Interstellar Travel Challenges

Interstellar Travel Challenges

One of the trickiest things about traveling
through the vast vacuum of interstellar space is that it isn’t a vacuum. So today we are going to be taking a look
at some of the difficulties involved in interstellar spaceflight and some features of spaceships
we haven’t discussed before for time constraints. We’ve looked at spaceships many times and
interstellar colonization too, but today’s topics take some time and were never absolutely
vital to the topic at hand. Here are those key topics we will be covering
today: 1. How fast Ships can go
2. The Non-Vacuum of Space
3. Collisions and Protection
4. The Shape of a Ship We will also be rejoining our Gardener Ship,
Unity, from the Life in a Space Colony Trilogy, you don’t need to have seen those episodes
to follow along with the discussion today but it saves some time to use them, and I’ve
grown rather partial to the ship. As a reminder, that ship massed in at a couple
hundred million tons, was a half a kilometer wide, and a few kilometers long. We’ve visually rendered it before but that
was always more conceptual then accurate. It had a crew of two hundred thousand when
it left Earth for the Tau Ceti system, and as it traveled at 10% of light speed it needed
120 years to arrive there. They had a lot of people born during the trip,
and also enjoyed massively extended lifespans, something we’ll discuss more next week,
plus they were receiving constant if delayed tech updates from Earth, and you can make
a lot of technological progress in a century. All of which meant they had more people when
they arrived than originally planned, and the technology to do the job better and with
less people. Many of the folks had adjusted to thinking
of the ship as home and been raised to think of colonizing solar systems as their life
purpose, and their worldview probably would have altered to view that as one of the greatest
accomplishments a person could labor towards. So it was no big surprise they decided to
continue their journey onward, planting colonies like seeds in a great big galactic garden
on an eternal journey toward the edge of the galaxy and maybe beyond. But the ship was not designed for that and
again they’ve got a century of technological progress since the ship was built, so they
decided to retrofit Unity before leaving Tau Ceti. They pick as their next destination 82 G.
Eridani, a system around a yellow sun that like Tau Ceti is a bit older, smaller, and
dimmer than our own Sun. It is more or less in the same direction Tau
Ceti is from Earth just a bit further along. Tau Ceti is 12 Light years from Earth and
82 G. Eridani is 20, but it’s about 12 light years from Tau Ceti being off at a bit of
angle. So it will take them as long to get there
as their first trip. They’d like to do it faster, and not need
120 years to cover 12 light years, the engineers say they can boost the speed to 20% of light
speed and a 60 year journey. However they are leaving with just a bit over
50,000 people so they still need to repopulate, but you don’t need a century to double or
quadruple your population especially when folks are not aging, they don’t die off
and they can keep having kids indefinitely. So they have no problem rapidly increasing
their numbers in a few generations, though generation ceases to mean anything in this
context, people are still having kids while their grandchildren are. They’re thinking they need a larger ship
too, not just a faster one. So we need to retool the ship, and the captain
calls a meeting of all the senior staff, ignoring for the moment that we have been assuming
this was a democratically operated civilian vessel who probably has an elected provisional
governor calling such shots. Same captain as before, she looks mid-twenties
but has been commanding ships since the old interplanetary vessel Hyperion so there’s
a couple centuries of experience there and her actual rank or rating is probably something
like Grand Admiral by now and she runs a ship that has more people in it than most top tier
navies have personnel. “How fast can we go?” She asks, “and why can we go faster now?” Her science officer speaks up and says that’s
not how this sort of thing works. We can go as fast as we want, the problem
is it takes exponentially more fuel to go faster. Every type of fuel that classifies as a rocket
has an exhaust velocity, how fast the stuff comes out the back. To get your ship up to that speed you need
for 63% of it to be fuel. That’s just how it is. And if you want to be able to slow down at
the end you need it to be 86% fuel. A ship that doesn’t need to slow down can
get twice as fast as one with the same fuel ratio, if you’re curious. If you want to get to double your exhaust
velocity, and not slow down, you need to be 86% fuel. If you want to slow down you need to be 98%
fuel, leaving only 2% of your mass for ship and cargo. If you want to get to triple that speed and
slow down you need to be 99.75% fuel, meaning you’ve got 400 times as much fuel as your
ship and its cargo. This is why we need rockets the size of tall
buildings to get ships the size of cramped apartments into space from Earth, because
the exhaust velocity of normal rocket fuel is considerably less than the escape velocity
of Earth even ignoring air drag. Getting to higher and higher speeds, compared
to your rocket exhaust velocity, requires exponentially more fuel. Their ship, Unity, used fusion, which has
vastly higher exhaust velocities than chemical fuels, usually estimated at a decent if low
percentage of light speed. The science officer says what has changed
is the new reactor designs from Earth let them achieve a more efficient degree of fusion
and results in a higher exhaust velocity, twice what it was before, we’ll say it used
to be 5% of light speed that the fusion products and leftovers flew out at before and now its
10%, that’s on the conservative lower and higher end of what we anticipate from a good
fusion drive. It also means that whatever the mass of the
ship and cargo is, when fueled up it will be about 50 times more massive than that,
and when it is done accelerating after some weeks or months to its cruising speed, it
will still be about 6 times more fuel than ship. The captain asks why not just go with a higher
ratio, even more fuel? After all, there is no shortage of hydrogen
available nor minerals to make the tanks out of, but that’s where the weapon’s officer
chimes in. It won’t work, he says, the current system
was designed to let them avoid collisions in interstellar space at 10% of light speed. By going twice as fast they will encounter
those objects twice as often and each carrying four times the energy and damage capacity. The science officer nods, and picks that up,
as he’s a bit of long-winded fellow who usually needs 20-40 minutes to get to the
point. He says the interstellar medium, all the gas
and dust between the stars, is quite thin, and most of it is hydrogen and helium gas
molecules, with the supermajority of the tiny amount remaining being very tiny motes of
dust containing a handful of atoms too. Those are not a problem, they act like radiation
and you just make your forward shielding a bit thicker. Ours will mostly be thin metal containers
full of fuel, hydrogen, because hydrogen is quite good at stopping radiation. What we have to worry about is things that
will make big holes, or even trash the ship, and since smaller particles are a lot more
common than bigger ones, we will run into a lot more of them. As a very loose rule when it comes to meteoroids
and micrometeroids there’s about an inverse relationship between mass and frequency. You expect to encounter stuff twice as massive
about half as often. Meaning that since everything is hitting us
with four times the energy, since we’re going twice as fast, something with a quarter
of the mass will do the same damage as when we were going half the speed. But those objects are now 4 times as frequent. To make it worse, since we need to vaporize
this stuff, and are going twice as fast, we will be encountering them twice as often,
so 8 times the frequency of stuff we need to shoot down, and we need to detect them
twice as far out to have time to react to them. We need to detect smaller things further away. Even worse yet, our little Local Bubble of
the galaxy is rather low in density compared to the galactic normal, which is about 10
times thicker than the interstellar medium is locally. This ship is not going to remain in that bubble
and indeed may pass into areas where the density is far higher, so best prepare now, while
we are making our ship bigger, faster, and better. Nor is the medium homogenous, you might go
through short patches where density is hundreds of times higher. Needless to say this all gets worse the faster
we get. At the speed we are going your typical grain
of sand weighing about a milligram would hit us like half a ton of dynamite, or around
a million times the energy of the average bullet. We can easily armor the hull against normal
bullets but these are pinhead sized objects that will penetrate rather deeply, leaving
small long holes. So even one just carrying that much energy
is something I’d rather not be hit by. Even as huge a target as Unity is, being half
a kilometer wide and tall, we still will only encounter about the equivalent of a bucket
of sand during a century long trip, in terms of cosmic dust and most of that will still
be too small to hurt us even at these speeds, but it is still enough that you might expect
to run into a grain of sand as often as once an hour and something the size of pea, which
would hit us like a small nuke, maybe once a month. But something carrying bullet force? That we would run into almost every second
and it would be only a handful of micrometers across, the width of the thinnest hairs. We need to see that tiny mote far enough out
to target it with a laser and vaporize it, and we are traveling 60,000 kilometers a second. Fast enough to travel from Earth to the Moon
in 6 seconds, fast enough to get to the sun in 40 minutes. Even computers need time to get an accurate
track on an object and aim, which usually involves moving something, then shoot and
hit something smaller than a grain of sand, though we’d probably use a wide beam and
go for overkill to compensate for positional uncertainties. Needless to say it takes a very powerful radar
system to get returns off something that small far enough away to help us. And it can’t be classic radar either, using
radio waves, because you cannot detect and track something smaller than the wavelength
of light you are sending at it. When you listen to a FM Radio channel, those
waves are about 3 meters long, so a Radar using them would have problems seeing and
tracking something the size of a person, even millimeter radar isn’t good enough for us,
not even microwaves are. We need infrared. Most types of dust and sand also absorb infrared,
often reflecting only a few percent of most wavelengths, giving us weak returns on our
radar. Handily many are very reflective of about
1-3 micrometers wavelengths, which in this case is what we need. So our Weapon’s Officer shakes his head
and says, “Look Captain, I think we can buff up our current systems to handle this
but I can’t make a lot of guarantees, maybe we ought to just stick to the same speed and
be happy we can carry a lot more cargo on a lot less fuel than before.” But fuel is cheap, she doesn’t really care
how much we use, any of a million small comets hanging around any solar system will have
plenty of hydrogen even without needing to try diving into gas giants to get fuel. So if there is any chance of safely shortening
the trips, she wants to take them, so she asks the Science Officer if there are any
other options. “Plenty”, he says, “But none of them
are pretty.” The captain says she doesn’t care if they’ll
take a lot of time to add on and maintain and he say no sir, he’s being literal, most
of the options just don’t conform to a nice looking stream lined ship from ancient science
fiction. She reminds him that they weren’t planning
to enter the ship in a beauty pageant and since they are going where no man has gone
before it is unlikely we’d encounter any anyway, and to get on it with it. So the first option is thicker armor, when
we’re done expanding the ship, its dry weight – its weight minus fuel for speeding up
and slowing done, is going to be around a billion tons of ship and cargo. The front cross section of the ship is about
200,000 square meters, so if we were making our armor out of big meter wide metal shelled
cubes full of hydrogen weighing a ton apiece, that would only be 200,000 tons out of a billion,
doing those five layers thick would only be a million tons. Tiny holes a few micrometers thick through
a centimeter of metal won’t leak gas fast. But over a century those would empty out easily,
and it’s awkward to patch and repair that area with all the radiation and micrometeors,
doable but kind of rough. So we could set it up like a conveyor belt. The front isn’t a big sheet anymore, it’s
the ends of thousands of little conveyor belts where the belt is made up of metal cubes full
of hydrogen, they rotate out and back in again and at the back side they get repaired, and
the belt widens out at the front to provide a few layers of overlapping armor and we slide
a new section forward whenever one takes an impact. Let the robots do the repairs in the rear
and keep some spares on hand. It hardly needs to be airtight just packed
close enough that almost nothing can slip through and we’ll have another layer of
more normal armor behind that. In fact we’ll store most of fuel up front
with habitation sections behind them. If a big collision happens and you need to
replace a big chunk of the assembly though, we have another option, we can shoot a small
solar sail ahead of us, itself just a micrometer thick. Just launch it and have it unfurl and act
as a temporary shield. Most stuff hitting it is going to slam right
through but fragment a lot or be deflected to the side just enough. It would act a bit like an umbrella. It would slowly drift back into the ship from
collisions and you could grab it then and drag it back inside and recycle it. Just a tin foil thick shield, even if we couldn’t
recover it the total loss of mass would be just a few tons out of a billion. The Captain asks why we can’t make that
foil-shield thicker, and the Science officer shrugs and says we can but we would be better
off having several of them ahead of us, spaced way out in front, not meters or kilometers
but whole light seconds ahead of us. She points out that the front one will just
be shoved back into the next one and so on until they get slammed into the front of the
ship. The Weapon’s Officer points out that they
will also get in the way of the ship’s radar and lasers, so it won’t work, but the Science
Officer shakes his head. We will place them far enough ahead that the
last one is just outside our minimum engagement distance, say a tenth of a second, more than
enough time for the ship to still locate, target, and fire on something that makes it
through. But it doesn’t matter, because we will keep
the shades strung out at the right distance by pushing on them with our own lasers, just
using them de-focused. They are a solar sail after all. And we will put sensor packages on them too,
adding a little weight but not much, and we can power those by having a few solar panels
we will target diffuse lasers on. When they get scrapped we will give them a
little side shove and let them drift back to us on the side and just snag it and drag
it in for recycling and repair. We’re going to put a lot of our lasers off
to the side ship, extending on big long thin telescoping antennas to keep them rigidly
locked to the ships and to provide power and data flow back to the ship. At the end of those will be a big laser and
radar, give us better detection and an angle to shoot at, also letting us more easily push
things to a side. Those telescoping antennae or arms won’t
be very massive. You have a dozen or so of them telescoping
out several kilometers to the side, radiating out like spokes on a wheel. If one gets damaged, and they might because
they won’t be much shielded, you just reel it back to the ship and repair it. Even if one gets snapped off it won’t drift
much or fast and you just shoot a grapple off to snatch it and reel it back in and repair
it. We can also shoot probes ahead of us, either
with their own fuel supply or pushed and powered by lasers, just expendable things to detect
stuff ahead of us and maybe even some weapons of their own. Even if they each weighed several hundred
tons we can deploy them on a regular basis. Indeed if we can mizro-size our fusion drives
enough we might want to send many out ahead of us to slow down and park on some comet
along the way to act as a fuel supply for a big radar and signal relay. Maybe even with lasers to help clear our path
for us, or just have them keep going and do a flyby of our path and destination. We’ve talked about using laser highways
as an ultra-cheap and fast way of traveling between existing colonized systems, and there’s
a lot to be said about laying that down on the original trip, this would be a good way
to get that started if we wanted to and had drives small enough. The Head of Maintenance complains they’ll
be constantly having to fix, build, and repair stuff but the Captain shrugs and points out
they are essentially a massive factory ship and always have to anyway, truth be told this
would seem to require very little personnel. She says all right, let’s do it, and the
science officer asks which system and she says all of them. They wouldn’t seem to interfere with each
other or need much mass or energy to operate, and they’ll go ahead and scale the ship
up too, but only in length, no point adding more cross-section to armor and defend. A ship twice as long doesn’t need twice
as much frontal armor if you’re are just making it twice as long, not twice as wide,
and that means the same amount of armor still guards twice as much ship. This is a key reason why when we discuss interstellar
ships on this channel I so often treat them as objects more akin to flying city-states
than a classic small crew ship of cast of half a dozen or even big ones like on Star
Trek with a crew of hundreds. We look at ships that are thousands of time
more massive than modern battleships or aircraft carriers crewed by hundreds of thousands if
not millions not because they need that much crew, they don’t, the ships would probably
mostly run themselves and just need a couple dozen people to make decisions and handle
unexpected events. Even then only if the ship didn’t have human-level
artificial intelligences on them, when in all likelihood they would, or something smarter. The same kind of automation that lets you
have ships that only need small crews or none at all to operate for decades trillions of
kilometers from home is the kind of automation that lets you build leviathans like we look
at quite cheaply. The problem with smaller ships, especially
tiny probes, are manifold, and I discussed those more in the Space Warfare episode, but
there they had the advantage of being harder to intentionally hit, but we’re not expecting
to be shot at, and by scaling up in size we benefit in a lot more ways. The small ships needs just as much radar,
just as many lasers, and so on. They also need some sort of power supply and
the fact of the matter is that even if you could make a fusion reactor very small, so
it would fit in a car, it is just the nature of such devices to be more efficient when
larger. There’s only a few realistic options for
going faster than fusion, we’ve discussed them before and they pretty much all require
using photons or maybe neutrinos as your rocket exhaust, if you have exhaust. One is laser-pushed ships, where being bigger
does help since your aft-mirrors for getting pushed on can be bigger allowing more distance
for those pushing lasers to target you. These let you get very fast, since the rocket
equation doesn’t apply, no fuel, but have the issue of slowing down, requiring either
slow down fuel or something like the interstellar laser highway we discussed in the Interstellar
Colonization episode back in Year 1. Another option is black hole starships, which
we gave a whole episode over to, and those had to be massive ships just by their very
nature, as we discussed there. The only serious option for a faster ship
then fusion can give you, while being smaller than an aircraft carrier and being able to
slow down is anti-matter. The main byproduct of combining matter and
anti-matter is photons, which obviously have an exhaust velocity of the speed of light. That doesn’t mean you only need an amount
of it as implied by the Rocket Equation to get near light speed though. We worked with speeds today and in the past
where could almost entirely ignore Special Relativity. At 10% of light speed you are getting a gamma
of just 0.5%, a meter long object is half a centimeter shorter, your clocks are running
slow by about one second every three minutes or about seven minutes a day and object need
just a little more energy to get to that speed than Classic Newtonian equations say. At twenty percent those effects have jumped
up to about 2%, a meter is 2 centimeters shorter, clocks lose about a second a minute relative
to Earth-normal. So a 50 year trip on Earth’s Calendar only
took you 49, and there’s a small but noticeable increase in energy over Newton. Even at 50% of light speed these effects aren’t
too huge yet, they jump to 15%. At 86% of light speed they double, even your
light speed exhaust velocity is straining to get you any faster and beginning to need
huge ratios of fuel to ship and cargo, and every object you hit whacks into you with
energy of its mass in anti-matter. At 94% it’s tripled, and 97% quadrupled,
quintupled at 98%, 7 times higher at 99%, 10 at 99.5%, and it keeps getting worse. Now at those speeds space really does have
enough drag that you want to be thinking about aerodynamic shapes too and nothing could push
a ship this fast as an onboard fuel you carried, not even antimatter at fuel mass ratios of
thousands to one, and you’ll need to constantly add in more energy just to maintain this speed
against that drag from space gas, and all but the tiniest motes of dust need to be vaporized
so they don’t smash your ship like a nuke. You’d probably need to punch those molecules
with a laser so hard they ionized so a magnetic field around the ship might shove them aside,
and that would need to be one heck of a magnetic field. And yes most ships probably would have big
magnetic fields because they will provide a little protection from anything carrying
an electric charge, and a decent fraction of the stuff in interstellar space is ionized
or will be when you’re zapping them with lasers, especially if those are in the Ultraviolet
or X-ray range of the spectrum. It won’t help with collisions but it will
decrease the ambient radiation from all the stuff too small to shoot. It’s why I don’t ponder faster than light
travel much, beyond its dubious nature as what is basically a mathematical gimmick,
it’s not like even getting near light speed is a real option because it requires obscene
expenditures of energy compared to just going half as fast and there are other things you
can do with that energy which are better alternatives than trying to get there a bit faster and
having to employ the kinds of radar systems that would glow like miniature suns and need
massive supercomputers just to track everything so you aren’t annihilated by a random grain
of sand. Those collisions and radiation begin becoming
the real problem and no cool space drive is going to magically make those go away. Your best bet for real interstellar travel
to places you’ve already been to is to have a long chain of fusion-powered laser relays
shoving ships around and constantly tracking everything in their corridor to keep it free
of dangerously large space dust. Again that laser highway. Even then, especially since those ships need
large sails for targeting with lasers, I wouldn’t ever aim for more than 86% of light speed. Same for antimatter, it just isn’t worth
going faster even if you can produce that substance for peanuts and store it safely. Frankly both are kind of silly speeds anyway,
you don’t engage in routine interstellar travel unless you have either biological immortality
or can freeze and thaw people, and as I’ve discussed before the latter ability almost
requires the former. In which case time doesn’t matter much,
everything still takes many years that your destination experiences and you either don’t
or don’t care about it because you’ve got as much time as you want. That’s our topic for next week, life extension,
something we looked at briefly last year but will look at in more detail. So on ship speeds, for fusion, depending on
how good it gets, anywhere from 5-30% of light speed, though the latter is really pushing
it unless you’ve got some material that can reflect neutrinos. Micro-Black holes can do better, especially
if you can feed them, ditto anti-matter and laser-sails, but realistically not much over
half to maybe 90% of light speed. As to shape, your typical interstellar ship
ought to look like an unsharpened pencil, and as we’ve discussed before the energy
needs just to get up to tiny fraction light speed so dwarf the energy needed to operate
life support and operations that even on a wasteful glutton’s budget over centuries
they would look like a rounding error compared to your fuel needs. Our lasers and massively over-powered mega
radar will add to that, but not too much. Yet while the main body of the ship might
look like a pencil it will probably have those frontal foil shields stretching over millions
of kilometers ahead and thin projections sticking off to the side like spokes on a wheel, another
reason why the outer hull of the ship either does not spin or does so very slowly, even
though you’d have big rotating habitat sections inside. 250 meter radius is probably as wide as you’d
ever build a ship since that is our estimate for the widest you’d need to maintain Earth-like
pseudo-gravity that people didn’t get motion sickness from. Hopefully by now you’ve got a pretty good
idea why these sorts of ships never have maximum speeds put on them or almost always get described
as very long and narrow. Totally different ball game from interplanetary
ships, though they’d also probably be long cylinders with a big forward shield telescoped
out ahead of it and spoke like projections for sensors and collision lasers. Just scaled down a lot. Spaceship designs are never going to look
very cool, or maybe we’d change our notion of cool, after all planes and sports cars
and motorcycles and rockets are not objectively that cool looking but we come to view them
that way for all the implied speed and power of the design. Okay, we will stop there for today. Next week we will look at life extension in
some more detail and look at how that might actually happen in our lifetimes, along with
the some of the implications of that on society. We’ve discussed it before in bits and pieces
but this time we’ll focus down more on the technology, the hurdles and challenges, and
the impact of it on civilization. Make sure to subscribe to the channel for
alerts when that and other episodes come out, and if you enjoyed this episode, please like
it and share it with others. Until next time, thanks for watching, and
have a great week!

100 thoughts on “Interstellar Travel Challenges”

  • Isaac, sorry for not going through the previous 962 comments, so I may be repeating something here, but why are we talking about metallic type shields and blasting micrometeorites with lasers? Your craft looks like it is of a technologically advanced stage where each floor has artificial gravity. Wouldn't we have developed an actual force field by that stage? I mean we already have the means of repelling like polarity objects with electromagnets, so why couldn't we project a very strong positively charged magnetic "shield" around the front 4/5 of the craft, with a closer negative charged field, and finally an electrical screen that then vaporizes anything that gets through the first 2 barriers? Then, because this thing was obviously built in space (so it's weight and mass aren't much of a factor), have the outer hull 3cm thick carbon fiber, a 4mm thick self-sealing rubber sealant on the inside, a 5ft gap (for various test/maintenance equipment, conduits, hull inspections/repairs, and maintained at a positive pressure) then an inner hull with the same composition so that if the outer hull happens to be breached to where the sealant can't completely seal the hole, there still won't be an explosive decompression. There could also be positioned between each bulkhead, a decompression activated canister that dispenses an expanding foam to completely seal off the affected area from the rest of the maintenance compartment. Maybe having alternating positive/negative fields will have the added benefit of protecting the inhabitants from some of the most harmful types of radiation (someone should test that theory). Since this is an enormous ship, it can have multiple nuclear reactors aft for propulsion and electrical generation (assuming we haven't perfected fusion drives by the time it is built), so we should be able to generate the power required.

  • Righto, because apparently everyone has the patience to wait thousands of years to meet another civilization. I don't care what civilization my great great great great great grandkids will get to see. Especially if I may not even be having kids. What I care is getting there fast enough for me to meet another civilization.

  • Your speech is fine. I'd call it an accent if anything. I was in speech-class for years due to a mutation involving my tongue. Do/did you have the same mutation?

  • Wolf NZ Outdoors says:

    A great video on the ISM. Years ago my mates and I were discussing space travel at relativistic speeds and I pointed out that space isn't truly empty and even a grain of sand hitting the ship at a decent percentage (>50%) would do serious damage and that the likelihood of that happening would be extremely high as, at >50% of c, they'd be carving through a fair bit of space each second.

    Absolutely brilliant episode. Great work, Isaac, keep it up.

  • We will have to build our own Earth planet spaceships accompanied by a custom built sun. Many of them, in all directions. Yes it will take a long time but hey, we can't go past light speed so we have to play the long game. It sometimes makes me wonder if we migrated to earth from somewhere else. Perhaps we have always been travelling through the Universe.

  • Derek Bertrand says:

    I know this guy is super smart but its too hard to listen to the content over that horribld speech impediment. Why can't he pronounce the letter R?

  • What about (say…) 10 meters thick cover of cotton layers on the spaceship's front? Perhaps with additional layers of some sort of carbon fiber crap.. Perhaps self-closing (self-repairing) material from minuscule damage..
    Would that negate the kinetic energy potential damage from the "space dust bullets" ?
    I mean.. ye sure.. fancy umbrellas flying in front of the spacecraft .. which would be increasingly harder to control the further away they are.. Why not just have a decent protection on 1st place, instead of going to the trouble of sending sh1t in front and creating more problems than solving?

  • We'll never travel interstellar space. Even at the speed of light travel, the universe is just to big. Worth noting that nothing with mass can reach the speed of light.

  • This is really interesting n all but I can't concentrate with the narrator sounding like a baby or something from the loney toons

  • I think blowing a nuke on the 100 tonne sail will destroy it and maybe send pieces flying everywhere, including into the main ship..

  • I want to add that you a fantastic human being. Whatever path that has led you here, the rest of us will join and follow you into your futuristic and imaginative venture.

  • Quite conservative on Your math on propulsion Sir Arthur.
    I'd commend this before, and I'd really love Your consideration on this subject:
    Conditioned, I'm able to project gravity.
    As projecting gravity in front of me (the direction I want to go), I am (on a local scale, I am NOT) breaking "LTF"!
    Relatively, I could go with ANY (relative) speed!
    The nutcase is essentially:
    We are not really sure IF "FTL" IS possible?
    However, I don't care, if I can project gravity!
    possible? – I don't know (but hope)!
    – But it seems obvious to me, that being "dragged", is more energy efficient than, for ex. creating a "wormhole" (simple logic proved somethingizh like front-wheel-drive). Creating a "wormhole", I'd had to equalize gravity*distance in energy. Being "dragged", I'd only have to maintain energy for my "drive" (drag).
    Dear Sir Arthur, how do you come down with this calculation?

  • Marcel Rodriguez says:

    All other challenges can be fixed except the one we cant…. and that is that we are just too fucking slow. Even reaching light speed is stupid slow.

  • If you know where you are going why not build a series of stel-lasers and have them pointed in the direction you are going a few years ahead of time to help clear the way, it won't get rid of rogue planets but it should clear the path of most minor debris and if set up right could give a early warning system on massive objects which would allow you to alter course.

  • Do we really think this is ever going to happen? We can't even take care of our own planet. Lets worry about ending war and poverty on Earth first.

  • a strange thought I had in regards to Generation/sleeper vessels where some people sleep for the whole Journey and others do not. When thinking about
    cultural drift, the people who were "sleeping" (dead) would not experience that drift at all. So the people they knew when they joined the crew
    and might have even been friends with some of, and certainly those who were born on the journey would be complete or almost complete strangers to them. I
    mean even with super life extension, and sporadic contact from earth. I am just thinking how different people I knew when I was in High School are when I meet
    them now, some 27 to 30 years later. it would be weird because when you woke up you would be a stranger among people who in your mind you know. Just a weird
    little thought that popped into my head with regards to cultural drift

  • Frank Shifreen says:

    Isaac- why can't a ship have a magnet- antimagnet that diverts dust and smaller objects from the ship- Of course not now but in the future?- instead of a beam that would destroy micro-objects via rays or lasers etc

  • Nice vid, but a bit rosy. I can think of several other challenges.

    1: People going mad from spending their entire lives crammed in a can. If you've ever seen a bear in a zoo you'll know what I mean.
    2: Oort clouds possibly/probably the norm around stars. Which we haven't mapped at all obviously, and which are largely invisible at long distances. Hit something big just once, die in outer space. Exacerbated by high speeds presumably. Both with regard to your reaction time and the size of the objects it might become rather important to avoid.
    3: Radiation exposure over time, adequate radiation shielding. We can't do this at all right now, at least not in any practical manner.
    4: Ignorance about the practical conditions in the IS medium. Radiation levels, frequency and distribution of "rogue" matter, anomalies etc.
    5: Time delay. Maybe the most significant challenge with all of this. Any communication back to earth, or anywhere else, takes years; decades. All information received is by definition old in space. Difficult for the human mind to process.
    6: Unknowns. A star thought to be placid may turn out to be erratic. One solid solar flare right in your grill when you arrive could disable the ship; even kill all aboard instantly.
    7: Designing a functional contained system for all this biomass over such a time scale is pretty unrealistic. I know it all sort of works in theory, but there are always problems, even with simple systems. Let alone something of this scope. Lots of things looked good on paper, like the Afghanistan invasion and central banking.

    In general I would say that the biggest problem with manned space travel, period, is that it only takes one part of your ship and system to fail, one accident or unforeseeable calamity and you're probably dead. If not instantly, later as the system failures have time to cascade. Perhaps this is the reason why no human has left near-Earth orbit since 1972. It's just an extremely risky business all told. Not sure if I'll ever become as optimistic as you are about the prospects of any of this ever becoming real.

  • Great info. I suggest only that you practice the pronunciation of your words. Try reading out loud to yourself and someone else to help you improve your pronunciation so that your words are crisp, clear, and pronounced correctly. Blessings

  • Woman living for a very long time–it could happen. Women able to have children that whole time–I have a whole lot more trouble believing. How about young women born during the trip (20-somethings perhaps, like the species is designed for) be the ones having the children.

  • Would it be possible to decelerate with a laser launched ahead of the space craft shining back at it? You wouldn't really care if an unmanned laser craft flew off into space or crashed and it'd save on deceleration fuel right?

  • spencer kenney says:

    the people are still aging at same normal rate. just people back at earth are ageing an a very increased rate relative to people on ship

  • Pascual Hernandez says:


  • Quentin Browne says:

    I think he should stay where he is because he has total control..on a tv network he will be just another talking least here he is unique and can do whatever he wants

  • Thought this video was about the future of space travel but no it’s about spaceships that are in films, what a waste of time!! It’s not real..!!

  • Mathew Jackson says:

    Nerdy question: RE: the side attached Kms long cord for the point defence lasers – bend too much and break under acceleration???

    or is it due to low but constant acceleration that keeps it from breaking off?

    Thanks in advance.

  • Richard Deese says:

    I've been wondering about the efficacy of having a system like the following: Either have a hydrogen scoop out front, coated with Teflon (or something like it), or, have an aerogel infused with (and/or surrounded by) a hot plasma & magnetic field – along with some kind of laser system to fire at anything large enough to be targetable. It's very interesting to consider what humans would think & feel, if raised on a long-voyage colony ship traveling between stars (or even between galaxies.) I enjoy how you incorporate these very human elements into the mix, so to speak. Politics (& religion, for that matter) would almost certainly play a part of a colony ship's mission statement (if you'll allow me the quaintness of that terminology!) Perhaps there would indeed be the need for a captain to make emergency decisions – for instance, any potentially life-threatening situation. Otherwise, meetings would be regularly held of various groups & subgroups (with, perhaps, some of the people being in multiple groupings), & votes could be taken on various issues. One is tempted to wonder if a colony ship's population might revert to a sort of council of elders, but that's a whole different set of questions. I suppose that on such a big, populous ship, people would tend toward subgroups – as they would in any city – dividing under political, religious, cultural, & ideological 'pressures.' Keeping things together would be a challenge, of course. I personally would be more than willing to live on a large enough ship; after all, it's as good a place to live one's life as any. And, as you note, people born & raised there wouldn't know any different, except from learning human history. Shades of Battlestar Galactica, for sure! The ability (& the public desire) to retro-fit newer technology – & even to enlarge the ship, or create new, extra ships – is quite interesting, too. While there's every reason to expect that people on the ship would be advancing their knowledge & technological capabilities, I doubt there would be much desire for "news from home." The ship would be it's own, unique society, separate from any on Earth (or on whichever planet built it!) Especially since it could take centuries or millennia to communicate in just one direction – much less both. I'm not sure I'd even want my shipmates making too much of that emotional connection; but that's just me. I think it better to know human history, but to think of ourselves as an independent, completely autonomous society. That simplifies the decision-making process. We choose for ourselves – with no "missions" from "home"! If anybody wishes to break off & have their own ship(s), going wherever they decide, then that should be fine, with no strings attached. Communication would rapidly become a moot point, anyway. It's fascinating to consider a society where some members might be fully human – perhaps with life-extension – while others might be uploaded to robotic bodies, & some might even live within computer systems onboard, experiencing virtual realities, & tying in to the mainframe only when they desire (or when deemed necessary or beneficial.) I think most people don't consider that spaceships don't experience drag like a boat or an airplane would, & that it could be basically any shape that does the job. I remember the Disney's (Touchstone Pictures', I should say) movie "The Black Hole." [I hear they're remaking it, too!] They won an award for the skeletal-looking design of the ship – precisely because it didn't look like a typical science-fiction starship. Cool. Anyway, good job! Very enjoyable AND thought-provoking! Thanks. I'm looking forward to catching up on the rest of your videos. Rikki Tikki.

  • James Meritt says:

    Things would be much easier if we lived significantly more than a century. We could make things run much cooler and save on fuel if we didn’t have to rush. If we lived a few hundred thousand years we could go to nearby stars at a reasonable speed. It is a biological problem, not necessarily an engineering one.

  • Julian Danzer says:

    I actually think except for truly large rocks a mechanical shield could still work pretty well
    a starship would be pretty heavy anyways and if you make it long and narrow enough you can get a lot of volume behind a very thick shield that still has an acceptable mass
    make that shield out of some hightech ceramic foam structure and it should hold off anything you're likely to encounter and you can still have relatively basic radar and maneuvering thrusters to avoid anything too big
    also instead of turning around to slow down you'd probably swivel your engines – or have several engines or several nozzles – depending on how your engine works and which is easier to do – and have radial engines angled at 5° or so – loosing soem efficiency but only a tiny bit due to the way trigonometry works – your efficiency is now reduced by a factor of cos5° so you lost about 0.3% efficiency – but you can now place engines at the back of the ship safely behind the shield but with their exhaust blasting past the shield by the side

  • Julian Danzer says:

    look up whipple shields, too – have several layers of 5 centimeter thick armor spaced out with a hundred meters between them, say 20 of them stretched over 2 kilometers – follow that by a 50 meter low density / foam shield with csic or kevlar/ceramics layers in it and you can armor 0.1 square kilometers with 200000 tons of material – not much compared to the mass of a long narrow ship you can shield behind it

  • is there anyway to harness the energy of the micro collisions of the space "junk" back into thrust or powering the ship in other means?

  • Tom Starwalker says:

    Photons have recently been crashed together and turned into an electron positron pair. Apparently the particles can be steered.

  • Chris Schembari says:

    What about the Alcubierre principle for a warp drive? Seems like one of those theoretical future technologies that Isaac might explore as something we may develop in the next few millennia, long before our descendants build enough O'Neill cylinders to complete a Dyson swarm.

    Dr. Alcubierre proved* 25 years ago that one should be able to warp a small pocket of space without violating General Relativity. A ship with an honest-to-God warp drive would operate by collapsing space in front of the ship and expanding space behind it, thus shoving the pocket of space-time containing the ship forward. The ship isn't technically flying through space at FTL, it's sitting motionless in the pocket while the pocket of space is hurtling forward relative to the rest of space-time. While no upper speed limit for space-warping is known as yet, if there is one, per Dr. A, it would have to be the equivalent of at least several hundred million times lightspeed. As I recall.

    * I know, I know, Dr. A only proved it on paper, and no one knows how to actually do it yet.

    Edit: I just saw that Isaac addressed Dr. A in his FTL video. I'll be watching it as soon as I can.

  • I’m A Robot says:

    Why must the captain be a female? Aren’t males capable of being captains? Why are females always being pushed ahead of males just to virtue signal?

  • Awesome Video!
    At 8:20, your Kinetic Energy formula K=1/2mv^2 may be better described as K=(1/2)mv^2? For a moment, I thought that the mv^2 was also in the denominator, but it’s not. (Of course we know KE is not inversely proportional to mv^2.)

  • Ambokile Martin says:

    As intelligent as Issac may be, he needs to stop narrating. It's extremely annoying. How hard is it to say R ?

  • Joshua Traffanstedt says:

    Hi, arthur. I'm thinking of taking on the enormous task of writing a science fiction novel. What would you say is the most likely (and more importantly, BELIEVABLE) way(s) of interstellar space travel in the future. Something where the people that aren't traveling don't age too fast? I know theres light speed, but in my opinion, that isnt very likely. Not anytime within the next thousand years or so. Say a novel set 450 years from now.. how do you see interstellar travel going? If you already have videos of this, would you direct me to them, please? Thanks so much. Your channel is a gold mine for aspiring and current novelists! Cheers!

  • Michael Medcoff Medcoff says:

    Why search for the smaller partials to vaporize just put up a laser vapor Sheila in front of the ship

  • ThothHeart Maat says:

    For the space particles, why not a cosmic cow pusher or a cone that diverts particles away attached to the front? Or the AI radar particle tracking and auto laser firing system works pretty good too I guess..

  • Wouldn’t you think by then we would have developed some kind of energy shields that surround the ships to protect from objects?
    Don’t you think it would be smarter to build these ships in space so we can save on rocket fuel by not having to launch massive space ships from earths gravity?
    Or do you think perhaps we could have learned to harness gravity to move massive objects effectively and efficiently without the need for rocket fuel to escape earths gravity?
    Don’t you think it’s possible we could have discovered or developed more effective and efficient fuel to the point where we don’t need rocket fuel tanks the size of skyscrapers to leave earth?

  • is there any physics truth to the small object at high velocity causing damages ? I assume at small scale things don't behave the same way. at 9:30
    A grain of sand causing the same effect as a ton of dynamite

  • 8:29 OMG! WHAT'S WRONG? I understood that! In other words. If you could run like the flash, through a raining tropical storm,you would probably drown. Do you know what that means?!?! I'm stuck on this tiny blue planet,with all of you annoying,dull, PEOPLE!😋

  • shaun humphreys says:

    Found your videos late but, I love them! Thank you so much for all the hard work and time you put into them, and for being visionary enough to foresee the future of humanity. Many of the most popular scientists , for example here in Britain professor brian cox, are so unvisionary and doubt humans will ever leave this solar system, which is absurd because if you imagine human technological progress in 1000 years time, based on the rate of progress in the last 1000 years, humans will be unimaginably advanced. It is even my vision given this rate of progress, that humans will become so advanced that they will be able to even reverse the heat death of the universe or survive it by creating a pocket closed universe, or by manipulating the Higgs field or something. I genuinely cannot see humans ever going extinct.

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