Robert Zubrin and Dana Andrews took a failed attempt at formulating Bussard Ramjets, and turned them into magsails that are quite efficient at slowing down interstellar craft. They also don't suffer from the rocket equation. Using these in conjunction with tethers could take care of much of the manuvering at the endpoint of an interstellar trip.

I love your videos, can I get your thoughts on a few questions? If these laser highway relays are putting off enough thrust to push a ship, wouldn't they also need to be firing in the opposite direction to keep their position? That would at least double the energy spent on any of the relays. Also, how would the lightsail ships dissipate their heat? Getting hit with a laser that could light up continents would fry anything in seconds, not to mention getting hit with it for years/decades at a time.

@Eric. the reflectance needs to be high. That may also be a reason to go with microwave. Aluminum is over slightly over 90% in the visible range. upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Image-Metal-reflectance.png/400px-Image-Metal-reflectance.png Aluminum would heat up a lot with a blue/red laser. A kilogram of TNT is about 4 megajoules. So if you have 99% reflectance, 1kg sail and 400 megawatts it should be blowing up like TNT in under a second. Not sure how fast a thin film radiates heat. On the bright side the radiant heat could add some propulsion. The stations generating the laser beams probably have to dump a lot of heat. Isaac's generator was 0.1% efficient so 99.9% is going somewhere else. So the station should be able to radiate much more thrust than the thrust from the laser.

@chris pearson, 15:09 Included in video.

Couldn't the mass driver just be circular around the originating star and then release the payload at a tangent towards the destination star? This way you can accumulate as much speed near a large power source almost like a very large particle accelerator but with more substantial payloads. Then just use the relays to slow down the vessels as they approach their destination using lasers and light sails. I can see such a scheme bootstrapping itself giving the initial vessels just enough speed and fuel to eventually slow itself down to stop at their proper place in the relay. Perhaps you can integrate this with the star lifting schemes and drive some of the stars' hydrogen along the relay path. Or else mass drive fuel to the relays at a slower speed and have the equivalent of tanker trucks dropping off fusion fuel to the relay stations on an ongoing basis. Alternatively, you can set up these relays at habitats in Oort cloud objects when available. Also, I think that instead of a light week between relays it would be better to have more, smaller relays so that the vessels can communicate to the forward relays and give them better targeting information. I think that a 24 hour cycle with 12 hours powering the laser to slow down incoming vessels and another 12 hours waiting for a signal from the vessel to confirm the "hit" and provide new velocity and location information would drastically reduce the risk of directing the lasers in the wrong direction. While waiting In the meantime you can either target other incoming vessels (perhaps from the opposite direction) or redirect the power to the needs of the local habitat.

Well, almost everything is a delicacy there :)

There used to be a planet there with the best ice cream in the multiverse, but a treaty with the local sentient arachnoids ruined it... :/

In my cycle raw salarian liver was a true delicacy

LOL!

I understand the inhabitants of the Gastronomy Sector are dedicated humanitarians - their greatest desire is to serve humans... Try their Soylent Green ice-cream.

ClarkThech lightspeed

If you just believe hard enough...

No I cannot imagine. The nice thing about research and travel is the surprise.

Solar sails

But needing to take years, if not centuries, to travel between stars has a beauty of its own. I honestly can not really explain it. It is melancholic but also reafirming at the same time.

SnowToad haha true man

I broke the 123

Look, I don't HATE organics. It's just that they're made out of matter. And matter can be made into paper clips.

Human: make me a handful of paperclips. Grey goo: *constructs a planet-sized hand filled with paperclips*

This is why we get them to make chocolate icecream instead, it's not as problematic to have a planet made of the stuff.

Aaand now I'm thinking of that idle-ish game where you eventually make an entire universe out of paper clips. I'm not kidding, it's a thing. :)

@@robinchesterfield42 that's the joke...

I can never think of space pirates without picturing some cheesy Tom Baker era Doctor who costumes or something kinda Guardians of the Galaxy flavored. :)

I wish Centuri (Centuri Engineering Company, the model rocket company, which owns Estes Industries, on paper [Centuri Corp.]) would be put back in business, perhaps as a "division" of Estes; I loved their futuristic kits. Don't feel bad, though; many people mistakenly called them *Centauri* Engineering. :-)

I got an idea 💡

"You will remember this standardized galactic day as the standardized galactic day where you almost caught space captain Zorg Sparrow!"

Yep. Welcome to the club.

@@slevinchannel7589 Are you randomly commenting on every comment? And Isaac is talking about INTERSTELLAR spaceships, not some random rocket.

Fish Santiago Almost every example he's made makes me think he's from the future

Regardless, I will leave that comment at 100 likes...

I hope so, because sadly i lost almost any hope.

lol... cutest time traveler?

John Everett WE were lucky to live on this era

Are you out of the closet?

John Everett - I know bro, hope we are still around to see them get to Mars. SpaceX or NASA?

@@EmileAI Oh without question.

wouldn't it be funny if our society just crashed and then during the chaos a asteroid just killed us all and instead of seeing humanity become a spacefaring race you just see us all die a painful death

If there were only a few hundred at the time, probably last august or July, I remember in September I had 800 and was terribly smug about that. I'm glad to know the channel's stayed fresh and interesting that whole time. :)

True dat

Robert B the channels growth is absolutely insane, I subbed late August and the channel has just exploded in the last few months!

I've only just discovered the channel and have been binge watching earlier vids. Blown away by the quality of content and having great fun daydreaming on future fun times for our descendants (the lucky buggers). Pretty sure I'll be paraphrasing Robert B in a year's time, reminiscing on 42k subs when the channel blows up!

It was thanks to reddit that I found these videos and I am so happy, they are wonderful.

Logan Hester Stars are made out of plasma, not rock. /s

Get your game on, go play!

Maracachucho Hey now!

RockStar? GTA creators?

I think I speak on behalf of humanity when I say we love you, Isaac.

Alexrider02 One thing I loved about the Mass Effect series was the codex, which took the fictional inventions, like "mass effect/element zero", and applied them thoroughly, examining all the side uses and ways that they would be realistically applied in order to create a fleshed out, believable world.

I've still never played any of the ME games. I've heard good things, I just haven't gotten around to them yet.

Good time to give the ME series a try, newest installment is out in a month or two. I actually just started replaying the trilogy with that in mind. One of the few FPS games I enjoy.

Good to hear you recommend it, I'll have to keep an eye out if they go on sale. Love your videos, if I had a job at the moment you are one of the few channels I would love to support on Patreon, just because your videos are always so compelling. Keep up the good work. :D

Alexrider02 I think Mass Effect 2 is still free on Origin

Nice nod to Douglas Adams (specifically to his book; The Hitchhiker's Guide to the Galaxy)

That time might be worth it. The solar system will still be around and the galaxy will still be young.

me too

Even Nobel winners can be wrong :) Actually they frequently are, or maybe just get recorded more. It is interesting though how many of these concepts have been kicking around for a decade or more and just not got popularized.

Well they have to be wrong sometimes, because they contradict each other. I would be surprised if there aren't Nobel winners who have said the opposite.

Millions of years...? After googling a little, it turns out that guy is a theoretical physicist. 150 years ago, he would be arguing that heavier than air flight is impossible.

what if you do: - a launch from moon - do a fly-by at the sun with chemical/electrical populsion - come back to moon, rendezvous with your solar sail and people - then fire some lasercanons from there what speed could you reach?

right... 't Hooft is quite the pessimist. We will find a way...definitely. May be not as humans though.

Static position lasers aren't terribly dangerous, especially a solar powered one, very big target, if someone hijacks or hacks one, you just use another laser to blast it.

Andy Falconer we have nukes anyway, what's the problem?

AlHoresmi The EMP from an orbital nuclear strike would probably wreck havoc with electronics both on the ground, and of a bunch of the surrounding satellites. Also, unlike a laser, any blast would probably scatter debris and make a sizable region of orbit dangerous/unuseable.

lasers counter ballistic missiles

Putting the laser on the other side of the moon makes it worse. No one on earth can see what you are doing. Obviously we have light weight/cheap mirrors that can reflect the laser so shooting around the moon is not much of a challenge. You could, for example, have the mirrors hang out around earth/moon Lagrange points 4 and 5. Is a much shorter range than 1 light week. Could tin foil hats replace camouflage as standard military gear?

indeed

Badumm tsh. But seriously though, you missheard Isaac. He said they are a mess! That's why the starsail tries to get away from them.

So does that mean an infrared photon is a hot mess?

Wesley Howard - man, I think they call that blasphemy😹

They have inertial mass. It's different than rest mass. Anything moving at or near the speed of light increases in mass. Unlike anything with non-zero rest mass, photons' mass doesn't approach infinity as they approach C.

Thanks! It should hit some time today I think, about a month and half earlier than I expected when I last guessed at 40k.

Thanks!

Your welcome!

Lukegear Ageed! Thursday mornings have quickly become one of my favorite parts of the week :) Also, as a fellow Luke, I'm curious if you were also named after Star Wars; I figure my dad liked the idea of always having an easy, go-to joke for life haha

Curiously, there's a mildy interesting story behind it, I'm brazilian, so due to portuguese language my name is actually the latin variant "Lucas" which gave rise to the name "Luke" in english. And, indeed, my dad used to joke around with how the names are so close to each other, and used to call me "Lucas Skywalker" when I was little, when he introduced me to Star Wars. So the joke stuck around in my mind, and since I love science, tech, and knowledge in general, I figured that I would use the "gear" as part of my name, since it is the symbol of technology and mankind's capacity to shape the world, thus my internet nickname and logo were born :)

Lukegear Cool! I'm technically a "Lucas" as well, as my mom wanted something more "presidential" (whatever that meant, it's hopefully not applicable now :P ), but I usually go by Luke haha

Lucas fits even better. Since of course Luke Skywalker = Luke S = Lucas (George)

Yeah and considering its speed I'm not terribly sure what that's really going to accomplish, its a very small object that will zip through the area very fast, I'm thinking bigger local telescopes will get more done, but I still love the idea.

Isaac Arthur I think it'll be more of a proof of concept and initiative to develop the necessary engineering and tech, and could probably be supplemented to push larger, more useful objects later

Isaac Arthur According to the breakthrough starshot team themselves, the pictures their craft take would be the equivalent of a 300km- diameter telescope in LEO. If their optimistic-looking timeline actually works out, sending a probe might be more productive. They could also use the same tech to send a slower, higher mass space telescope to the sun's gravitational focal point, but they haven't outlined that as part of their mission. And of course their giant laser array system itself could function as a telescope as well.

No kidding? Well I stand corrected then, I trust them to have done their numbers better than my off the cuff guess :)

Isaac Arthur What are your off-the-cuff numbers, by any chance? Their claim is here: breakthroughinitiatives.org/Target/3 Of course, there is the point that a 300 km telescope can do more than just look at alpha centauri (and other nearby star systems). I think using the breakthrough starshot technology for gravitational lens missions will work better for this reason, but an interstellar mission is always going to get more publicity than a gravitational lens project.

Thanks Andrew, this is another one of those episodes I was worried might be too niche or obscure.

It looks like it will be a fun series

lol

ZUUL42O haha

@@isaacarthurSFIA came here to say this.

Close enough for solar power there too, though considering the distances it would probably be easier to build closer to the sun as part of an initial Dyson-up.

I was thinking mostly in terms of the number of bodies, which would allow for omni-directionality. No matter what angle you were coming or going, there could be a laser propeller somewhere in your vicinity. Make a nice relay from the inner to the outer system. Maybe repeat it in the Kuiper belt too. But yeah, we'd need them all over the place - orbiting the sun, the Earth, the moon, the asteroids, and all the outer planets and their moons too.

I disagree, because you are going to have your speed limited by the centripetal force you would have to provide. Perhaps you might be able to do that by adding a large charge to your craft and adding huge magnetic fields or something, but if you're still going for the ring on a belt around the sun idea it would be better putting it in the Kuiper belt or even the Oort cloud, you need less centripetal force then.

Unstable Audio Productions A Major Lazor

Probably giant huge solar powered clocks belching out the time from statites hanging over stars, that's how I'd do it.

Isaac Arthur Basically the exact same idea, scaled up haha. Do you think the doppler shift of pulsar timings could provide precise enough positioning for a cheaper, generalizable alternative/supplementary data source?

Potentially, but you can build an atomic clock more accurate than a pulsar and you can pick your own frequencies and emit very precisely on them. It also gives people a definite fix point to pick up on lower power signals like news, stocks, and traffic, as it were, but odds are each relay would actually have its own GPS calibrated very precisely off each other and the home systems

Is it possible to correct an atomic clock for the "delay" at relativistic speeds between the stationary beacon and a moving ship? In my understanding, the clocks of both the sender and receiver would have to run identically. It seems like ships themselves would have to correct for time dilation and the time it takes light to reach them, since even clocks on satellites around earth drift away from earth time.

Isaac Arthur Very true! I suppose in the case of interstellar highways they would be unnecessary. I guess I was probably more considering distant travel/exploration using other methods where the angular span of such "Galactic Positioning System" structures became increasingly minute, and therefore less accurate, something like that using existing natural references could provide some supplementary information to refine what you got beamed from back home. I also hadn't considered that each relay could very easily supply such information as part of the beam anyways. Thanks again for continually providing new ideas and expanding my framework of understanding :)

Ian Moone The sail would have to be incredibly smooth, probably more so than the best telescope optics. Otherwise, even just microscopic surface roughness would reflect the beam (which is slightly conical anyways) at differing angles, causing it to diffuse into a much wider cone quite quickly. You'd have to be incredibly, ridiculously close for the reflection to still be tight enough to do any damage :P

eh point it at Australia.

TheMasonX there's advantages to focusing it, if possible. If you can direct the laser back to a mirror near the laser source, then you can bounce the beam back and forth multiple times to get more momentum from the same light. There are serious engineering challenges, naturally.

Yep, not something to use arriving in or departing a Dyson swarm.

Even if the sail or laser become miss aligned, you wouldn't necessarily have a death star scenario because the energies are off by many orders of magnitude. If you watch at about 5:30 where Isaac uses F=P/c he derives P=1.5GW. Giga watts is billions of watts - so the order of magnitude is about 10^9. But if you look into how much energy it'd take to blow up a planet (I quickly found this: scifi.stackexchange.com/questions/90193/what-is-the-wattage-of-the-death-stars-superlaser ) that guy says, "this puts the Death Star's power output at approximately 6.67 x 10^26 Watts, at minimum." However he assumed that the beam, at the given power output, only lasted 3 seconds. If we used our 1.5GW beam for long enough (and since in theory we are probably generating the beam from solar output, and or fusion we can use it indefinitely) at some point you'd have the 2*10^27 joules they used to calculate 10^26 watts. Watts is joules per second so solving for time we get s=J/P => s= (2*10^27 joules)/(1.5GW. Giga watts) which is about s=(10^27)/(10^9)= 10^18 seconds. Considering that 10^18 seconds = 3.1 × 10^10 years worst case scenario the solar highway pointed at a planet for a very long time would do surface damage at best, but you'd have to have the makers of the highway disappear from galactic maintenance pretty much forever, otherwise they'd just realign things.

Quite a lot, especially if you're using a big mag sail an AU across or something.

Isaac Arthur So our initial highway setup ships might cary a remarkably large drag chute to aid in deceleration near stars, save fuel that way...

at 10% _c_ , I wouldn't trust in solar counterthrust. Besides, the larger the sail, the more damage it will likely have sustained in transit. Need some sort of onboard or preceding installation for slowdown thrust.

You're very welcome, thanks!

Most artillery pieces shoot sub-sonic, projectile speed isn't so important when you're doing indirect fire. And no railgun I know of can get into space, but we'll be talking about that in the next month or so in the Upward Bound Series.

How would she know that?

as soon as the consciousness splits the two are different entities.

They probably wouldn't mind the expanded experience of many selves and occasionally catching up with a branch having interesting experiences in another solar system.

indeed they could get sensory data from their experiences but it won't have been them making the choices unless the life form went into suspended animation until it received the telemetry. And there is the small detail that there is another life form running around that now has rights of its own.

I think for a few tens of thousands of years ones copies would still say "That's what I would have done, Bro!" .. "Could not have said it better myself!" when reviewing each others life.

"It can be done now under our current understanding of physics," is very different from, "it can be done now." Something like this would bankrupt the human race in millions of times over. It'll probably be centuries before we have the infrastructure and capability to do this.

I don't think it's as far off as you might imagine. Once we have the AI revolution, highways like this could easily be manufactured as fast as we could get the equipment there.

I agree wholeheartedly!!

And maybe stop funding those crazy military ideas concerning space based lasers to shot down enemy ICBM? ;) (Yeah, I see the problem here - quite many space technologies are being seriously funded only because of their possible military application. I somehow doubt that if one was redirecting military budget it would end up in R&D., I can think of quite a few pressure groups that would be higher or any political priority list than some astronomers)

Humanity are adolescents, we are just finding ourselves, give it another 100 years and we will be on the right track i think

Welcome to the channel, I'm glad yo're enjoying it!

Isaac Arthur Thank you!

Thank you!

Thanks Stewart!

A few others have mentioned that too, and I do seem to be getting less comments on it in newer episodes, but I can't say I've noticed myself.

Thanks Hugh!

Hugh B. Long fancy meeting you here Hugh :)

:) Not Thursday? I'd probably fall over dead trying to do 2 a week

Thursday I work all day so most of the time, I watch it friday morning. Anyway, thanks for your hard work, I'm sure just doing one a week is hard enough as it is. All your videos are high quality, deeply researched stuff.

Thanks Luke!

Thanks Tanner, I try to keep them info-dense but fairly straight-forward at the same time, and am never sure how well I do the juggling act.