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Fast Radio Bursts from Extragalactic Light Sails
- kangnkodos 10y agoIf we are receiving the FRBs, the focused beam must be pointed towards earth. So the spaceships with light sails must be headed in the direction of earth. Get ready for the invasion!
- throwaway7645 10y agoOr the FRBs are built using the least efficient beam design ever constructed ;)
- Gravityloss 10y agoI think the beam spreads a lot because 1. the wavelength is relatively long, because you want a sparse microwave sail 2. the antenna is of finite size 3. the distance involved is intergalactic
- gwern 10y agoShades of Larry Niven.
- M_Grey 10y agoProtectors or Kzin? Either way, we're done.
- pavel_lishin 10y agoWell, it'll take them awhile to get here. There's still time to start putting rail-guns on asteroids for purely mining purposes, or giant laser arrays on Mercury - just for moving ships around of course.
- CWuestefeld 10y agoMoties, he's thinking of, as in "The Mote in God's Eye".
- rikkus 10y agoOr reflecting off the sail. Or diffracting around it.
- misja111 10y agoNo because they are only short bursts. If they were guiding a spaceship in our direction then we would observe them as a constant source of light.
- eunoia 10y agoOnly if they were aiming at where we are now, which doesn't make sense. They would have to aim the craft at where we are going to be in X years. X being the duration of the voyage. Come to think of it, even if they were aiming directly at where we are now I would assume the light source would still be occulted regularly by everything between us and them.
- downrightmike 10y agoThey could be checking for stellar drift.
- yazaddaruvala 10y agoGotta remember, if we are seeing light intentionally or unintentionally, they pointed these sails to our current position, almost X years in the past. Where X is the distance in light-years.
- colanderman 10y agoWell that's silly. How do they plan to decelerate?
- valarauca1 10y agoIf you project a large magnetic field the extra-solar ionized gas (intergalatic, between stars) can exert a fair amount of drag. A lot of people talk about bussard collector (magnetic scope for hydrogen/helium) to power fusion. But instead of collecting gas use it as a drag chute.
- evgen 10y agoYou have two sails in concentric rings that are connected, with your craft attached to the outer ring. When you want to decelerate you disconnect the two rings and and tweak the reflection of the inner ring to be somewhat outward focused and give the inner ring a little push. As it moves forward the energy bouncing off the inner ring is directed backwards to the outer ring, which slows. As long as the inner ring reflect more energy backwards (and to the outer ring) than the outer ring is getting from your source the outer ring slows down. Really hard to describe, but easy to draw. First proposed by Robert L. Forward.
- Darthy 10y agoImages here: http://www.lunarsail.com/LightSail/rit-1.pdf http://www.lunarsail.com/LightSail/rit-1.pdf (pages 5, 7 and 8).
- yazaddaruvala 10y agoWhy do you think its "man"ed? It could be an intra(inter)-galactic ballistic missile (i.e. no deceleration);
- Arizhel 10y agoI for one welcome our new lightsail-powered overlords.
- throwaway7645 10y agoDidn't read the article, but it's always fun following these lines of thought. We have no evidence of life outside earth, but darn it...we can't be the only ones here...I mean we can, but that just doesn't sit well with me. I wonder if almost any civilization would end up using lightsails powered by beams or if many skip it in favor of some other technology.
- adrianN 10y agoI like to think that black hole propulsion is the way to go https://arxiv.org/abs/0908.1803 https://arxiv.org/abs/0908.1803
- saalweachter 10y agoFusion candles. https://www.schlockmercenary.com/2003-08-03 https://www.schlockmercenary.com/2003-08-03
- felipemnoa 10y agoIt will probably be something similar to this [1] that allows humans/aliens to travel to distant worlds. As per my limited understanding, nothing can move faster than light in space-time, but it seems that it may be possible for a space-time wave to move faster than light. We would just ride that wave. [1] https://en.wikipedia.org/wiki/Alcubierre_drive https://en.wikipedia.org/wiki/Alcubierre_drive
- AnkhMorporkian 10y agoThat requires the existence of exotic matter, something that really isn't known to exist at all, and it'd be pretty surprising if it did. Pretty much all FTL schemes require some exotic thing that's unlikely to actually be feasible in our universe.
- felipemnoa 10y agoThe bending of space is possible though. We could figure out how to bend space in a different way. Think about it, alchemists were trying to figure out how to turn lead into gold. We now know how to transmute an element into gold, although not economically. Science is till pretty young. I wouldn't rule out something similar to the Alcubierre Drive for space travel.
- kator 10y agoMaybe I'm just crazy but there are a list of things I hope we figure out in my lifetime, and extraterrestrial intelligence is right up there in the top ten.
- M_Grey 10y agoI think that's one of those things that's better to have been born well after (assuming a good outcome) or born well before (assuming a bad outcome). It's really hard imaging the transition as anything other than misery and chaos.
- fsloth 10y agoUh, why would proof of extra terrestrial intelligence induce misery and chaos?
- pauletienney 10y agoWell, humankind does not have a great trackrecord of humility, harmony with its environment, acceptance of change and difference.
- ge96 10y agoJust a random thought, your reality is made up of your environment. Ever imagine being taken out of the Earth and being in space. Suddenly, no bills, no kids, no debt, no whatever. Also nothing else either. You'd probably be dead haha. Still, if there are aliens, it's kind of dumbfounding like "Huh... am I free now?" Is there something greater than this government that controls me? Not saying the government does, I make my own dumb decisions that create my own misery. It would be a slap to the face though, look at these aliens that can choose to anihilate us or enslave us. (bad case). Just my thoughts, I'm nobody, no credentials, this is purely opinion/current mental maturity haha. I don't know it's always depressing to me how massive space is, 40 years traveling at 50-150,000mph and the voyager just leaves our solar system hahaha. Crazy. (my numbers might be off depending on reference but that idea of 4 years of 9,000,000 feet per second) to get to the nearest start (dot in the sky) holy christ. edit: haha holy crap it's approximately 984 million feet per second for like 4.6 years edit: voyager speed ~36,000 mph, not sure how long that took to build up to that speed.
- jlebrech 10y agoI've often thought to ask whether we'd even come up with technology to pick up fast moving objects in space heading towards us even before we have the capacity to travel at those speeds ourselves. we've always observe things in nature and then replicated them, if we saw something move faster than light that would advance our technology even if it's just by knowing it exists elsewhere.
- kator 10y agoMore than once I've been in a meeting where someone said "But competitor A spent 1 Billion dollars building that". And I would quip back "And now we know it can be built and it won't take a billion dollars to do it". I agree, the real value is know something is possible from there all things related make more sense and many decisions can be made based on that one fact.
- undersuit 10y agoWhen I saw this new article start popping up yesterday it reminded me of the book Starfarers by Poul Anderson. Strange radiation signatures are detected in space, scientists figure out it is alien tech, and then figure out how to reverse engineer it.
- openasocket 10y agoextragalactic travel seems to be a really dangerous and difficult prospect. The journey will take millions of years (assuming no FTL travel), and there's basically nothing in between. Even if your species is immortal or something, there's serious risks. You need to bring everything to need for the journey, including energy, because there aren't any stars you can stop at along the way to gather solar energy. You'd have to be very careful planning things so you don't wind up stranded partway.
- pavel_lishin 10y agoI think that when they say "intergalactic", they're not referring to ships crossing between galaxies - they just mean that the signals we're detecting (which may be light-sail 'engines') come from outside the Milky Way. The ships themselves could just be cruising between stars within those galaxies.
- openasocket 10y agoWell, now I feel dumb. I should have read beyond the abstract before commenting!
- riskable 10y agoIf you're effectively immortal why would you want to hang around the same place forever? You wouldn't. In fact, you might hope for "something to happen" along a 100,000-year trip just to shake things up a bit! Also, don't assume that alien life is like ours. It could be many orders of magnitude more efficient and in all likelihood isn't even biological in nature if they've reached the point where a million-year journey is feasible. It could just be a bunch of AIs constantly re-making themselves from resources they pass by as they coast through the universe. They might not even have a destination! They could literally just be a bunch of machines that "live" in space. Floating around from place to place, grabbing resources from asteroids as they go by. Lastly, in regards to energy: Why assume solar? Once you've reached speed you're not going to slow down much. Just leave the sails open to protect your craft from debris. I'd also expect a nuclear battery in such a craft to power on-board components. There's plenty of radioactive material in space to draw from for renewal as well. You also don't have to worry about disposal! Just toss it towards the nearest star system or asteroid belt and get a bit of thrust out of the action :)
- jbmorgado 10y agoI'm as Astronomer. I think it's very interesting to read about these kind of scenarios in novels, but I don't think they have a place in a scientific publication. We are researchers, we try to explain the universe by improving our understanding of the physical processes that lie behind what we observe. The moment we bring aliens or gods into the picture to explain something for which we don't have an answer, we are doing a disservice to science.
- pavel_lishin 10y agoIt doesn't sound very scientific to automatically discount an act of an intelligent being as the source of some phenomenon.
- fusiongyro 10y agoWhat sounds more scientific to you: "we don't know what causes effect A" or "we postulate elves are causing effect A"?
- pavel_lishin 10y ago"We don't know what causes effect A" isn't science, it's just a statement that we don't know something. If the elvish hypothesis proposes some experiments for testing and disproving it, then yes - it sounds more scientific.
- fusiongyro 10y agoYeah, but you don't have experimental design for the alien intelligence "hypothesis." This is just emotionally satisfying drivel. There's nothing unscientific about not having a hypothesis when more information is being gathered. The paucity of data on FRBs makes any hypothesis right now almost worthless. We don't even know for sure that the majority of FRB data we have are from non-terrestrial phenomena. FRB occurrences at Parkes correlate strongly with lightning storms near the observatory. But sure, it's probably angels or little green men. Why not. That's a hypothesis, you're doing science Jimmy!