5 ms·

I wonder if this is a factor limiting interstellar travel. Where spaceships are not able to approach light speed because they will quickly accumulate a ton of s

I wonder if this is a factor limiting interstellar travel. Where spaceships are not able to approach light speed because they will quickly accumulate a ton of space grease.

alex_duf 8y ago
Or that grease can be captured processed and burnt to reach the speed faster, (though I'm reading elsewhere the density is so thin there's no point almost)
- imglorp 8y ago
  You'd need an oxidizer too. They're talking about napthalene, C10H8.
  - kijin 8y ago
    There's a lot of oxygen in space, too. Just like carbon, though, it will be bound to hydrogen.
  - marcosdumay 8y ago
    You'd need a fusion reactor capable of merging carbon atoms.
    - tim333 8y ago
      Just merge the hydrogens and accelerate the other stuff as ions out the back.
krapp 8y ago
I would suspect that accumulated space grease is an insignificant factor when compared to a ship's existing energy/mass ratio and the effects of relativity and time dilation, where energy requirements and an object's apparent mass tend towards infinity as it approaches lightspeed. It's probably no more a factor than how thick the paint is on the hull.
- anoncoward111 8y ago
  I think a collision at > 0.1x light speed with pretty much any molecule would cause a loss of the vehicle
  - jacobush 8y ago
    Not with a big graphite shield - single molecules should just ablate it. However should you hit be unfortunate enough to hit one of those dust specks which are out there... big kaboom. The whole thing is also a case for building spacecraft with as small a cross section as possible, less chance of hitting something large.
    - anoncoward111 8y ago
      Thank you!!! So basically a frisbee traveling at light speed :)
      - jacobush 8y ago
        I guess you think of flying saucers... :-) A long spear is an even better shape, though.
    - nerdponx 8y ago
      Either way, I think this makes for some cool world building and speculative fiction.
  - ben_w 8y ago
    A relative speed of 0.1c would make every fully ionised helium atom into an overly wordy description of 18.64 MeV alpha particle radiation. Low density regions of interstellar medium can have as few as 10e-4 particles per cubic centimetre. At 0.1c, that density works out as 3e10 particles/m^2/s. At that density and energy per particle, 0.0895 W/m^2. Low enough you wouldn’t care. Molecular clouds, on the other hand, can be up to 10e6 particles/cm^3. Most of those molecules are hydrogen, so they don’t hit as hard on average… but that’s a rounding error compared to the density, so let’s say about half a gigawatt per square meter. TL;DR — go around the molecular clouds until you invent a Trek-like navigational deflector.
kirykl 8y ago
Maybe it's a waste product from interstellar ships
tenaciousDaniel 8y ago
grease is slippery so what if it helps them move faster
- rytill 8y ago
  Spacetime is pretty slippery already. At least, I haven't been able to stop moving through it yet.
  - _jal 8y ago
    I think the secret is crankiness. I have a family member who is stuck in the 70s.
    - coldtea 8y ago
      To their defence, that's a way better decade to be stuck at compared to anything that came after...
      - smt88 8y ago
        That's true for a minority of living humans[1]. In the US, it's certainly not true for LGBTQ people, women, or racial minorities, all of whom have more rights now than we did in the 70s. https://www.theguardian.com/news/2017/jul/28/is-the-world-really-better-than-ever-the-new-optimists https://www.theguardian.com/news/2017/jul/28/is-the-world-re...
        coldtea 8y ago
        >That's true for a minority of living humans[1]. In the US, it's certainly not true for LGBTQ people, women, or racial minorities, all of whom have more rights now than we did in the 70s. It could just as well be true for all of them as well (assuming it is for the rest of course). The "but now X group has rights" argument doesn't mean much. Such rights are a small, and rather insignificant part of life. Women, gays, lesbians, and racial minorities had huge great movements and tons of fan in the 70s in their everyday life as well. It's not like their whole existence was diminished by how others conceived them or whether they had this or that law. A black who had a steady Detroit job in the 70s in a nice home, family and so on, felt much better off than an unemployed same-aged man in Detroit today, even if the second has more nominal rights and articles about him now (not to mention that there are probably more police shootings of blacks today than in the 70s, and let's not even compare Trump to Carter or even Nixon on that regard). Or go talk to gay people, and see how they feel about the 70s and 80s, and various scenes that existed then compared to today. You'd be surprised Living in a looser and laxer decade can be more important than having some right in some law book (gays then partied far more widely and extravagantly than the meagre contemporary scene where they have rights, sure, but society is run by prudes and money spoilt most scenes). Heck, in the same period we had a full blow military dictatorship in my country, and people can still wax poetically about the times and the fun they had. Even people persecuted then and even tortured by the police at this point or another.
Semirhage 8y ago
Any matter starts to resemble a nuclear detonation as you impact it approaching c. As your relative velocity becomes Relativistic in relation to the matter you’re impacting, the energy liberated increases in a non-linear scale. Grease, individual hydrogen atoms, anything. You’d really need some kind of exotic material, a few kilometers of ablative shielding, or “energy shielding” to make near-c velocities work. You’d be slowed down, but you’d also be blown to bits... tricky thing relativistic velocities.

I wonder if this is a factor limiting interstellar travel. Where spaceships are not able to approach light speed because they will quickly accumulate a ton of space grease.

alex_duf 8y ago

Or that grease can be captured processed and burnt to reach the speed faster, (though I'm reading elsewhere the density is so thin there's no point almost)

imglorp 8y ago
You'd need an oxidizer too. They're talking about napthalene, C10H8.
- kijin 8y ago
  There's a lot of oxygen in space, too. Just like carbon, though, it will be bound to hydrogen.
- marcosdumay 8y ago
  You'd need a fusion reactor capable of merging carbon atoms.
  - tim333 8y ago
    Just merge the hydrogens and accelerate the other stuff as ions out the back.

krapp 8y ago

I would suspect that accumulated space grease is an insignificant factor when compared to a ship's existing energy/mass ratio and the effects of relativity and time dilation, where energy requirements and an object's apparent mass tend towards infinity as it approaches lightspeed. It's probably no more a factor than how thick the paint is on the hull.

anoncoward111 8y ago
I think a collision at > 0.1x light speed with pretty much any molecule would cause a loss of the vehicle
- jacobush 8y ago
  Not with a big graphite shield - single molecules should just ablate it. However should you hit be unfortunate enough to hit one of those dust specks which are out there... big kaboom. The whole thing is also a case for building spacecraft with as small a cross section as possible, less chance of hitting something large.
  - anoncoward111 8y ago
    Thank you!!! So basically a frisbee traveling at light speed :)
    - jacobush 8y ago
      I guess you think of flying saucers... :-) A long spear is an even better shape, though.
  - nerdponx 8y ago
    Either way, I think this makes for some cool world building and speculative fiction.
- ben_w 8y ago
  A relative speed of 0.1c would make every fully ionised helium atom into an overly wordy description of 18.64 MeV alpha particle radiation. Low density regions of interstellar medium can have as few as 10e-4 particles per cubic centimetre. At 0.1c, that density works out as 3e10 particles/m^2/s. At that density and energy per particle, 0.0895 W/m^2. Low enough you wouldn’t care. Molecular clouds, on the other hand, can be up to 10e6 particles/cm^3. Most of those molecules are hydrogen, so they don’t hit as hard on average… but that’s a rounding error compared to the density, so let’s say about half a gigawatt per square meter. TL;DR — go around the molecular clouds until you invent a Trek-like navigational deflector.

kirykl 8y ago

Maybe it's a waste product from interstellar ships

tenaciousDaniel 8y ago

grease is slippery so what if it helps them move faster

rytill 8y ago
Spacetime is pretty slippery already. At least, I haven't been able to stop moving through it yet.
- _jal 8y ago
  I think the secret is crankiness. I have a family member who is stuck in the 70s.
  - coldtea 8y ago
    To their defence, that's a way better decade to be stuck at compared to anything that came after...
    - smt88 8y ago
      That's true for a minority of living humans[1]. In the US, it's certainly not true for LGBTQ people, women, or racial minorities, all of whom have more rights now than we did in the 70s. https://www.theguardian.com/news/2017/jul/28/is-the-world-really-better-than-ever-the-new-optimists https://www.theguardian.com/news/2017/jul/28/is-the-world-re...
      - coldtea 8y ago
        >That's true for a minority of living humans[1]. In the US, it's certainly not true for LGBTQ people, women, or racial minorities, all of whom have more rights now than we did in the 70s. It could just as well be true for all of them as well (assuming it is for the rest of course). The "but now X group has rights" argument doesn't mean much. Such rights are a small, and rather insignificant part of life. Women, gays, lesbians, and racial minorities had huge great movements and tons of fan in the 70s in their everyday life as well. It's not like their whole existence was diminished by how others conceived them or whether they had this or that law. A black who had a steady Detroit job in the 70s in a nice home, family and so on, felt much better off than an unemployed same-aged man in Detroit today, even if the second has more nominal rights and articles about him now (not to mention that there are probably more police shootings of blacks today than in the 70s, and let's not even compare Trump to Carter or even Nixon on that regard). Or go talk to gay people, and see how they feel about the 70s and 80s, and various scenes that existed then compared to today. You'd be surprised Living in a looser and laxer decade can be more important than having some right in some law book (gays then partied far more widely and extravagantly than the meagre contemporary scene where they have rights, sure, but society is run by prudes and money spoilt most scenes). Heck, in the same period we had a full blow military dictatorship in my country, and people can still wax poetically about the times and the fun they had. Even people persecuted then and even tortured by the police at this point or another.

Semirhage 8y ago

Any matter starts to resemble a nuclear detonation as you impact it approaching c. As your relative velocity becomes Relativistic in relation to the matter you’re impacting, the energy liberated increases in a non-linear scale. Grease, individual hydrogen atoms, anything. You’d really need some kind of exotic material, a few kilometers of ablative shielding, or “energy shielding” to make near-c velocities work. You’d be slowed down, but you’d also be blown to bits... tricky thing relativistic velocities.