very long either) and their reproductive systems and cultural knowledge. Try to get to target in under twenty years, preferably ten.

Breakthrough starshot's gunning for twenty years too. Forty years is too long for useful data. They wanted to send Cassini to Uranus (it would have been a twenty year transfer), but it was a silly idea and cost ludicrous amounts of money to keep the probe running for data... in twenty years, if the probe didn't break along the way.

But yeah, whole program turnaround could be a century, easy. I don't think you'd send the industrial base with the main colony, TBH. Have a smaller, more expendable expedition set up an industrial base first, and then send the first colonists. And you're going to want a mission to test the deceleration stage before you load it up with an industrial base and astronauts. Whole program's running on a century-long timeline, easy.

Another implication I really like about superlaser arrays for lasersails is... the geopolitical implications. 50 petawatts worth of solar-powered superlaser (that's what my old napkins say you need for a 100,000 tonne ship, 10,000 tonne payload-ish at 0.5c I think) is not quite something the Earthers are going to trust the Martians, or worse, those dastardly Jovians, with. Sure, the big things are fragile as frick, but could they zap every ship in the system before they get blown up?

Breakthrough Initiatives

breakthroughinitiatives.org

 

[edwest4]

I have some knowledge of the history of technology. From the Wright Brothers' first flight to the first atomic bomb took less than 45 years. I am predicting a breakthrough in faster than light travel. It is the only practical option.

 

[Dilandu]

Depending on your rocket design... if it were a lasersail, I'd try to go to at least 0.2-0.5c, to return mission data in a reasonable timeframe of <20 years instead of something along the lines of forty years. It might be hard to do, depending on the specifics of the tech, or you might just sacrifice the Proxima mission to focus a laser on the ACA probe for twice (?) as long with a bigger lens.

Yes, but above 0,1c problems of interstellar dust & radiation start to rise pretty fast... you would need heavier and heavier bumpers. Of course they are also solvable, but in conjunction with large laser sail (which is impossible to hid behind a bumper), the situation quickly start to be problematic.

Harder to do with an antimatter rocket, but theoretical max exhaust velocity from that is 0.3c (atomic rockets). So again, depends on the tech base.

Agreed here.

Hardly kindergarten. I was thinking a mixed crew of 20-year old grad students and 30-odd year old PhDs/grizzled astronauts (or Mormons or whatever). The payload is the younger people, a truckload of embryos (those won't last very long either) and their reproductive systems and cultural knowledge. Try to get to target in under twenty years, preferably ten.

Well, I meant "kindergarten" in therms of older peoples training younger generation (because "schoolship" is just too cliched! )

But yeah, whole program turnaround could be a century, easy. I don't think you'd send the industrial base with the main colony, TBH. Have a smaller, more expendable expedition set up an industrial base first, and then send the first colonists. And you're going to want a mission to test the deceleration stage before you load it up with an industrial base and astronauts. Whole program's running on a century-long timeline, easy.

Make sense, yes. We could launch several cargo ships with equipment & supplies (and probably even robotic miner ships, to gather materials & water ice from Proxima asteroids & comets) while manned expedition is still in development.

Another implication I really like about superlaser arrays for lasersails is... the geopolitical implications. 50 petawatts worth of solar-powered superlaser (that's what my old napkins say you need for a 100,000 tonne ship, 10,000 tonne payload-ish at 0.5c I think) is not quite something the Earthers are going to trust the Martians, or worse, those dastardly Jovians, with. Sure, the big things are fragile as frick, but could they zap every ship in the system before they get blown up?

Well, it's a bit outside the context) But I like your style)

 

[Dilandu]

I have some knowledge of the history of technology. From the Wright Brothers' first flight to the first atomic bomb took less than 45 years. I am predicting a breakthrough in faster than light travel. It is the only practical option.

Edwest, we are not even sure that FTL is possible, not to mention practical. We barely started to experiment with the idea of artificial warping the time & space, and we still not sure how to avoid the time travel paradoxes associated with FTL. It may be perfectly possible, that FTL may actually work only slower-than-light (like Alcubierre bubble; seems that it is not very practical as faster-than-light engine, but could work quite nice as relativistic one) - or required slower-than-light missions to build the FTL route (like wormholes or Krashennikov tube).

 

[Orionblamblam]

I just thought some idea... what if we do NOT put the drive charges on Orion/Medusa-type probe? What if we pre-seed the trajectory, along which Orion/Medusa would accelerate with drive charges, launched in advance - by some type of mass driver, for example?

The idea is not new. However, the typically suggested approach is to - somehow - lob a string of millions of deuterium pellets. Your starship is more akin to a Bussard ramjet, but rather than trying to scoop up the thin haze of hydrogen in interstellar space you just scoop up pellets. the trick of course is to accurately shoot pellets with a dispersion of presumably only a few dozen meters over a distance of perhaps a few lightyears.

 

[edwest4]

One of the most prominent scientists of the time period stated he did not believe powered human flight would be achieved. If it weren't for some scientists like Nikola Tesla, important aspects of our 'modern' world would not have appeared. Imagine precisely positioning magnets to create a "wiggler" where a beam of light could be reshaped into a wave. The primary requirement is to discard current thinking and devise a way to achieve light speeds. I realize this is a non-trivial problem but the will to try must be there.

 

[Dilandu]

One of the most prominent scientists of the time period stated he did not believe powered human flight would be achieved.

If you means lord Kelvin, he did not claim that its physically impossible, he merely stated that steam engines are too inefficient to be useful for aircraft. And he was basically right in that matter. He does not took into account the rapid development of internal combustion engines, but they were not some new physics either - they were just a new technology, with great potential.

If it weren't for some scientists like Nikola Tesla, important aspects of our 'modern' world would not have appeared.

Nah. They would appear, maybe a bit later. There were numerous scientists working on the same problems.

. Imagine precisely positioning magnets to create a "wiggler" where a beam of light could be reshaped into a wave.

Er... wiggler (undulator) used magnets to undulate the beam of high-energy charged particles, thus emitting powerful synchrotrone radiation. The beam of charged particles is NOT the light (i.e. not photons).

The primary requirement is to discard current thinking and devise a way to achieve light speeds.

The primary requirement is to find if it is ever possible. I may wish for a device that would turn the bricks into twice their mass Persian kittens (they are super-cute!), but while rebuilding brick into kitten is at least theoretically possible, doubling the mass is not. There may be some clever way around (like dragging mass from parallel universe), but there may not be either (especially considering that we still have little proof that parallel universes exist). Also, dragging mass from the other universe could create some problems like change in vacuum energy density value, which would lead to catastrophic consequences in both universes. So while brick-into-double-kittens-mass-inator is a neat idea, it may not work, it get into conflict with basic laws of matter conservation, and seriously, isn't its more practical to just buy a kitten from breeder?

 

[Dilandu]

The idea is not new. However, the typically suggested approach is to - somehow - lob a string of millions of deuterium pellets. Your starship is more akin to a Bussard ramjet, but rather than trying to scoop up the thin haze of hydrogen in interstellar space you just scoop up pellets. the trick of course is to accurately shoot pellets with a dispersion of presumably only a few dozen meters over a distance of perhaps a few lightyears.

Well, my exact idea is somewhat different - it is more like a line of legs that kick the starship when it fly nearby) By using the complete fusion charges - not just pellets - we could pretty well solve the accuracy problems, by just giving each charge some reaction control & low-power thrusters. The bomb would automatically correct its trajectory, and when starship fly nearby would aim & blast.

 

[Desertfox]

There are two ways I see to solve the FTL problem. 1) Solve the issue of energy required for an Alcubierre Drive (i.e. War Drives) or 2) Figure out how to manipulate gravity. We know how the first one works, but there are major engineering hurdles to overcome, unfortunately we haven't figured out gravity yet. Bussard Ramjets are great but they are limited to only around 0.8C.

But for an actual developed project to go to Alpha Centauri in less than 40 years: Project Daedalus

 

[Dilandu]

1) Solve the issue of energy required for an Alcubierre Drive (i.e. War Drives)

Er...

Firstly, we still do not know HOW to create the negative mass matter. We could calculate how much energy it would took, but we still have no clue how to use this energy to get negative mass in practice.

Secondly, there are doubts that Alcubierre drive would actually work as FTL. It seems that it (may) works well on sub-light velocities, but on FTL things became... more complex.

Thirdly, it's unclear how exactly Alcubierre drive would solve the cause-and-effect violations that FTL could present.

2) Figure out how to manipulate gravity

And?

, but there are major engineering hurdles to overcome

It is possible that warp field experiments might actually give some clues how to contract/expand time space, but currently they are in very-very early stage.

 

[Desertfox]

Technically, Alcuberrie drives are sub-light so there shouldn't be any FTL cause-and-effect violations.

If you can manipulate gravity you can also manipulate mass, which helps with the "infinite mass as one approaches 1c" problem and makes any form of propulsion more efficient. Manipulating gravity might also lead to breakthroughs with dealing with warp drives and wormholes. And finally if you can use gravity directly, it would be a form of massless propulsion, without a theoretical speed limit (other factors could limit it). Is it possible? I don't know, but the possibilities are endless.

 

[Dilandu]

Technically, Alcuberrie drives are sub-light so there shouldn't be any FTL cause-and-effect violations.

Well, as long as they are kept sublight - yes, but then how they are suppose to -

solve the FTL problem.

?

If you can manipulate gravity you can also manipulate mass, which helps with the "infinite mass as one approaches 1c" problem and makes any form of propulsion more efficient. Manipulating gravity might also lead to breakthroughs with dealing with warp drives and wormholes. And finally if you can use gravity directly, it would be a form of massless propulsion, without a theoretical speed limit (other factors could limit it). Is it possible? I don't know, but the possibilities are endless.

Wormholes are probably the best shot, but they still most likely required sublight ship to move one end to target system.

Is it possible? I don't know, but the possibilities are endless.

Well, the question is more "wouldn't it change the vacuum energy density"?

 

[chimeric oncogene]

massless propulsion, without a theoretical speed limit (other factors could limit it).

That's not how relativity works. As you get closer to the speed of light, time speeds up for you, but not outside observers. The universe literally gets shorter, allowing you to get to targets very fast. But an observer on Earth will just see your spaceship get shorter, and your clocks run slow. From your persepctive, it might take say, a year to get to Proxima because the universe shrank for you, but to an observer on Earth or Proxima, you'll have taken nearly exactly four years (if Proxima is a hypervelocity star, moving with respect to Earth, they'll get a slightly different clock time from Earth with a few hours-days difference).

Causality. Relativity. FTL. Pick any two.

FTL travel is time travel, as far as we can tell. If you like pesky things like cause and effect, you can't have FTL travel. Going faster than a photon is just unphysical. The photon doesn't change speed no matter how fast you go - the universe warps space and time around you and the photon to make it so the photon's speed as measured by you stays constant. Also, there's no universal timebase, and everyone's point of view of what is happening when is equally valid, no matter how fast they are travelling, as far as we can tell (that's the "relativity" part - my buzzard ramjet is standing still, it's the rest of the darned universe moving past me at 0.99c).

New physics might help us, but we see no evidence of it yet, and it still has to shoehorn relativity's test results into the new physics framework. Relativity is all around us, in every GPS satellite and JDAM strike (relativity based calculations are used to calibrate the atomic clocks far up the gravity well, you'd get bigger errors if you ignored relativity). It's as real as the ground beneath your feet. Relativity affects how starlight flies through the universe, so we can reasonably say it hold true everywhere.

I again direct you to the beginner's guide to relativity: the FTL travel page on the wonderful atomic rockets website.

Faster Than Light 1 - Atomic Rockets

www.projectrho.com

Faster than light travel might turn out to be possible. But it's not quite clear how, and I wouldn't bet on it.

 

[jeffb]

Interesting bit of perspective from a physicist /mathematician:

Sabine Hossenfelder - Is faster than light travel possible

 

[chimeric oncogene]

Interesting bit of perspective from a physicist /mathematician:

Sabine Hossenfelder - Is faster than light travel possible

So... causality is overrated? Okay.

 

[Dilandu]

FTL travel is time travel, as far as we can tell. If you like pesky things like cause and effect, you can't have FTL travel. Going faster than a photon is just unphysical. The photon doesn't change speed no matter how fast you go - the universe warps space and time around you and the photon to make it so the photon's speed as measured by you stays constant. Also, there's no universal timebase, and everyone's point of view of what is happening when is equally valid, no matter how fast they are travelling, as far as we can tell (that's the "relativity" part - my buzzard ramjet is standing still, it's the rest of the darned universe moving past me at 0.99c).

I'm no expert here, but I recall that - theoretically - wormholes (if they could be made traversiable), could be arranged in such way in relations to the point in time, that causality would not be affected? I.e. one end of the 10-ly long wormhole is in present, the other is 10+ years in future, and as long as you travel it only one way, the causality would be fine, because you would arrive at the other end after the light from the starting point?

Of course if you are trying to return along the same wormhole, the situation would became... complicated.

 

[Foo Fighter]

Bending space, worm holes and time travel. Wonderful idea's but they really need a TARDIS or two.

Not to mention the multiverse theory.

 

[Dilandu]

Bending space, worm holes and time travel. Wonderful idea's but they really need a TARDIS or two.

Not to mention the multiverse theory.

IMHO, for the next 100 years we stuck with rockets.

P.S. And I also should mention, that even if FTL is possible, it would most likely NOT be cheap. Sending FTL expedition would be formidable enterprise, requiring enormous resources.

 

[Flyaway]

Relating to another nearby red dwarf. In some ways this sounds a better candidate for life.

Press release: Super-Earths discovered orbiting nearby red dwarf

International researchers led by University of Göttingen find multiple planet system orbiting Gliese 887

Gliese 887 is one of the closest stars to the Sun at around 11 light years away. It is much dimmer and about half the size of our Sun, which means that the habitable zone is closer to Gliese 887 than Earth’s distance from the Sun. RedDots discovered two more interesting facts about Gliese 887, which turn out to be good news not only for the newly discovered planets but also for astronomers. The first is that the red dwarf has very few starspots, unlike our Sun. If Gliese 887 was as active as our Sun, it is likely that a strong stellar wind – outflowing material which can erode a planet’s atmosphere – would simply sweep away the planets’ atmospheres. This means that the newly discovered planets may retain their atmospheres, or have thicker atmospheres than the Earth, and potentially host life, even though GJ887 receives more light than the Earth. The other interesting feature the team discovered is that the brightness of Gliese 887 is almost constant. Therefore, it will be relatively easy to detect the atmospheres of the super-Earth system, making it a prime target for the James Webb Space Telescope, a successor to the Hubble Telescope.

Information for the Media - Georg-August-Universität Göttingen

Website of the Georg-August-University Göttingen

www.uni-goettingen.de

 

[Dilandu]

Relating to another nearby red dwarf. In some ways this sounds a better candidate for life.

Quite interesting - and in reasonable range.

 

[Justo Miranda]

Classic book

 

[Flyaway]

Relating to another nearby red dwarf. In some ways this sounds a better candidate for life.

Quite interesting - and in reasonable range.

It just looks a far more settled star, well it is these days compared to Proxima Centauri.

 

[Airborne2001]

Seems that planers are much more characteristic for star systems than their absence.

Now the problem is how to took even a glimpse on them from close distance...

Breakthrough Starshot will (hopefully) achieve the task of seeing them up close.

 

[Orionblamblam]

FTL travel is time travel, as far as we can tell. If you like pesky things like cause and effect, you can't have FTL travel. Going faster than a photon is just unphysical. The photon doesn't change speed no matter how fast you go - the universe warps space and time around you and the photon to make it so the photon's speed as measured by you stays constant. Also, there's no universal timebase, and everyone's point of view of what is happening when is equally valid, no matter how fast they are travelling, as far as we can tell (that's the "relativity" part - my buzzard ramjet is standing still, it's the rest of the darned universe moving past me at 0.99c).

I'm no expert here, but I recall that - theoretically - wormholes (if they could be made traversiable), could be arranged in such way in relations to the point in time, that causality would not be affected? I.e. one end of the 10-ly long wormhole is in present, the other is 10+ years in future, and as long as you travel it only one way, the causality would be fine, because you would arrive at the other end after the light from the starting point?

Of course if you are trying to return along the same wormhole, the situation would became... complicated.

A wormhile that allows instantaneous travel from Earth to Alpha Centauri and back would not violate causality. Where things get tricky is when you have wormholes where one end has been transported at high relativistic speed and then brought back to the other, so that the ends are now at different times. Travel one way would theoretically send the traveller into the future; the other way, into the past. Sending something into its own past would have interesting issues for causality. But sending something faster than light would not.

 

[Dilandu]

Breakthrough Starshot will (hopefully) achieve the task of seeing them up close.

Let's hope! Even such small probe would be able to give us an order of magnitude more data, than we could obtain from Earth.

 

[Rhinocrates]

A wormhile that allows instantaneous travel from Earth to Alpha Centauri and back would not violate causality. Where things get tricky is when you have wormholes where one end has been transported at high relativistic speed and then brought back to the other, so that the ends are now at different times. Travel one way would theoretically send the traveller into the future; the other way, into the past. Sending something into its own past would have interesting issues for causality. But sending something faster than light would not.

That's the premise of Stephen Baxter's novel Ring. The crew of a starship, called the Great Northern (a reference to Brunel, one of Baxter's heroes) spend a millennium accelerating to and decelerating from near C carrying one end of a wormhole. The crew start with advanced longevity, but even that has its limits and one faction takes the multi-generational approach. Of course things do not go as planned when they return.

 

[Justo Miranda]

Interesting bit of perspective from a physicist /mathematician:

Sabine Hossenfelder - Is faster than light travel possible

"Lost in Math"
In this "provocative" book (New York Times), a contrarian physicist argues that her field's modern obsession with beauty has given us wonderful math but bad science.

Whether pondering black holes or predicting discoveries at CERN, physicists believe the best theories are beautiful, natural, and elegant, and this standard separates popular theories from disposable ones. This is why, Sabine Hossenfelder argues, we have not seen a major breakthrough in the foundations of physics for more than four decades.

The belief in beauty has become so dogmatic that it now conflicts with scientific objectivity: observation has been unable to confirm mindboggling theories, like supersymmetry or grand unification, invented by physicists based on aesthetic criteria. Worse, these "too good to not be true" theories are actually untestable and they have left the field in a cul-de-sac. To escape, physicists must rethink their methods. Only by embracing reality as it is can science discover the truth.