Particle damage from near lightspeed travel in outer space

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nimbus

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From an off topic tangent in another thread:
robnissen":gd9a72iy said:
Its kind of the worst of all worlds. The few atoms, molecules and dust in interstellar space are too few and far between to be useful for anything. While at the same time, those few atoms, molecules and dust would quickly destroy a space ship going at any significant % of c, like .1c because of the extreme energies they would have due to their high speed relative to the ship. So, not only can we not use them as resources for an interstellar journey, their very existence will make an interstellar journey in any reasonable time period virtually impossible.
aremisasling":gd9a72iy said:
robnissen,

I'll take issue with you on that one. I've never heard that raised as an issue by anyone from sci fi folks to engineers actually contemplating interstellar travel. Dust, maybe, but individual atoms are unlikely to be an issue. I've heard it suggested that we could travel fractions of the speed of light outside of the gravitational envelope of solar systems, accelerating once outside of our own and decelerating on approach to the destination. Sure there's dust out there, and frankly a whole lot of who-knows-what, but it appears to be few and far between.
http://www.newscientist.com/article/dn1 ... speed.html
[...]
For a crew to make the 50,000-light-year journey to the centre of the Milky Way within 10 years, they would have to travel at 99.999998 per cent the speed of light. At these speeds, hydrogen atoms would seem to reach a staggering 7 teraelectron volts – the same energy that protons will eventually reach in the Large Hadron Collider when it runs at full throttle. "For the crew, it would be like standing in front of the LHC beam," says Edelstein.
[...]
The fatal dose of radiation for a human is 6 sieverts. Edelstein's calculations show that the crew would receive a radiation dose of more than 10,000 sieverts within a second. Intense radiation would also weaken the structure of the spacecraft and damage its electronic instruments.
And Brian Wang of NextBigFuture offers some suggestions:
http://nextbigfuture.com/2010/02/non-ma ... unter.html
 
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Light_Quantum

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Wait wait wait. Clear this up for me.

It says "For a crew to make the 50,000-light-year journey to the centre of the Milky Way within 10 years, they would have to travel at 99.999998 per cent the speed of light."

A light year is the distance light travels in a year. So if the center of the Milky Way is 50,000 light years away, how can a crew make it there in under 10 years by going less than the speed of light?
 
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Light_Quantum

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Excellent. From here on Earth it would seem like ~50,000 years, but for those on board it would only seem like 10.

The wording was a little unclear. Guess it's a matter of perspective.
 
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nimbus

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A matter of perspective: physicists and other guys in lab coats will refer to that as "reference frames".
 
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aremisasling

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I have read that one before, now that you mention it. But what was originally mentioned was a 'meaningful percent of the speed of light'. No one's proposing at the moment that we go to the center of the galaxy. 10%c is plenty for travel to Alpha Centauri by some plans, which produces far far lower energies than at .000001% shy of the speed of light. Besides, at that close to the speed of light, the energy of stray hydrogen atoms is far from the only problem we'd face.
 
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Solifugae

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We can overcome problems of radiation either by eventually enhancing humans, or having created AI that is as good as a human being. Then we can forgo living space and have a mostly solid craft.

The methods explained in the NBF article would help a lot too.

Actually, if we enhance humans or use robots/AI, then maybe such speed would be less of an issue, because we would be increasing our effective lifespan in which interstellar voyages could take place.
 
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nimbus

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aremisasling":1orgh8li said:
10%c is plenty for travel to Alpha Centauri by some plans, which produces far far lower energies than at .000001% shy of the speed of light. Besides, at that close to the speed of light, the energy of stray hydrogen atoms is far from the only problem we'd face.
Yes:
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But that still limits us, humans as we are now biologically and financially etc, to the very nearest stars. The progress of both propulsion and medical/life support tech, in this more-than-local-interstellar perspective, are actually pretty well matched.
 
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Floridian

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I think, if humans are able to travel .99% the speed of light, the sheer technological requirement for this would mean that our technology was very advanced. Surely these humans would be able to find a way around inter-stellar dust/atoms.

I'm sure different ideas have been discussed, and these may seem foolish but just a few ideas might be.

Whatever energy source is generating enough energy to propel us at near the speed of light could project a beam or some sort of pulse directly in front of the craft. If we were traveling at .99% the speed of light, these pulses would be within close distance of us, the more we fired, as long we were traveling in a straight line, the more protection we would have.

If we could somehow solve the issue of head-on collisions, collisions from the side, either directly into the side or at an angle become a problem as well, but perhaps we could have a system to divert these particles around the ship.

In the future, we may have armor or materials that are self-healing, what about reactive plating that explodes outwards when it feels the impact? Could this work fast enough?

Our ships may even be bio-mechanical, meaning the ship could be an organism, if its vital info were written into DNA sequences, it could heal large parts of the ship, but we are worried only about small holes. If an atom were to simply pass through the ship, as long as it didn't hit the reactor or any crew, no harm done right?

Perhaps the safety approach might by a circle circular craft, what I mean is, a giant circle, with the front of the circle (a huge area) facing head on. If possible, absorb/destroy particles coming from the front and hitting head on, if not possible, just let them pass right through and focus the crew in the center in a specially armed area. This ship would also have artificial gravity. Also, the spin of the ship itself might deflect atoms hitting on the sides? A system of inter-locking circles rotating at extremely high speeds, with the center of the ship being where the crew and energy sources were located.

What about super-heating the area where the particle were to hit, or having a layer of liquid or something?


Aside from those ideas, if we can warp space-time, we can travel through space by moving the space around us, shrinking and expanding, and particles won't hit us at a high velocity as our actual speed won't be very high, correct?



Other ideas might be, de-orbiting a moon and using it as a space-ship, though we would need mass amounts of energy. What about propelled huge objects like moons or planets, what about a planet with a giant inner layer of armor and living space surrounded by oceans (difficult but possible to engineer), what would happen when an atom collided with the oceans? Would it explode? Or a space rock.

If Possible, have a layer of protective armor that counter-rotates against the rotation of the planet so that it always faces one direction, this layer of armor would absorb/protect, and if it were self-healing would heal after an impact, it would also contain the explosion and loss of water?

Basically, a giant engineered planet, with a solid inner core, or solid inner core around a molten inner core surrounded on all sides by giant oceans, and on the front side of the planet (the direction it was traveling), a counter-rotating armor plate. The armor plate would have parts that stretched around the entire planet, so that it could "rotate" but would only entirely cover the front part.
 
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robnissen

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Interstellar dust and particles is just a HUGE problem for traveling at any significent percentage of c. I do not know at what speed, hydrogen atoms become deadly, but any ship we had today would be virtually instantly destroyed at .1c by insterstellar dust. The only workable solution that anyone has proposed, is to have a massive shield made of ice in front of the ship and as it gets cracked from interstellar dust, to constantly remake the shiled by recirculating liquid water to refreeze the shield. The problem with this method, is that the shield would need to be huge, I do not recall the exact size, but it would greatly increase the mass that must be accelelerated to .1c, which makes obtaining .1c even more difficult.

BTW, the following suggestion violates relativity:

Floridian":3iph740o said:
Whatever energy source is generating enough energy to propel us at near the speed of light could project a beam or some sort of pulse directly in front of the craft. If we were traveling at .99% the speed of light, these pulses would be within close distance of us, the more we fired, as long we were traveling in a straight line, the more protection we would have.
The speed of light is always constant, regardless of the speed of the observer. Thus, if a space ship is going .99c and it shines a beam of light in the direction of motion, the speed of that beam of light is c relative to the ship. Conversely, if a beam of light was shined (shone?) in the opposite direction to the direction of motion of the space ship, the speed of that beam of light relative to the ship is still C. Although, very counter-intuitive, Einstein postulated, and it has been repeatedly proven, that the speed of light relative to any observer never changes, no matter what the speed of that observer is.
 
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