I Am Fascinated By Space Science
Will it be possible to travel between galaxies for human oneday?
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canadarm · M
Not physically, no. Our Galaxy alone is 100,000 lightyears across so even at lightspeed it would take 100,000 years just to get across OUR galaxy!
canadarm · M
@Sharon: we are still talking 2.5 million years at the speed of light to the NEAREST galaxy lol!!
The problem even if one could achieve such velocities is, over such a long distance, the possibility of impacting even a speck of matter would be disastrous.
So called "empty" space is populated by plenty of these micro objects and avoiding hitting even a frame-referenced "stationary" one would require either such energetic shielding it would rival the propulsion system, or exotic materials capable of deflecting such objects, never mind something as massive as a plain meteorite.
The problem even if one could achieve such velocities is, over such a long distance, the possibility of impacting even a speck of matter would be disastrous.
So called "empty" space is populated by plenty of these micro objects and avoiding hitting even a frame-referenced "stationary" one would require either such energetic shielding it would rival the propulsion system, or exotic materials capable of deflecting such objects, never mind something as massive as a plain meteorite.
Sharon · F
@canadarm: You're ignoring the time dilation effect. See - https://en.wikipedia.org/wiki/Time_dilation
I take your point about banging into things, some method of deflecting other objects would need to be found.
I take your point about banging into things, some method of deflecting other objects would need to be found.
canadarm · M
@Sharon: no I did consider that, but A: it is significant only approaching lightspeed and B: we are still talking about 2.5 MILLION lightyears not just 100,000.
One of the reasons a physical object can not approach lightspeed is because the energy ( fuel etc) to do so would constitute almost all of its mass. As it expends the mass of fuel it then GAINS MASS due to velocity.
This becomes a self-defeating equation.
A physical object ( ie spacecraft) could not possibly carry enough energy (mass) to achieve any speeds at which time dilation would significantly offset the tremendous distance involved.
One of the reasons a physical object can not approach lightspeed is because the energy ( fuel etc) to do so would constitute almost all of its mass. As it expends the mass of fuel it then GAINS MASS due to velocity.
This becomes a self-defeating equation.
A physical object ( ie spacecraft) could not possibly carry enough energy (mass) to achieve any speeds at which time dilation would significantly offset the tremendous distance involved.
Sharon · F
At 0.99999999999999c you could cover 2 500 000 lightyears in about 4 months of your (spaceship's) time. I accept that's really shifting and getting to that speed would need some improvement in current engine technology. ;)
I'm aware of relativistic mass and take your point about fuel consumption. Have you done the maths? I would be interesting to see the actual figures. Even if the craft could not carry enough fuel when it sets off, perhaps it would be possible to re-fuel in some way while in flight.
There is also the possibility of wormholes.
The theory allows for inter-galactic travel, only the current technology holds us back.
I'm aware of relativistic mass and take your point about fuel consumption. Have you done the maths? I would be interesting to see the actual figures. Even if the craft could not carry enough fuel when it sets off, perhaps it would be possible to re-fuel in some way while in flight.
There is also the possibility of wormholes.
The theory allows for inter-galactic travel, only the current technology holds us back.
canadarm · M
@Sharon: you are grasping at hypothetical sci fi straws.
Refueling an in-flight sub-lightspeed craft requires ANOTHER sub-lightspeed craft, bearing yet more fuel than it needs to propel itself, thus carrying even more mass.
There is no such thing as a wormhole.
It is a mathematical construct and has no counterpart in reality.
Theories can allow for anything.
The purpose of a theory in Science is the explanation of an observed phenomenon, not the proposal of any kind of dreamed-up reality.
No mathematics is required to support logic.
If you doubt this, investigate the works of Niels Bohr who gave us the the Standard Model of the Atom and had not a single Fornula among his life's work.
Similarly Einstein resisted the imposition of mathematics upon actual descriptions of reality because he understood that Mathematics becomes its own
Hypothetical Reality.
This is what we call THEORETICAL Physics, and why we call it that.
Refueling an in-flight sub-lightspeed craft requires ANOTHER sub-lightspeed craft, bearing yet more fuel than it needs to propel itself, thus carrying even more mass.
There is no such thing as a wormhole.
It is a mathematical construct and has no counterpart in reality.
Theories can allow for anything.
The purpose of a theory in Science is the explanation of an observed phenomenon, not the proposal of any kind of dreamed-up reality.
No mathematics is required to support logic.
If you doubt this, investigate the works of Niels Bohr who gave us the the Standard Model of the Atom and had not a single Fornula among his life's work.
Similarly Einstein resisted the imposition of mathematics upon actual descriptions of reality because he understood that Mathematics becomes its own
Hypothetical Reality.
This is what we call THEORETICAL Physics, and why we call it that.
Sharon · F
By re-fueling I simply mean transferring energy to the craft. It might be possible to do that via electromagnetic radiaton.
Scientific theories (as opposed to hypotheses) are tested and found to conform to the observed facts.
GR predicts wormholes just as it predicted black holes. We've discovered black holes; it might just be a matter of time before we discover wormholes. The time dilation effect is just a theory but has been proven to be true.
Physical objects do approach lightspeeds. Any speed is closer to the speed of light than stationary. The question is whether something large engough to carry passengers can be accelerated to a speed where the time dilation effect would be significant - mathematics would tell us that. You're proposing a sub-light speed that no physical object can be accelerated to. What is that speed?
My point is simply that proven scientific theory allows for inter-galactic travel. I'm not suggesting it would be easy to accomplish, just that we can't say it's impossible and will forever remain unachievable.
Scientific theories (as opposed to hypotheses) are tested and found to conform to the observed facts.
GR predicts wormholes just as it predicted black holes. We've discovered black holes; it might just be a matter of time before we discover wormholes. The time dilation effect is just a theory but has been proven to be true.
Physical objects do approach lightspeeds. Any speed is closer to the speed of light than stationary. The question is whether something large engough to carry passengers can be accelerated to a speed where the time dilation effect would be significant - mathematics would tell us that. You're proposing a sub-light speed that no physical object can be accelerated to. What is that speed?
My point is simply that proven scientific theory allows for inter-galactic travel. I'm not suggesting it would be easy to accomplish, just that we can't say it's impossible and will forever remain unachievable.
canadarm · M
@Sharon: [image deleted]
In answer to your question "what is that speed?"
My answer is "sufficient speed that would allow Time Dilation to affect the mission".
As you can see from the graph, there is not much action in TD until you get to about 1/2 c. You would need to go MUCH faster because the increase of TD is not linear with increased velocity.
Now about wormholes.
Even if there was conveniently an opening here and the exit near Andromeda: the fastest way down the river is over the waterfall!
In other words, like a black hole, we might not survive the encounter.
The forgotten aspect is Time.
We see Andromeda as it was 2.5 million years ago.
Even if we got there INSTANTLY right now: we would arrive at a galaxy evolved 2.5 million years from our initial view.
It could be long gone!
( unlikely but you see my point).
The farther out we look the longer ago it is.
The objects of our destination could be ancient history right now.
In answer to your question "what is that speed?"
My answer is "sufficient speed that would allow Time Dilation to affect the mission".
As you can see from the graph, there is not much action in TD until you get to about 1/2 c. You would need to go MUCH faster because the increase of TD is not linear with increased velocity.
Now about wormholes.
Even if there was conveniently an opening here and the exit near Andromeda: the fastest way down the river is over the waterfall!
In other words, like a black hole, we might not survive the encounter.
The forgotten aspect is Time.
We see Andromeda as it was 2.5 million years ago.
Even if we got there INSTANTLY right now: we would arrive at a galaxy evolved 2.5 million years from our initial view.
It could be long gone!
( unlikely but you see my point).
The farther out we look the longer ago it is.
The objects of our destination could be ancient history right now.
Sharon · F
@canadarm: I do know the equation but thanks for the graph, I couldn't find it immediately when I took a quick look for it.
I won't argue the science with you, I think we agree even at 0.5c TD is minimal, the effect only becomes useful at speeds much higher than that - 0.8c and greater I'd say.
I also accept wormholes are not likely to be a practical proposition. We'd need to either find a natural one with openings where we want them or contruct one artificially. Even if we find a way, constructing the other end could prove challenging. Also, as you say, where we want to go might not be there now.
I've raised that last point myself in relation to SETI. If we do detect signs of extra-terrestrial intellegent life, it will be as it was some considerable time ago.
Something else I hope we can agree on, physics is a fascinating subject. :)
I won't argue the science with you, I think we agree even at 0.5c TD is minimal, the effect only becomes useful at speeds much higher than that - 0.8c and greater I'd say.
I also accept wormholes are not likely to be a practical proposition. We'd need to either find a natural one with openings where we want them or contruct one artificially. Even if we find a way, constructing the other end could prove challenging. Also, as you say, where we want to go might not be there now.
I've raised that last point myself in relation to SETI. If we do detect signs of extra-terrestrial intellegent life, it will be as it was some considerable time ago.
Something else I hope we can agree on, physics is a fascinating subject. :)
canadarm · M
@Sharon: yes definitely and thank you for the great discussion.
I think we need our own YouTube Channel lol!
I think we need our own YouTube Channel lol!