Two Hitchhiker's-Guide-to-the-Galaxy-style presentations of the awesome (and humbling) aspects of intergalactic travel. Possible solutions to the Fermi Paradox are presented here.
Looks like your video link is broken. Something few people realize is there isn't actually a limit on the speed of space travel from the perspective of the traveller. Therefore accelerating a 1g constantly one can easily travel to anywhere in the Milkyway within your lifespan. The limit on such travel is not the speed of light which doesn't apply to the traveler (only to outside observers). THe actual limit is bringin enough propellant to sustain 1g for many years. This is why the the very strange, very dubious, but not yet scientifically dismissed EM drive is of such potential importance. If it turns out it's not a colossal scientific error, then a reaction-less drive has been discovered that needs no propellant. It defies common physics but some recent astrophysical theories may accept it as possible. Does the drove work? tests say yes but huge doubts remain to be ironed out.
Actually, the speed of light _is_ the limit, because as matter is accelerated toward c, its _mass_ increases, and you need ever more energy to push it even a smidgen faster; it becomes a losing game. This increase in mass has been seen in tests.
Time dilation would still be an issue. While you might take only 30 years in your craft to get other to the other side of the galaxy, the rest of the galaxy would have experienced 10's of thousands of years and the larger universe would indeed have expanded and everything will be further apart on the grand cosmic scale. The limits as per the video hold up.
These are wonderful. Thank you for passing them along. One question I had after watching the first video was are we seeing the whole universe or have parts of it already gone too far for the photons to make it back. I'm guessing there's an explanation I could dig up if I weren't on my way to work :) Maybe it's embodied in the phrase "observable universe."
No. It is not impossible. The author clearly means something odd by "... moving away from us at speeds we cannot hope to match." (I have asked for clarification).
The Wikipedia article on Maffei One (in the Maffei cluster, the next one over) indicates that it is about 3 megaparsecs away (call that 10,000,000 light years) and receding at from the center of mass of our local group at ~300 km/s.
That is quite far indeed and to make matters worse the expansion is accelerating so we can expect that rate it moves away increase during the journey. Lets call the rate of expansion 75 kilometers per second per megaparsec. The saving grace is that there is theoretically no reason we cannot travel at speeds near 300,000 km/sec so you can still make it. (i.e. Maffei One is well well within the Hubble Length where traveling near the speed of light it is reachable.)
I don't see that most of the local super-cluster isn't in principle reachable if we get on our game, convert ourselves to non-meat based bodies, and leave at very high speeds in the next million years or so.
Looks like your video link is broken. Something few people realize is there isn't actually a limit on the speed of space travel from the perspective of the traveller. Therefore accelerating a 1g constantly one can easily travel to anywhere in the Milkyway within your lifespan. The limit on such travel is not the speed of light which doesn't apply to the traveler (only to outside observers). THe actual limit is bringin enough propellant to sustain 1g for many years. This is why the the very strange, very dubious, but not yet scientifically dismissed EM drive is of such potential importance. If it turns out it's not a colossal scientific error, then a reaction-less drive has been discovered that needs no propellant. It defies common physics but some recent astrophysical theories may accept it as possible. Does the drove work? tests say yes but huge doubts remain to be ironed out.
ReplyDeleteAll the links work for me. You may be traveling too fast to access them.
DeleteActually, the speed of light _is_ the limit, because as matter is accelerated toward c, its _mass_ increases, and you need ever more energy to push it even a smidgen faster; it becomes a losing game. This increase in mass has been seen in tests.
DeleteLurker111
Time dilation would still be an issue. While you might take only 30 years in your craft to get other to the other side of the galaxy, the rest of the galaxy would have experienced 10's of thousands of years and the larger universe would indeed have expanded and everything will be further apart on the grand cosmic scale. The limits as per the video hold up.
DeleteThese are wonderful. Thank you for passing them along. One question I had after watching the first video was are we seeing the whole universe or have parts of it already gone too far for the photons to make it back. I'm guessing there's an explanation I could dig up if I weren't on my way to work :) Maybe it's embodied in the phrase "observable universe."
ReplyDeleteFascinating stuff indeed, thanks again for showing me things I would have missed if yuo hadn't pointed them out.
ReplyDeleteNo. It is not impossible. The author clearly means something odd by "... moving away from us at speeds we cannot hope to match." (I have asked for clarification).
ReplyDeleteThe Wikipedia article on Maffei One (in the Maffei cluster, the next one over) indicates that it is about 3 megaparsecs away (call that 10,000,000 light years) and receding at from the center of mass of our local group at ~300 km/s.
That is quite far indeed and to make matters worse the expansion is accelerating so we can expect that rate it moves away increase during the journey. Lets call the rate of expansion 75 kilometers per second per megaparsec. The saving grace is that there is theoretically no reason we cannot travel at speeds near 300,000 km/sec so you can still make it. (i.e. Maffei One is well well within the Hubble Length where traveling near the speed of light it is reachable.)
I don't see that most of the local super-cluster isn't in principle reachable if we get on our game, convert ourselves to non-meat based bodies, and leave at very high speeds in the next million years or so.
I have to look into this more. Something isn't quite right in my understanding here.
Delete