Why haven't we yet tried accelerating a space station with people inside to a near light speed? [closed]Why is there a controversy on whether mass increases with speed?What Problems for 50 year space probe to Alpha Centauri?Quantum Mechanical Effects of an object accelerating near speed of light $c$?Do photons see shorter distances due to space contraction?Relativistic space travel?Break speed of light with infinite massHow much time passed for the passenger traveling with at speed-of-light spaceship?Time in spaceships near the speed of lightSpeed of light when acceleratingWhat would happen if something *rotated* with a tangential velocity near speed of light?Why do people float inside space station in space?
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Why haven't we yet tried accelerating a space station with people inside to a near light speed? [closed]
Why is there a controversy on whether mass increases with speed?What Problems for 50 year space probe to Alpha Centauri?Quantum Mechanical Effects of an object accelerating near speed of light $c$?Do photons see shorter distances due to space contraction?Relativistic space travel?Break speed of light with infinite massHow much time passed for the passenger traveling with at speed-of-light spaceship?Time in spaceships near the speed of lightSpeed of light when acceleratingWhat would happen if something *rotated* with a tangential velocity near speed of light?Why do people float inside space station in space?
$begingroup$
Is that something we could do if we use ion or nuclear thrusters?
Wouldn't people in the station reach 0.99993 speed of light in just 5 years accelerating at 1g and effectively travel into the future by 83.7 years?
That would be a great experiment and a very effective way to show relativity theory in action. I mean, the people inside the station would have effectively traveled into the future, how cool is that? Why haven't it been done yet?
special-relativity reference-frames acceleration estimation rocket-science
edited May 23 at 3:06
Qmechanic♦
110k122081283
asked May 22 at 11:52
Un1Un1
21437
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closed as off-topic by Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero May 23 at 14:47
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question appears to be about engineering, which is the application of scientific knowledge to construct a solution to solve a specific problem. As such, it is off topic for this site, which deals with the science, whether theoretical or experimental, of how the natural world works. For more information, see this meta post." – Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero
add a comment |
$begingroup$
Is that something we could do if we use ion or nuclear thrusters?
Wouldn't people in the station reach 0.99993 speed of light in just 5 years accelerating at 1g and effectively travel into the future by 83.7 years?
That would be a great experiment and a very effective way to show relativity theory in action. I mean, the people inside the station would have effectively traveled into the future, how cool is that? Why haven't it been done yet?
special-relativity reference-frames acceleration estimation rocket-science
edited May 23 at 3:06
Qmechanic♦
110k122081283
asked May 22 at 11:52
Un1Un1
21437
$endgroup$
closed as off-topic by Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero May 23 at 14:47
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question appears to be about engineering, which is the application of scientific knowledge to construct a solution to solve a specific problem. As such, it is off topic for this site, which deals with the science, whether theoretical or experimental, of how the natural world works. For more information, see this meta post." – Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero
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Comments are not for extended discussion; this conversation has been moved to chat.
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– Chris♦
May 22 at 19:12
3
$begingroup$
How is this different from the many other ways that show relativity in action, such as gravitational lensing? Besides, I expect to be travelling into the future later this evening, as do many others, so why is that special?
$endgroup$
– Don Branson
May 23 at 2:26
1
$begingroup$
@DanBranson: get me a beer while you're there? Thanks. :-)
$endgroup$
– Bob Jarvis
May 23 at 4:00
add a comment |
$begingroup$
Is that something we could do if we use ion or nuclear thrusters?
Wouldn't people in the station reach 0.99993 speed of light in just 5 years accelerating at 1g and effectively travel into the future by 83.7 years?
That would be a great experiment and a very effective way to show relativity theory in action. I mean, the people inside the station would have effectively traveled into the future, how cool is that? Why haven't it been done yet?
special-relativity reference-frames acceleration estimation rocket-science
edited May 23 at 3:06
Qmechanic♦
110k122081283
asked May 22 at 11:52
Un1Un1
21437
$endgroup$
Is that something we could do if we use ion or nuclear thrusters?
Wouldn't people in the station reach 0.99993 speed of light in just 5 years accelerating at 1g and effectively travel into the future by 83.7 years?
That would be a great experiment and a very effective way to show relativity theory in action. I mean, the people inside the station would have effectively traveled into the future, how cool is that? Why haven't it been done yet?
special-relativity reference-frames acceleration estimation rocket-science
special-relativity reference-frames acceleration estimation rocket-science
edited May 23 at 3:06
Qmechanic♦
110k122081283
asked May 22 at 11:52
Un1Un1
21437
edited May 23 at 3:06
Qmechanic♦
110k122081283
asked May 22 at 11:52
Un1Un1
21437
edited May 23 at 3:06
Qmechanic♦
110k122081283
edited May 23 at 3:06
Qmechanic♦
110k122081283
edited May 23 at 3:06
Qmechanic♦
110k122081283
110k122081283
asked May 22 at 11:52
Un1Un1
21437
asked May 22 at 11:52
Un1Un1
21437
asked May 22 at 11:52
Un1Un1
21437
21437
closed as off-topic by Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero May 23 at 14:47
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question appears to be about engineering, which is the application of scientific knowledge to construct a solution to solve a specific problem. As such, it is off topic for this site, which deals with the science, whether theoretical or experimental, of how the natural world works. For more information, see this meta post." – Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero
closed as off-topic by Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero May 23 at 14:47
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question appears to be about engineering, which is the application of scientific knowledge to construct a solution to solve a specific problem. As such, it is off topic for this site, which deals with the science, whether theoretical or experimental, of how the natural world works. For more information, see this meta post." – Kyle Kanos, WillO, John Rennie, Jon Custer, ZeroTheHero
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– Chris♦
May 22 at 19:12
3
$begingroup$
How is this different from the many other ways that show relativity in action, such as gravitational lensing? Besides, I expect to be travelling into the future later this evening, as do many others, so why is that special?
$endgroup$
– Don Branson
May 23 at 2:26
1
$begingroup$
@DanBranson: get me a beer while you're there? Thanks. :-)
$endgroup$
– Bob Jarvis
May 23 at 4:00
add a comment |
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– Chris♦
May 22 at 19:12
3
$begingroup$
How is this different from the many other ways that show relativity in action, such as gravitational lensing? Besides, I expect to be travelling into the future later this evening, as do many others, so why is that special?
$endgroup$
– Don Branson
May 23 at 2:26
1
$begingroup$
@DanBranson: get me a beer while you're there? Thanks. :-)
$endgroup$
– Bob Jarvis
May 23 at 4:00
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– Chris♦
May 22 at 19:12
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– Chris♦
May 22 at 19:12
3
3
$begingroup$
How is this different from the many other ways that show relativity in action, such as gravitational lensing? Besides, I expect to be travelling into the future later this evening, as do many others, so why is that special?
$endgroup$
– Don Branson
May 23 at 2:26
$begingroup$
How is this different from the many other ways that show relativity in action, such as gravitational lensing? Besides, I expect to be travelling into the future later this evening, as do many others, so why is that special?
$endgroup$
– Don Branson
May 23 at 2:26
1
1
$begingroup$
@DanBranson: get me a beer while you're there? Thanks. :-)
$endgroup$
– Bob Jarvis
May 23 at 4:00
$begingroup$
@DanBranson: get me a beer while you're there? Thanks. :-)
$endgroup$
– Bob Jarvis
May 23 at 4:00
add a comment |
5 Answers
5
active
oldest
votes
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It is not feasible because it would cost an enormous amount of energy
to accelerate the spacecraft.
To prove this let's calculate with some concrete numbers.
Very optimistically estimated, your spacecraft may have a mass of $m=1000text kg$ (enough for a few people and a small space capsule around them, but neglecting the mass of the fuel needed).
And you said you want a speed of $v=0.99993cdot c$.
Now you can calculate the relativistic kinetic energy of it:
$$beginalign
E_text k &= fracmc^2sqrt1-v^2/c^2 - mc^2 \
&= left(frac1sqrt1-v^2/c^2-1right) mc^2 \
&= left(frac1sqrt1-0.99993^2-1right)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= (84.5-1)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= 7.5 cdot 10^21text J
endalign$$
Now this is an enormous amount of energy.
It is comparable to the yearly total world energy supply.
(According to Wikipedia:World energy consumption
the total primary energy supply for the year 2013 was $5.67 cdot 10^20text J$.)
edited May 23 at 13:59
psmears
27316
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
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Comments are not for extended discussion; this conversation has been moved to chat.
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– tpg2114♦
May 23 at 14:45
add a comment |
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I'm no physicist, but, just to add to the list of insurmountable problems with this idea, I've always thought the hardest problem was the "air resistance" in space.
The density of interstellar space is about 1 atom per cubic centimeter. If your spaceship is 1 meter cubed, and travels at c for 1 second, you have travelled 300,000 kilometers, encountering 300 trillion atoms.
When you are moving at relativistic speeds, each proton you run into is delivering 0.003 joules of energy into you. For the above distance, that's 900 GJ. 100 seconds in, and you have experienced pushback equivalent to a nuclear bomb.
Things are a little bit better in the intergalactic medium, where the density is 1 atom per cubic meter, a million times less than in regular interstellar space. That means 900 MJ per second of travel. That's 1 ton of TNT every 5 seconds. Whew, much better!
I'm not even taking into account the possibility that fusion will be undergone for many of these atoms on the surface of your spaceship. Good luck finding a material that can withstand that.
I'm super amateur so I may be miscalculating here, please correct me if I am!
answered May 23 at 0:51
NachtNacht
32117
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At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
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– Nelson
May 23 at 3:07
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Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
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– Nacht
May 23 at 3:19
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Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
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– Luaan
May 23 at 7:29
3
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Obligatory xkcd regarding the possibility of fusion.
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– TypeIA
May 23 at 9:56
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@TypeIA yes, that xkcd heavily inspired this answer
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– Nacht
May 23 at 13:20
add a comment |
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In addition to the other conceptual aspects, there are practical ones.
If you accelerate at 1g for 5 years, then you'll end up x light years away, where x is going to be tedious to compute (I assume you integrate tanh((9.81 m/s^2)*(5 years)/c)), but is clearly going to be measured in *light-years*.
So you're clearly enitrely isolated from the earth, and in the middle of space.
You can't actually do anything interesting with the fact that you're "in the future", because out in space nothing's really happened. In order for it to be at all interesting you'd have to come back to Earth.
But you're also travelling at 0.999934479 c. Away from Earth
Now you have to turn around, and decelerate for 5 years to stop, and then spend another 10 years coming back.
So this 5 year trip, has turned into a 20 year trip, during which your space station has to be entirely self-sufficient ... and not have any problems.
We just don't have the systems to support an environment like that for that long.
Then you've got the psychological and sociological issues to take into account.
Plus the fact that you can't steer this thing.
I can imagine all of these problems being soluble, if we can create a high-10s of personnel space station.
But a) we haven't currently achieved that and I don't think we're anywhere plausibly near achieving that, and b) suddenly the numbers in Thomas Fritsch's answer aren't starting from 1,000kg, they're starting 1,000 tonnes or more!
answered May 23 at 5:57
BrondahlBrondahl
21317
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There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
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– Luaan
May 23 at 7:32
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@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
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– Brondahl
May 23 at 7:33
4
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And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
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– Brondahl
May 23 at 7:33
2
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@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
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– Chronocidal
May 23 at 12:00
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Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
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– Luaan
May 24 at 6:19
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Mission time.
One of the issues of a manned Mars missions is the time window for an optimal transfer. I takes about six months to get to Mars. If you want to leave for the Earth again using the same window, you have about 10 days to visit Mars.
That's the equivalent of flying from London to New York, visiting the tourist shop for 30 minutes, and then flying back.
But the next window is about 1.5 years later. If you take this window, including travel time to and from, that the mission will take about 2.5 years in isolation and close quarters.
We have no accurate data on the effect of being isolated and contained for such a period, and it is not as easy as you think. There is no way of reaching them or providing supplies. They need to be self-contained and handle all obstacles (e.g. mechanical failures) themselves.
Your proposed experiment would take twice as long. What you've also not accounted for is that the craft needs to slow down again, which would take another 5 years, making the whole mission four times longer than a Mars mission, which is already stretching the boundaries of what we are able to reliably achieve.
It's even worse than a Mars mission, because a Mars mission at least has radio contact. But as the crew gets exposed to time dilation (which will be noticeable much before they reach light speed) communication will become less feasible, and they will be truly alone.
Distance.
Travelling at high velocity (it doesn't even need to be near lightspeed) means that this craft cannot orbit the Earth anymore. So where will it travel? Well, you'd expect them to be about 2.5 lightyears removed from us (on average, they travelled at half of lightspeed during their 5 year speed up = 2.5 lightyears).
But don't forget to account for the slowdown. That's another 2.5 lightyears before they come to a "standstill" (if there were such a thing).
To put it into perspective, that's about 120% the distance to Alpha Centauri.
What's the point?
Okay, so let's say we accomplish all that and send the mission. Then what? They are in the future, out past Alpha Centauri, with no hopes of coming back and dwindling supplies. We can't find out what they experienced. We can't find out anything. There is no benefit to us whatsoever.
This is pretty much the equivalent of shooting a single person in a spacesuit in a particular direction with no comms or any way to get back. You're just sending someone out to a lonely death. You're not accomplishing anything.
And given the amount of time they will have traversed (keep in mind that time dilation will happen relative to their speed, so they will already experience more than half the time dilation for the last 2.5 years of their speed up time), it's likely that the humans alive then will have found other and better way to confirm relativistic effects.
So either the astronauts sacrificed themselves without contributing to the civilization that sent them; or they get picked up by a civilization that has already figured out the thing they gave their lives in pursuit of finding out. Neither is a good outcome.
answered May 23 at 8:40
FlaterFlater
1114
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I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
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– Brondahl
May 23 at 13:35
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@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
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– Flater
May 23 at 13:38
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The only current propulsion systems, that I know of, that could achieve high speeds is the same one they've been talking about for decades, setting off nuclear bombs behind a pusher plate. However, I heard somewhere that this would only be feasible for about 10% of the speed of light. And, like in the other answers, you would have to have protection from incoming atoms in space.
answered May 23 at 14:24
James MontagneJames Montagne
15
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5 Answers
5
active
oldest
votes
5 Answers
5
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
It is not feasible because it would cost an enormous amount of energy
to accelerate the spacecraft.
To prove this let's calculate with some concrete numbers.
Very optimistically estimated, your spacecraft may have a mass of $m=1000text kg$ (enough for a few people and a small space capsule around them, but neglecting the mass of the fuel needed).
And you said you want a speed of $v=0.99993cdot c$.
Now you can calculate the relativistic kinetic energy of it:
$$beginalign
E_text k &= fracmc^2sqrt1-v^2/c^2 - mc^2 \
&= left(frac1sqrt1-v^2/c^2-1right) mc^2 \
&= left(frac1sqrt1-0.99993^2-1right)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= (84.5-1)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= 7.5 cdot 10^21text J
endalign$$
Now this is an enormous amount of energy.
It is comparable to the yearly total world energy supply.
(According to Wikipedia:World energy consumption
the total primary energy supply for the year 2013 was $5.67 cdot 10^20text J$.)
edited May 23 at 13:59
psmears
27316
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
$endgroup$
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– tpg2114♦
May 23 at 14:45
add a comment |
$begingroup$
It is not feasible because it would cost an enormous amount of energy
to accelerate the spacecraft.
To prove this let's calculate with some concrete numbers.
Very optimistically estimated, your spacecraft may have a mass of $m=1000text kg$ (enough for a few people and a small space capsule around them, but neglecting the mass of the fuel needed).
And you said you want a speed of $v=0.99993cdot c$.
Now you can calculate the relativistic kinetic energy of it:
$$beginalign
E_text k &= fracmc^2sqrt1-v^2/c^2 - mc^2 \
&= left(frac1sqrt1-v^2/c^2-1right) mc^2 \
&= left(frac1sqrt1-0.99993^2-1right)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= (84.5-1)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= 7.5 cdot 10^21text J
endalign$$
Now this is an enormous amount of energy.
It is comparable to the yearly total world energy supply.
(According to Wikipedia:World energy consumption
the total primary energy supply for the year 2013 was $5.67 cdot 10^20text J$.)
edited May 23 at 13:59
psmears
27316
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
$endgroup$
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– tpg2114♦
May 23 at 14:45
add a comment |
$begingroup$
It is not feasible because it would cost an enormous amount of energy
to accelerate the spacecraft.
To prove this let's calculate with some concrete numbers.
Very optimistically estimated, your spacecraft may have a mass of $m=1000text kg$ (enough for a few people and a small space capsule around them, but neglecting the mass of the fuel needed).
And you said you want a speed of $v=0.99993cdot c$.
Now you can calculate the relativistic kinetic energy of it:
$$beginalign
E_text k &= fracmc^2sqrt1-v^2/c^2 - mc^2 \
&= left(frac1sqrt1-v^2/c^2-1right) mc^2 \
&= left(frac1sqrt1-0.99993^2-1right)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= (84.5-1)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= 7.5 cdot 10^21text J
endalign$$
Now this is an enormous amount of energy.
It is comparable to the yearly total world energy supply.
(According to Wikipedia:World energy consumption
the total primary energy supply for the year 2013 was $5.67 cdot 10^20text J$.)
edited May 23 at 13:59
psmears
27316
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
$endgroup$
It is not feasible because it would cost an enormous amount of energy
to accelerate the spacecraft.
To prove this let's calculate with some concrete numbers.
Very optimistically estimated, your spacecraft may have a mass of $m=1000text kg$ (enough for a few people and a small space capsule around them, but neglecting the mass of the fuel needed).
And you said you want a speed of $v=0.99993cdot c$.
Now you can calculate the relativistic kinetic energy of it:
$$beginalign
E_text k &= fracmc^2sqrt1-v^2/c^2 - mc^2 \
&= left(frac1sqrt1-v^2/c^2-1right) mc^2 \
&= left(frac1sqrt1-0.99993^2-1right)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= (84.5-1)cdot 1000 text kgcdot (3cdot 10^8text m/s)^2 \
&= 7.5 cdot 10^21text J
endalign$$
Now this is an enormous amount of energy.
It is comparable to the yearly total world energy supply.
(According to Wikipedia:World energy consumption
the total primary energy supply for the year 2013 was $5.67 cdot 10^20text J$.)
edited May 23 at 13:59
psmears
27316
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
edited May 23 at 13:59
psmears
27316
edited May 23 at 13:59
psmears
27316
edited May 23 at 13:59
psmears
27316
27316
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
answered May 22 at 12:33
Thomas FritschThomas Fritsch
3,05911323
3,05911323
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
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– tpg2114♦
May 23 at 14:45
add a comment |
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
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– tpg2114♦
May 23 at 14:45
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– tpg2114♦
May 23 at 14:45
$begingroup$
Comments are not for extended discussion; this conversation has been moved to chat.
$endgroup$
– tpg2114♦
May 23 at 14:45
add a comment |
$begingroup$
I'm no physicist, but, just to add to the list of insurmountable problems with this idea, I've always thought the hardest problem was the "air resistance" in space.
The density of interstellar space is about 1 atom per cubic centimeter. If your spaceship is 1 meter cubed, and travels at c for 1 second, you have travelled 300,000 kilometers, encountering 300 trillion atoms.
When you are moving at relativistic speeds, each proton you run into is delivering 0.003 joules of energy into you. For the above distance, that's 900 GJ. 100 seconds in, and you have experienced pushback equivalent to a nuclear bomb.
Things are a little bit better in the intergalactic medium, where the density is 1 atom per cubic meter, a million times less than in regular interstellar space. That means 900 MJ per second of travel. That's 1 ton of TNT every 5 seconds. Whew, much better!
I'm not even taking into account the possibility that fusion will be undergone for many of these atoms on the surface of your spaceship. Good luck finding a material that can withstand that.
I'm super amateur so I may be miscalculating here, please correct me if I am!
answered May 23 at 0:51
NachtNacht
32117
$endgroup$
$begingroup$
At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
$endgroup$
– Nelson
May 23 at 3:07
$begingroup$
Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
$endgroup$
– Nacht
May 23 at 3:19
$begingroup$
Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
$endgroup$
– Luaan
May 23 at 7:29
3
$begingroup$
Obligatory xkcd regarding the possibility of fusion.
$endgroup$
– TypeIA
May 23 at 9:56
$begingroup$
@TypeIA yes, that xkcd heavily inspired this answer
$endgroup$
– Nacht
May 23 at 13:20
add a comment |
$begingroup$
I'm no physicist, but, just to add to the list of insurmountable problems with this idea, I've always thought the hardest problem was the "air resistance" in space.
The density of interstellar space is about 1 atom per cubic centimeter. If your spaceship is 1 meter cubed, and travels at c for 1 second, you have travelled 300,000 kilometers, encountering 300 trillion atoms.
When you are moving at relativistic speeds, each proton you run into is delivering 0.003 joules of energy into you. For the above distance, that's 900 GJ. 100 seconds in, and you have experienced pushback equivalent to a nuclear bomb.
Things are a little bit better in the intergalactic medium, where the density is 1 atom per cubic meter, a million times less than in regular interstellar space. That means 900 MJ per second of travel. That's 1 ton of TNT every 5 seconds. Whew, much better!
I'm not even taking into account the possibility that fusion will be undergone for many of these atoms on the surface of your spaceship. Good luck finding a material that can withstand that.
I'm super amateur so I may be miscalculating here, please correct me if I am!
answered May 23 at 0:51
NachtNacht
32117
$endgroup$
$begingroup$
At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
$endgroup$
– Nelson
May 23 at 3:07
$begingroup$
Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
$endgroup$
– Nacht
May 23 at 3:19
$begingroup$
Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
$endgroup$
– Luaan
May 23 at 7:29
3
$begingroup$
Obligatory xkcd regarding the possibility of fusion.
$endgroup$
– TypeIA
May 23 at 9:56
$begingroup$
@TypeIA yes, that xkcd heavily inspired this answer
$endgroup$
– Nacht
May 23 at 13:20
add a comment |
$begingroup$
I'm no physicist, but, just to add to the list of insurmountable problems with this idea, I've always thought the hardest problem was the "air resistance" in space.
The density of interstellar space is about 1 atom per cubic centimeter. If your spaceship is 1 meter cubed, and travels at c for 1 second, you have travelled 300,000 kilometers, encountering 300 trillion atoms.
When you are moving at relativistic speeds, each proton you run into is delivering 0.003 joules of energy into you. For the above distance, that's 900 GJ. 100 seconds in, and you have experienced pushback equivalent to a nuclear bomb.
Things are a little bit better in the intergalactic medium, where the density is 1 atom per cubic meter, a million times less than in regular interstellar space. That means 900 MJ per second of travel. That's 1 ton of TNT every 5 seconds. Whew, much better!
I'm not even taking into account the possibility that fusion will be undergone for many of these atoms on the surface of your spaceship. Good luck finding a material that can withstand that.
I'm super amateur so I may be miscalculating here, please correct me if I am!
answered May 23 at 0:51
NachtNacht
32117
$endgroup$
I'm no physicist, but, just to add to the list of insurmountable problems with this idea, I've always thought the hardest problem was the "air resistance" in space.
The density of interstellar space is about 1 atom per cubic centimeter. If your spaceship is 1 meter cubed, and travels at c for 1 second, you have travelled 300,000 kilometers, encountering 300 trillion atoms.
When you are moving at relativistic speeds, each proton you run into is delivering 0.003 joules of energy into you. For the above distance, that's 900 GJ. 100 seconds in, and you have experienced pushback equivalent to a nuclear bomb.
Things are a little bit better in the intergalactic medium, where the density is 1 atom per cubic meter, a million times less than in regular interstellar space. That means 900 MJ per second of travel. That's 1 ton of TNT every 5 seconds. Whew, much better!
I'm not even taking into account the possibility that fusion will be undergone for many of these atoms on the surface of your spaceship. Good luck finding a material that can withstand that.
I'm super amateur so I may be miscalculating here, please correct me if I am!
answered May 23 at 0:51
NachtNacht
32117
edited May 23 at 3:12
answered May 23 at 0:51
NachtNacht
32117
answered May 23 at 0:51
NachtNacht
32117
answered May 23 at 0:51
NachtNacht
32117
32117
$begingroup$
At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
$endgroup$
– Nelson
May 23 at 3:07
$begingroup$
Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
$endgroup$
– Nacht
May 23 at 3:19
$begingroup$
Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
$endgroup$
– Luaan
May 23 at 7:29
3
$begingroup$
Obligatory xkcd regarding the possibility of fusion.
$endgroup$
– TypeIA
May 23 at 9:56
$begingroup$
@TypeIA yes, that xkcd heavily inspired this answer
$endgroup$
– Nacht
May 23 at 13:20
add a comment |
$begingroup$
At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
$endgroup$
– Nelson
May 23 at 3:07
$begingroup$
Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
$endgroup$
– Nacht
May 23 at 3:19
$begingroup$
Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
$endgroup$
– Luaan
May 23 at 7:29
3
$begingroup$
Obligatory xkcd regarding the possibility of fusion.
$endgroup$
– TypeIA
May 23 at 9:56
$begingroup$
@TypeIA yes, that xkcd heavily inspired this answer
$endgroup$
– Nacht
May 23 at 13:20
$begingroup$
At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
$endgroup$
– Nelson
May 23 at 3:07
$begingroup$
At relativistic speeds, many things become really big problems. Steering and navigation, for example... the amount of energy required to make the most minute change of direction becomes gigantic.
$endgroup$
– Nelson
May 23 at 3:07
$begingroup$
Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
$endgroup$
– Nacht
May 23 at 3:19
$begingroup$
Yep, my answer is focusing on the specific problem of the sea of matter in what we normally think of as the "vacuum" of space, one of many issues. I just added a paragraph mentioning fusion, but I suspect I may be wrong, would love for someone to correct me there.
$endgroup$
– Nacht
May 23 at 3:19
$begingroup$
Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
$endgroup$
– Luaan
May 23 at 7:29
$begingroup$
Not just the interstellar medium - even the microwave background radiation becomes quite deadly as it is blue-shifted due to your massive speed. There are solutions to this even in hard sci-fi (a popular one being a combination of whipple shields and pushing a massive ice comet in front of your spaceship), but it's all in the "not technically impossible, but don't hold your breath" category.
$endgroup$
– Luaan
May 23 at 7:29
3
3
$begingroup$
Obligatory xkcd regarding the possibility of fusion.
$endgroup$
– TypeIA
May 23 at 9:56
$begingroup$
Obligatory xkcd regarding the possibility of fusion.
$endgroup$
– TypeIA
May 23 at 9:56
$begingroup$
@TypeIA yes, that xkcd heavily inspired this answer
$endgroup$
– Nacht
May 23 at 13:20
$begingroup$
@TypeIA yes, that xkcd heavily inspired this answer
$endgroup$
– Nacht
May 23 at 13:20
add a comment |
$begingroup$
In addition to the other conceptual aspects, there are practical ones.
If you accelerate at 1g for 5 years, then you'll end up x light years away, where x is going to be tedious to compute (I assume you integrate tanh((9.81 m/s^2)*(5 years)/c)), but is clearly going to be measured in *light-years*.
So you're clearly enitrely isolated from the earth, and in the middle of space.
You can't actually do anything interesting with the fact that you're "in the future", because out in space nothing's really happened. In order for it to be at all interesting you'd have to come back to Earth.
But you're also travelling at 0.999934479 c. Away from Earth
Now you have to turn around, and decelerate for 5 years to stop, and then spend another 10 years coming back.
So this 5 year trip, has turned into a 20 year trip, during which your space station has to be entirely self-sufficient ... and not have any problems.
We just don't have the systems to support an environment like that for that long.
Then you've got the psychological and sociological issues to take into account.
Plus the fact that you can't steer this thing.
I can imagine all of these problems being soluble, if we can create a high-10s of personnel space station.
But a) we haven't currently achieved that and I don't think we're anywhere plausibly near achieving that, and b) suddenly the numbers in Thomas Fritsch's answer aren't starting from 1,000kg, they're starting 1,000 tonnes or more!
answered May 23 at 5:57
BrondahlBrondahl
21317
$endgroup$
$begingroup$
There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
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– Luaan
May 23 at 7:32
$begingroup$
@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
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– Brondahl
May 23 at 7:33
4
$begingroup$
And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
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– Brondahl
May 23 at 7:33
2
$begingroup$
@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
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– Chronocidal
May 23 at 12:00
$begingroup$
Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
$endgroup$
– Luaan
May 24 at 6:19
add a comment |
$begingroup$
In addition to the other conceptual aspects, there are practical ones.
If you accelerate at 1g for 5 years, then you'll end up x light years away, where x is going to be tedious to compute (I assume you integrate tanh((9.81 m/s^2)*(5 years)/c)), but is clearly going to be measured in *light-years*.
So you're clearly enitrely isolated from the earth, and in the middle of space.
You can't actually do anything interesting with the fact that you're "in the future", because out in space nothing's really happened. In order for it to be at all interesting you'd have to come back to Earth.
But you're also travelling at 0.999934479 c. Away from Earth
Now you have to turn around, and decelerate for 5 years to stop, and then spend another 10 years coming back.
So this 5 year trip, has turned into a 20 year trip, during which your space station has to be entirely self-sufficient ... and not have any problems.
We just don't have the systems to support an environment like that for that long.
Then you've got the psychological and sociological issues to take into account.
Plus the fact that you can't steer this thing.
I can imagine all of these problems being soluble, if we can create a high-10s of personnel space station.
But a) we haven't currently achieved that and I don't think we're anywhere plausibly near achieving that, and b) suddenly the numbers in Thomas Fritsch's answer aren't starting from 1,000kg, they're starting 1,000 tonnes or more!
answered May 23 at 5:57
BrondahlBrondahl
21317
$endgroup$
$begingroup$
There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
$endgroup$
– Luaan
May 23 at 7:32
$begingroup$
@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
$endgroup$
– Brondahl
May 23 at 7:33
4
$begingroup$
And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
$endgroup$
– Brondahl
May 23 at 7:33
2
$begingroup$
@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
$endgroup$
– Chronocidal
May 23 at 12:00
$begingroup$
Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
$endgroup$
– Luaan
May 24 at 6:19
add a comment |
$begingroup$
In addition to the other conceptual aspects, there are practical ones.
If you accelerate at 1g for 5 years, then you'll end up x light years away, where x is going to be tedious to compute (I assume you integrate tanh((9.81 m/s^2)*(5 years)/c)), but is clearly going to be measured in *light-years*.
So you're clearly enitrely isolated from the earth, and in the middle of space.
You can't actually do anything interesting with the fact that you're "in the future", because out in space nothing's really happened. In order for it to be at all interesting you'd have to come back to Earth.
But you're also travelling at 0.999934479 c. Away from Earth
Now you have to turn around, and decelerate for 5 years to stop, and then spend another 10 years coming back.
So this 5 year trip, has turned into a 20 year trip, during which your space station has to be entirely self-sufficient ... and not have any problems.
We just don't have the systems to support an environment like that for that long.
Then you've got the psychological and sociological issues to take into account.
Plus the fact that you can't steer this thing.
I can imagine all of these problems being soluble, if we can create a high-10s of personnel space station.
But a) we haven't currently achieved that and I don't think we're anywhere plausibly near achieving that, and b) suddenly the numbers in Thomas Fritsch's answer aren't starting from 1,000kg, they're starting 1,000 tonnes or more!
answered May 23 at 5:57
BrondahlBrondahl
21317
$endgroup$
In addition to the other conceptual aspects, there are practical ones.
If you accelerate at 1g for 5 years, then you'll end up x light years away, where x is going to be tedious to compute (I assume you integrate tanh((9.81 m/s^2)*(5 years)/c)), but is clearly going to be measured in *light-years*.
So you're clearly enitrely isolated from the earth, and in the middle of space.
You can't actually do anything interesting with the fact that you're "in the future", because out in space nothing's really happened. In order for it to be at all interesting you'd have to come back to Earth.
But you're also travelling at 0.999934479 c. Away from Earth
Now you have to turn around, and decelerate for 5 years to stop, and then spend another 10 years coming back.
So this 5 year trip, has turned into a 20 year trip, during which your space station has to be entirely self-sufficient ... and not have any problems.
We just don't have the systems to support an environment like that for that long.
Then you've got the psychological and sociological issues to take into account.
Plus the fact that you can't steer this thing.
I can imagine all of these problems being soluble, if we can create a high-10s of personnel space station.
But a) we haven't currently achieved that and I don't think we're anywhere plausibly near achieving that, and b) suddenly the numbers in Thomas Fritsch's answer aren't starting from 1,000kg, they're starting 1,000 tonnes or more!
answered May 23 at 5:57
BrondahlBrondahl
21317
answered May 23 at 5:57
BrondahlBrondahl
21317
answered May 23 at 5:57
BrondahlBrondahl
21317
answered May 23 at 5:57
BrondahlBrondahl
21317
21317
$begingroup$
There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
$endgroup$
– Luaan
May 23 at 7:32
$begingroup$
@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
$endgroup$
– Brondahl
May 23 at 7:33
4
$begingroup$
And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
$endgroup$
– Brondahl
May 23 at 7:33
2
$begingroup$
@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
$endgroup$
– Chronocidal
May 23 at 12:00
$begingroup$
Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
$endgroup$
– Luaan
May 24 at 6:19
add a comment |
$begingroup$
There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
$endgroup$
– Luaan
May 23 at 7:32
$begingroup$
@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
$endgroup$
– Brondahl
May 23 at 7:33
4
$begingroup$
And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
$endgroup$
– Brondahl
May 23 at 7:33
2
$begingroup$
@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
$endgroup$
– Chronocidal
May 23 at 12:00
$begingroup$
Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
$endgroup$
– Luaan
May 24 at 6:19
$begingroup$
There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
$endgroup$
– Luaan
May 23 at 7:32
$begingroup$
There's been proposals to use the magnetic fields in space to turn the spaceship around, at least - though obviously you need to make quite a large turn (probably decades for a high-relativistic spaceship). And you still need to have some way to come to a stop when you get back to Earth, which is one thing you missed :P
$endgroup$
– Luaan
May 23 at 7:32
$begingroup$
@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
$endgroup$
– Brondahl
May 23 at 7:33
$begingroup$
@Luaan do you mean that the 5 years would be in a curve, not in a straight line?
$endgroup$
– Brondahl
May 23 at 7:33
4
4
$begingroup$
And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
$endgroup$
– Brondahl
May 23 at 7:33
$begingroup$
And no I didn't miss slowly down ... it's right there in the answer. 5 years out accelerating, 5 years slowing down. Then 10 years back, speeding up and slowing down.
$endgroup$
– Brondahl
May 23 at 7:33
2
2
$begingroup$
@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
$endgroup$
– Chronocidal
May 23 at 12:00
$begingroup$
@Luaan At 0.99c, I hope he misses - otherwise it'll make Chicxulub look like a love-tap!
$endgroup$
– Chronocidal
May 23 at 12:00
$begingroup$
Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
$endgroup$
– Luaan
May 24 at 6:19
$begingroup$
Some part of it would be a curve, but I expect it'd take a lot longer than five years :D It's hard to get much data on this, since it's a largely forgotten hard sci-fi concept. Also, if you want to "travel to the future", you probably want to spend some time at those high-relativistic speeds, so you'll want to coast for much of the way (hopefully while able to use that magnetic turn thingy to change your course back to Earth, but I'm not sure about the speed limits there).
$endgroup$
– Luaan
May 24 at 6:19
add a comment |
$begingroup$
Mission time.
One of the issues of a manned Mars missions is the time window for an optimal transfer. I takes about six months to get to Mars. If you want to leave for the Earth again using the same window, you have about 10 days to visit Mars.
That's the equivalent of flying from London to New York, visiting the tourist shop for 30 minutes, and then flying back.
But the next window is about 1.5 years later. If you take this window, including travel time to and from, that the mission will take about 2.5 years in isolation and close quarters.
We have no accurate data on the effect of being isolated and contained for such a period, and it is not as easy as you think. There is no way of reaching them or providing supplies. They need to be self-contained and handle all obstacles (e.g. mechanical failures) themselves.
Your proposed experiment would take twice as long. What you've also not accounted for is that the craft needs to slow down again, which would take another 5 years, making the whole mission four times longer than a Mars mission, which is already stretching the boundaries of what we are able to reliably achieve.
It's even worse than a Mars mission, because a Mars mission at least has radio contact. But as the crew gets exposed to time dilation (which will be noticeable much before they reach light speed) communication will become less feasible, and they will be truly alone.
Distance.
Travelling at high velocity (it doesn't even need to be near lightspeed) means that this craft cannot orbit the Earth anymore. So where will it travel? Well, you'd expect them to be about 2.5 lightyears removed from us (on average, they travelled at half of lightspeed during their 5 year speed up = 2.5 lightyears).
But don't forget to account for the slowdown. That's another 2.5 lightyears before they come to a "standstill" (if there were such a thing).
To put it into perspective, that's about 120% the distance to Alpha Centauri.
What's the point?
Okay, so let's say we accomplish all that and send the mission. Then what? They are in the future, out past Alpha Centauri, with no hopes of coming back and dwindling supplies. We can't find out what they experienced. We can't find out anything. There is no benefit to us whatsoever.
This is pretty much the equivalent of shooting a single person in a spacesuit in a particular direction with no comms or any way to get back. You're just sending someone out to a lonely death. You're not accomplishing anything.
And given the amount of time they will have traversed (keep in mind that time dilation will happen relative to their speed, so they will already experience more than half the time dilation for the last 2.5 years of their speed up time), it's likely that the humans alive then will have found other and better way to confirm relativistic effects.
So either the astronauts sacrificed themselves without contributing to the civilization that sent them; or they get picked up by a civilization that has already figured out the thing they gave their lives in pursuit of finding out. Neither is a good outcome.
answered May 23 at 8:40
FlaterFlater
1114
$endgroup$
$begingroup$
I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
$endgroup$
– Brondahl
May 23 at 13:35
$begingroup$
@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
$endgroup$
– Flater
May 23 at 13:38
add a comment |
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Mission time.
One of the issues of a manned Mars missions is the time window for an optimal transfer. I takes about six months to get to Mars. If you want to leave for the Earth again using the same window, you have about 10 days to visit Mars.
That's the equivalent of flying from London to New York, visiting the tourist shop for 30 minutes, and then flying back.
But the next window is about 1.5 years later. If you take this window, including travel time to and from, that the mission will take about 2.5 years in isolation and close quarters.
We have no accurate data on the effect of being isolated and contained for such a period, and it is not as easy as you think. There is no way of reaching them or providing supplies. They need to be self-contained and handle all obstacles (e.g. mechanical failures) themselves.
Your proposed experiment would take twice as long. What you've also not accounted for is that the craft needs to slow down again, which would take another 5 years, making the whole mission four times longer than a Mars mission, which is already stretching the boundaries of what we are able to reliably achieve.
It's even worse than a Mars mission, because a Mars mission at least has radio contact. But as the crew gets exposed to time dilation (which will be noticeable much before they reach light speed) communication will become less feasible, and they will be truly alone.
Distance.
Travelling at high velocity (it doesn't even need to be near lightspeed) means that this craft cannot orbit the Earth anymore. So where will it travel? Well, you'd expect them to be about 2.5 lightyears removed from us (on average, they travelled at half of lightspeed during their 5 year speed up = 2.5 lightyears).
But don't forget to account for the slowdown. That's another 2.5 lightyears before they come to a "standstill" (if there were such a thing).
To put it into perspective, that's about 120% the distance to Alpha Centauri.
What's the point?
Okay, so let's say we accomplish all that and send the mission. Then what? They are in the future, out past Alpha Centauri, with no hopes of coming back and dwindling supplies. We can't find out what they experienced. We can't find out anything. There is no benefit to us whatsoever.
This is pretty much the equivalent of shooting a single person in a spacesuit in a particular direction with no comms or any way to get back. You're just sending someone out to a lonely death. You're not accomplishing anything.
And given the amount of time they will have traversed (keep in mind that time dilation will happen relative to their speed, so they will already experience more than half the time dilation for the last 2.5 years of their speed up time), it's likely that the humans alive then will have found other and better way to confirm relativistic effects.
So either the astronauts sacrificed themselves without contributing to the civilization that sent them; or they get picked up by a civilization that has already figured out the thing they gave their lives in pursuit of finding out. Neither is a good outcome.
answered May 23 at 8:40
FlaterFlater
1114
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I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
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– Brondahl
May 23 at 13:35
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@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
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– Flater
May 23 at 13:38
add a comment |
$begingroup$
Mission time.
One of the issues of a manned Mars missions is the time window for an optimal transfer. I takes about six months to get to Mars. If you want to leave for the Earth again using the same window, you have about 10 days to visit Mars.
That's the equivalent of flying from London to New York, visiting the tourist shop for 30 minutes, and then flying back.
But the next window is about 1.5 years later. If you take this window, including travel time to and from, that the mission will take about 2.5 years in isolation and close quarters.
We have no accurate data on the effect of being isolated and contained for such a period, and it is not as easy as you think. There is no way of reaching them or providing supplies. They need to be self-contained and handle all obstacles (e.g. mechanical failures) themselves.
Your proposed experiment would take twice as long. What you've also not accounted for is that the craft needs to slow down again, which would take another 5 years, making the whole mission four times longer than a Mars mission, which is already stretching the boundaries of what we are able to reliably achieve.
It's even worse than a Mars mission, because a Mars mission at least has radio contact. But as the crew gets exposed to time dilation (which will be noticeable much before they reach light speed) communication will become less feasible, and they will be truly alone.
Distance.
Travelling at high velocity (it doesn't even need to be near lightspeed) means that this craft cannot orbit the Earth anymore. So where will it travel? Well, you'd expect them to be about 2.5 lightyears removed from us (on average, they travelled at half of lightspeed during their 5 year speed up = 2.5 lightyears).
But don't forget to account for the slowdown. That's another 2.5 lightyears before they come to a "standstill" (if there were such a thing).
To put it into perspective, that's about 120% the distance to Alpha Centauri.
What's the point?
Okay, so let's say we accomplish all that and send the mission. Then what? They are in the future, out past Alpha Centauri, with no hopes of coming back and dwindling supplies. We can't find out what they experienced. We can't find out anything. There is no benefit to us whatsoever.
This is pretty much the equivalent of shooting a single person in a spacesuit in a particular direction with no comms or any way to get back. You're just sending someone out to a lonely death. You're not accomplishing anything.
And given the amount of time they will have traversed (keep in mind that time dilation will happen relative to their speed, so they will already experience more than half the time dilation for the last 2.5 years of their speed up time), it's likely that the humans alive then will have found other and better way to confirm relativistic effects.
So either the astronauts sacrificed themselves without contributing to the civilization that sent them; or they get picked up by a civilization that has already figured out the thing they gave their lives in pursuit of finding out. Neither is a good outcome.
answered May 23 at 8:40
FlaterFlater
1114
$endgroup$
Mission time.
One of the issues of a manned Mars missions is the time window for an optimal transfer. I takes about six months to get to Mars. If you want to leave for the Earth again using the same window, you have about 10 days to visit Mars.
That's the equivalent of flying from London to New York, visiting the tourist shop for 30 minutes, and then flying back.
But the next window is about 1.5 years later. If you take this window, including travel time to and from, that the mission will take about 2.5 years in isolation and close quarters.
We have no accurate data on the effect of being isolated and contained for such a period, and it is not as easy as you think. There is no way of reaching them or providing supplies. They need to be self-contained and handle all obstacles (e.g. mechanical failures) themselves.
Your proposed experiment would take twice as long. What you've also not accounted for is that the craft needs to slow down again, which would take another 5 years, making the whole mission four times longer than a Mars mission, which is already stretching the boundaries of what we are able to reliably achieve.
It's even worse than a Mars mission, because a Mars mission at least has radio contact. But as the crew gets exposed to time dilation (which will be noticeable much before they reach light speed) communication will become less feasible, and they will be truly alone.
Distance.
Travelling at high velocity (it doesn't even need to be near lightspeed) means that this craft cannot orbit the Earth anymore. So where will it travel? Well, you'd expect them to be about 2.5 lightyears removed from us (on average, they travelled at half of lightspeed during their 5 year speed up = 2.5 lightyears).
But don't forget to account for the slowdown. That's another 2.5 lightyears before they come to a "standstill" (if there were such a thing).
To put it into perspective, that's about 120% the distance to Alpha Centauri.
What's the point?
Okay, so let's say we accomplish all that and send the mission. Then what? They are in the future, out past Alpha Centauri, with no hopes of coming back and dwindling supplies. We can't find out what they experienced. We can't find out anything. There is no benefit to us whatsoever.
This is pretty much the equivalent of shooting a single person in a spacesuit in a particular direction with no comms or any way to get back. You're just sending someone out to a lonely death. You're not accomplishing anything.
And given the amount of time they will have traversed (keep in mind that time dilation will happen relative to their speed, so they will already experience more than half the time dilation for the last 2.5 years of their speed up time), it's likely that the humans alive then will have found other and better way to confirm relativistic effects.
So either the astronauts sacrificed themselves without contributing to the civilization that sent them; or they get picked up by a civilization that has already figured out the thing they gave their lives in pursuit of finding out. Neither is a good outcome.
answered May 23 at 8:40
FlaterFlater
1114
edited May 23 at 8:46
answered May 23 at 8:40
FlaterFlater
1114
answered May 23 at 8:40
FlaterFlater
1114
answered May 23 at 8:40
FlaterFlater
1114
1114
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I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
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– Brondahl
May 23 at 13:35
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@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
$endgroup$
– Flater
May 23 at 13:38
add a comment |
$begingroup$
I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
$endgroup$
– Brondahl
May 23 at 13:35
$begingroup$
@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
$endgroup$
– Flater
May 23 at 13:38
$begingroup$
I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
$endgroup$
– Brondahl
May 23 at 13:35
$begingroup$
I don't think it will be 2.5 light-years, because I don't think the acceleration will be constant (from the earths f.o.r.)
$endgroup$
– Brondahl
May 23 at 13:35
$begingroup$
@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
$endgroup$
– Flater
May 23 at 13:38
$begingroup$
@Brondahl: It was a back of the napkin approximation. The point wasn't so much the precision of it but rather the approximate order of magnitude.
$endgroup$
– Flater
May 23 at 13:38
add a comment |
$begingroup$
The only current propulsion systems, that I know of, that could achieve high speeds is the same one they've been talking about for decades, setting off nuclear bombs behind a pusher plate. However, I heard somewhere that this would only be feasible for about 10% of the speed of light. And, like in the other answers, you would have to have protection from incoming atoms in space.
answered May 23 at 14:24
James MontagneJames Montagne
15
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add a comment |
$begingroup$
The only current propulsion systems, that I know of, that could achieve high speeds is the same one they've been talking about for decades, setting off nuclear bombs behind a pusher plate. However, I heard somewhere that this would only be feasible for about 10% of the speed of light. And, like in the other answers, you would have to have protection from incoming atoms in space.
answered May 23 at 14:24
James MontagneJames Montagne
15
$endgroup$
add a comment |
$begingroup$
The only current propulsion systems, that I know of, that could achieve high speeds is the same one they've been talking about for decades, setting off nuclear bombs behind a pusher plate. However, I heard somewhere that this would only be feasible for about 10% of the speed of light. And, like in the other answers, you would have to have protection from incoming atoms in space.
answered May 23 at 14:24
James MontagneJames Montagne
15
$endgroup$
The only current propulsion systems, that I know of, that could achieve high speeds is the same one they've been talking about for decades, setting off nuclear bombs behind a pusher plate. However, I heard somewhere that this would only be feasible for about 10% of the speed of light. And, like in the other answers, you would have to have protection from incoming atoms in space.
answered May 23 at 14:24
James MontagneJames Montagne
15
edited May 28 at 17:31
answered May 23 at 14:24
James MontagneJames Montagne
15
answered May 23 at 14:24
James MontagneJames Montagne
15
answered May 23 at 14:24
James MontagneJames Montagne
15
15
add a comment |
add a comment |
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Comments are not for extended discussion; this conversation has been moved to chat.
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– Chris♦
May 22 at 19:12
3
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How is this different from the many other ways that show relativity in action, such as gravitational lensing? Besides, I expect to be travelling into the future later this evening, as do many others, so why is that special?
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– Don Branson
May 23 at 2:26
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@DanBranson: get me a beer while you're there? Thanks. :-)
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– Bob Jarvis
May 23 at 4:00