5 ms·

Tangential question, but how is high speed space travel supposed to work with tiny space debris like this? You hear a lot about how a small constant acceleratio

Tangential question, but how is high speed space travel supposed to work with tiny space debris like this? You hear a lot about how a small constant acceleration can get you to effective speeds for galaxy hopping over time, but doesn't extreme velocity make tiny objects like this a massive threat? Like orders of magnitude larger than they are for current space vehicles? Is that a solveable problem?

mjburgess 4y ago
Well as big an issue is the energy required, ie., acceleration requires energy and your mass isnt constant as you increase velocity. So by the time you're anywhere near "galaxy hopping" you're requiring near infinite amounts of energy. Also note that there really isnt any "galaxy hopping" speed. The speed of light is incredibly slow compared to space distances. Even travelling at light, you're not getting many places in a human life time.
- brabel 4y ago
  You can actually cross the whole galaxy in a lifetime if you get really close to light speed, but measuring time from the perspective of your ship... for everyone on Earth, due to time dilation, it would take you hundreds of thousands of years though :(. Notice that if you could travel exactly at light speed, time would cease to exist and you could get anywhere in the universe instantly, as light itself experiences no time.
  - misja111 4y ago
    > Notice that if you could travel exactly at light speed, time would cease to exist and you could get anywhere in the universe instantly, as light itself experiences no time. This is not true. The easiest way to see why, is to realize that speed is relative: there is no difference in considering the observer to move with the speed of light towards the foton, or the foton to move with the speed of light towards the observer. Yet as you know, we observe light all the time and still we experience time.
    - tux3 4y ago
      Note that speed is relative, but time dilation is not. That's the twin paradox, they're both relatively moving away from each other, but only one 'ages slower'. Though I don't know what it means to say a photon doesn't experience time, and even more so for hypothetical humans travelling at the speed of light. That's outside the scope of what relativity predicts.
      - heavenlyblue 4y ago
        You could also say “only one ages faster” so this is not a paradox because of that.
      - misja111 4y ago
        Ok so let's say two humans pass each other by somewhere in the universe, each in their own spaceship, in opposite directions. They both travel with half the speed of light, so relative to each other with full light speed. Which one is the one aging slower?
        ubercore 4y ago
        They won't see each other moving at the speed of light though. This example is covered in any class on relativity. Having an approach velocity between two objects at the speed of light or greater is different than accelerating a frame of reference to c. When an approach velocity is c, nothing is actually _moving_ at c.
        Tyr42 4y ago
        In particular, it's acceleration you need to account for when talking about time dilation, not speed. And acceleration is less symmetric.
        ryandvm 4y ago
        Love the Fermilab series of videos. Here's the one that covers the Twin Paradox: https://www.youtube.com/watch?v=GgvajuvSpF4 https://www.youtube.com/watch?v=GgvajuvSpF4
    - 4y ago
- spywaregorilla 4y ago
  > Also note that there really isnt any "galaxy hopping" speed. The speed of light is incredibly slow compared to space distances. Even travelling at light, you're not getting many places in a human life time. Only from the perspective of an observer from earth though, no?
SturgeonsLaw 4y ago
Just wind the windows up
msandford 4y ago
It starts with something like this https://en.m.wikipedia.org/wiki/Whipple_shield https://en.m.wikipedia.org/wiki/Whipple_shield and probably moves on to superconducting magnetic shielding as well. It will have to be defense in depth. There could easily be some kind of liquid layer also so that it's capable of being renewed over time.
WJW 4y ago
Micrometeorite impacts are one of the many many many issues still outstanding for high speed space travel. Manned interstellar travel is one of those things that is more "centuries away" than "decades away", if humanity will manage to do it at all.
irrational 4y ago
A lot of science fiction about space travel brings up this issue. Sometimes it is hand waving about “shields”. The harder the sci-fi the more “realistic” the author will explain how the ship is shielded from impacts, but I don’t think I’ve ever read one that uses any technology we currently have.
- genpfault 4y ago
  > I don’t think I’ve ever read one that uses any technology we currently have. Is 'ice'[1] a technology? :) [1]: https://revelationspace.fandom.com/wiki/Lighthugger https://revelationspace.fandom.com/wiki/Lighthugger
mensetmanusman 4y ago
Giant laser beam fields that search the trajectory for any backscatter along with super sensitive superconducting single photon sensors to understand the precise debris field.
GuB-42 4y ago
At "galaxy hopping" velocities, i.e. relativistic, even light can be a problem. Even the emptiest of empty space still has photons moving around from the cosmic microwave background, and go fast enough, and these photons will turn into deadly ionizing radiation because of blueshift. And even before that, the term "object" starts to lose meaning when it comes to collisions, it becomes a bunch of elementary particles with enough energy to cause fusion reactions. It could be one of the xkcd "What If?" scenarios, Randall loves to imagine stuff moving at relativistic speeds, and usually, it doesn't end well...
salawat 4y ago
Yepper. This was actually the core of one of my questions that actually stumped a professor back in college. We were trying to write a simulation of a ship traveling through space. As usual, I got way too deep into it that I probably missed the entire point of building up fundamental simulation writing skills but stumbled onto much more fundamental problems/tradeoffs, like the tradeoff between detection/classification/reaction/dispatch/execution times and not ending up splattered across space by plowing into a semi-truck sized rock nobody saw in the space between stars at relativistic speeds. Because once you're at those soeeds relative to anything else, anything else is a huge problem by definition. Looking at our current technology, we can carve up time into multiples of billionths of seconds for 1 action on one datum, but that chain of decisions that leads to resolving the difference between first hand experience at high energy particle accelerator physics and safely avoiding said first hand experience requires time for: >Sensing equipment to generate an image/digital rendering of space ahead of you. Fundamental constraints exist on resolution and sensitivity here >Tranlation to a digital line format, and transmission to a system capable of consuming that representation and classifying threats >Propagating that list of threats to a system capable of quickly formulating a response (Second marshalling\transmission/unmarshalling cycle) >Getting that list of responses resolved to courses of action translated to instructions dispatched (marshalled/transmitted/unmarshalled), then dealing with the physical latency of the various effector systems All of this signal prop happening on a vessel yeeting itself along through space so quickly it can get to the next system (say Proxima Centauri) in say a decade, which means even with speed of light signal propagation, your vessel is going healthy fractions of a light-second per second, and you kinda needed this done yesterday. All of this clockwork potentially ruined by the possibility of an errant chunk of rock, sand or hydrogen just minding it's own business while a bunch of apes spend countless generations of focused effort to end up ruining it's day, and hopefully, surviving. The Apes, that is. The rock'll have a new story for the post Universal debrief. This was how science kinda ruined my life. Because even hydrogen hitting is ionizing at these speeds. Fleet Of Worlds plays with the idea a bit using handwavium inertialess drives to accelerate a gravitational rosette of worlds on the way out of the Galaxy, with their occupants terrified at the mere thought anyone may be charting their trajectory, and laying something in the way that could result in the sterilization of their species due to the relative speeds involved. Mind you, at that point, I was barely out of my first programming course. I don't even remember if I actually completed that assignment with a coded deliverable. I just remember several hours in deep discussion with my professor over how to model things like detection thresholds and things like that. Might have converged on "Just ignore it", but the more I think about it, the more I smile, because it really was a very good question that at the time I had no idea of how good it actually was.

mjburgess 4y ago

Well as big an issue is the energy required, ie., acceleration requires energy and your mass isnt constant as you increase velocity. So by the time you're anywhere near "galaxy hopping" you're requiring near infinite amounts of energy. Also note that there really isnt any "galaxy hopping" speed. The speed of light is incredibly slow compared to space distances. Even travelling at light, you're not getting many places in a human life time.

brabel 4y ago
You can actually cross the whole galaxy in a lifetime if you get really close to light speed, but measuring time from the perspective of your ship... for everyone on Earth, due to time dilation, it would take you hundreds of thousands of years though :(. Notice that if you could travel exactly at light speed, time would cease to exist and you could get anywhere in the universe instantly, as light itself experiences no time.
- misja111 4y ago
  > Notice that if you could travel exactly at light speed, time would cease to exist and you could get anywhere in the universe instantly, as light itself experiences no time. This is not true. The easiest way to see why, is to realize that speed is relative: there is no difference in considering the observer to move with the speed of light towards the foton, or the foton to move with the speed of light towards the observer. Yet as you know, we observe light all the time and still we experience time.
  - tux3 4y ago
    Note that speed is relative, but time dilation is not. That's the twin paradox, they're both relatively moving away from each other, but only one 'ages slower'. Though I don't know what it means to say a photon doesn't experience time, and even more so for hypothetical humans travelling at the speed of light. That's outside the scope of what relativity predicts.
    - heavenlyblue 4y ago
      You could also say “only one ages faster” so this is not a paradox because of that.
    - misja111 4y ago
      Ok so let's say two humans pass each other by somewhere in the universe, each in their own spaceship, in opposite directions. They both travel with half the speed of light, so relative to each other with full light speed. Which one is the one aging slower?
      - ubercore 4y ago
        They won't see each other moving at the speed of light though. This example is covered in any class on relativity. Having an approach velocity between two objects at the speed of light or greater is different than accelerating a frame of reference to c. When an approach velocity is c, nothing is actually _moving_ at c.
      - Tyr42 4y ago
        In particular, it's acceleration you need to account for when talking about time dilation, not speed. And acceleration is less symmetric.
      - ryandvm 4y ago
        Love the Fermilab series of videos. Here's the one that covers the Twin Paradox: https://www.youtube.com/watch?v=GgvajuvSpF4 https://www.youtube.com/watch?v=GgvajuvSpF4
  - 4y ago
spywaregorilla 4y ago
> Also note that there really isnt any "galaxy hopping" speed. The speed of light is incredibly slow compared to space distances. Even travelling at light, you're not getting many places in a human life time. Only from the perspective of an observer from earth though, no?

SturgeonsLaw 4y ago

Just wind the windows up

msandford 4y ago

It starts with something like this https://en.m.wikipedia.org/wiki/Whipple_shield https://en.m.wikipedia.org/wiki/Whipple_shield and probably moves on to superconducting magnetic shielding as well. It will have to be defense in depth. There could easily be some kind of liquid layer also so that it's capable of being renewed over time.

WJW 4y ago

Micrometeorite impacts are one of the many many many issues still outstanding for high speed space travel. Manned interstellar travel is one of those things that is more "centuries away" than "decades away", if humanity will manage to do it at all.

irrational 4y ago

A lot of science fiction about space travel brings up this issue. Sometimes it is hand waving about “shields”. The harder the sci-fi the more “realistic” the author will explain how the ship is shielded from impacts, but I don’t think I’ve ever read one that uses any technology we currently have.

genpfault 4y ago
> I don’t think I’ve ever read one that uses any technology we currently have. Is 'ice'[1] a technology? :) [1]: https://revelationspace.fandom.com/wiki/Lighthugger https://revelationspace.fandom.com/wiki/Lighthugger

mensetmanusman 4y ago

Giant laser beam fields that search the trajectory for any backscatter along with super sensitive superconducting single photon sensors to understand the precise debris field.

GuB-42 4y ago

At "galaxy hopping" velocities, i.e. relativistic, even light can be a problem. Even the emptiest of empty space still has photons moving around from the cosmic microwave background, and go fast enough, and these photons will turn into deadly ionizing radiation because of blueshift. And even before that, the term "object" starts to lose meaning when it comes to collisions, it becomes a bunch of elementary particles with enough energy to cause fusion reactions. It could be one of the xkcd "What If?" scenarios, Randall loves to imagine stuff moving at relativistic speeds, and usually, it doesn't end well...

salawat 4y ago

Yepper. This was actually the core of one of my questions that actually stumped a professor back in college. We were trying to write a simulation of a ship traveling through space. As usual, I got way too deep into it that I probably missed the entire point of building up fundamental simulation writing skills but stumbled onto much more fundamental problems/tradeoffs, like the tradeoff between detection/classification/reaction/dispatch/execution times and not ending up splattered across space by plowing into a semi-truck sized rock nobody saw in the space between stars at relativistic speeds. Because once you're at those soeeds relative to anything else, anything else is a huge problem by definition. Looking at our current technology, we can carve up time into multiples of billionths of seconds for 1 action on one datum, but that chain of decisions that leads to resolving the difference between first hand experience at high energy particle accelerator physics and safely avoiding said first hand experience requires time for: >Sensing equipment to generate an image/digital rendering of space ahead of you. Fundamental constraints exist on resolution and sensitivity here >Tranlation to a digital line format, and transmission to a system capable of consuming that representation and classifying threats >Propagating that list of threats to a system capable of quickly formulating a response (Second marshalling\transmission/unmarshalling cycle) >Getting that list of responses resolved to courses of action translated to instructions dispatched (marshalled/transmitted/unmarshalled), then dealing with the physical latency of the various effector systems All of this signal prop happening on a vessel yeeting itself along through space so quickly it can get to the next system (say Proxima Centauri) in say a decade, which means even with speed of light signal propagation, your vessel is going healthy fractions of a light-second per second, and you kinda needed this done yesterday. All of this clockwork potentially ruined by the possibility of an errant chunk of rock, sand or hydrogen just minding it's own business while a bunch of apes spend countless generations of focused effort to end up ruining it's day, and hopefully, surviving. The Apes, that is. The rock'll have a new story for the post Universal debrief. This was how science kinda ruined my life. Because even hydrogen hitting is ionizing at these speeds. Fleet Of Worlds plays with the idea a bit using handwavium inertialess drives to accelerate a gravitational rosette of worlds on the way out of the Galaxy, with their occupants terrified at the mere thought anyone may be charting their trajectory, and laying something in the way that could result in the sterilization of their species due to the relative speeds involved. Mind you, at that point, I was barely out of my first programming course. I don't even remember if I actually completed that assignment with a coded deliverable. I just remember several hours in deep discussion with my professor over how to model things like detection thresholds and things like that. Might have converged on "Just ignore it", but the more I think about it, the more I smile, because it really was a very good question that at the time I had no idea of how good it actually was.