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Author Topic:   Is Faster Than Light travel the wrong question?
kbertsche
Member (Idle past 2122 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 16 of 81 (533452)
10-30-2009 7:45 PM
Reply to: Message 15 by Perdition
10-30-2009 2:09 PM


Re: fantasy
quote:
The science at one time said breaking the sound barrier was impossible,
This was no doubt a commonly-held conception, and it was certainly a technological challenge. But can you point to a reference where science said this was impossible?
quote:
As I said earlier in the thread, wormholes, space warping, etc may get us great distances in short times by altering the fabric of space itself to make the trip shorter. While this may seem "far-out" and "fantasy" there are physicists working on this sort of thing.
String theorists are certainly trying to understand these things in a fundamental, theoretical way. But can you point to any physicists who are actually "working on this sort of thing" with a goal "to make the trip shorter" for human transportation?

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 Message 15 by Perdition, posted 10-30-2009 2:09 PM Perdition has replied

Replies to this message:
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onifre
Member (Idle past 2941 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 17 of 81 (533454)
10-31-2009 2:20 AM
Reply to: Message 15 by Perdition
10-30-2009 2:09 PM


Re: fantasy
The science at one time said breaking the sound barrier was impossible, so it's also possible (though I would admit unlikely) that the light speed limit is not quite as absolute as we think it is.
Agreeing as we always do (on most things) it pains me to have to interject - lol. Actually, the speed of light as a constant is a fact of nature; in fact, one could say a law of physics.
I like how a lot of arguments come back to the same line of reasoning; what objective evidence are you using to state that it might not be "absolute," or a constant, as I called it?
- Oni

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 Message 15 by Perdition, posted 10-30-2009 2:09 PM Perdition has replied

Replies to this message:
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Michamus
Member (Idle past 5148 days)
Posts: 230
From: Ft Hood, TX
Joined: 03-16-2009


Message 18 of 81 (533473)
10-31-2009 7:48 AM
Reply to: Message 12 by Aware Wolf
10-30-2009 12:25 PM


This is kind of a reply to everyone, but I picked Aware Wolf as his was the last post that I felt was in in line with my topic (precisely that is. The side discussion on Technology advancements, change in understanding of Physics, and worm-holes/ space dilation-contraction is fascinating) I do wish there was a type of multi-reply function so everyone I selected would receive a notification e-mail, but alas we are limited to what tools we have.
Aware Wolf writes:
Picture a meter stick pointing straight up. This represents an object "standing still" in space in a particular FOR.
This is how things have been explained to me as well. I do have a few statements in regard to it, that I wish Cavediver were here to discuss.
This statement seems to be true (and I will agree with it) but it is just as you said, from a particular FoR. We understand there to be no Universal FoR, as everything is relative. We also understand there to be no such thing as true rest.
With that, from an Earthly FoR, we are at rest, and light is traveling at 300,000km/sec (can't forget the k onifre). Regardless of what direction we point the light beam, it still travels at C, which is why it has that awesome abbreviation for "Constant".
Taking that into consideration we must ask ourselves a few questions.
1. If we point a light beam forward while traveling .999c, is that light beam going to travel back in time? I'd imagine the answer to be no.
2. If we are traveling .999c away from the Earth... and the Earth is traveling at .002c (I know a stretch) are we now really going 1.001c? I'd say no, we are still going .999c relative to the Earth, but at REST relative to ourselves, and light is still going LS.
3. Does time slow as we experience it? That is, do our internal time-keeping mechanisms suddenly experience time slower from our own FoR if we increase our velocity? Do clocks suddenly start ticking slower than before, as per traveler FoR? I'd say the answer is no, time still apparently drudges forward at the same speed to the traveler, regardless his velocity.
So what I see as perplexing is that the meter stick never really changes direction, as you are never really moving (from your FoR). You are constantly at rest (from your FoR), regardless your velocity.
With those taken into consideration, what is really keeping us from going from here to Alpha Centauri in one year, or sooner?

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 Message 20 by cavediver, posted 10-31-2009 8:09 AM Michamus has replied

  
Michamus
Member (Idle past 5148 days)
Posts: 230
From: Ft Hood, TX
Joined: 03-16-2009


Message 19 of 81 (533474)
10-31-2009 8:01 AM
Reply to: Message 5 by kbertsche
10-29-2009 7:34 PM


I understand what you are saying, and it makes sense. My question kind of assumes that we would be at a Stage of Technological Understanding to where manipulating the energy of stars is about as amazing as plugging in a toaster. (That's not a statement of possibility or probability, just a given necessary to discuss the point further)
kbertsche writes:
An acceleration of 1G for 1 year would give a relative velocity of about 0.7 c, and you would age at about 70% the normal rate.
I'm not too sure on the precision of your numbers, but I'll take them on good faith. What exactly would be bad about traveling at 1G for 1 year? We experience 1G all the time for many years... In this scenario I would make the space-craft essentially accelerate floor side down, so you would have gravity in space.
I'd imagine though that kind of acceleration would require quite a bit of energy to be sustained...
kbertsche writes:
The energy expenditure for this would be enormous, of course. That's why sci-fi scenarios of sending people to colonize distant planets are complete fantasy.
Maybe it is, maybe it isn't. I can't see us as being too qualified as to predicting what the future brings. It does seem like an impossible scenario, with the current questions and solutions we are providing.

This message is a reply to:
 Message 5 by kbertsche, posted 10-29-2009 7:34 PM kbertsche has replied

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cavediver
Member (Idle past 3633 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 20 of 81 (533476)
10-31-2009 8:09 AM
Reply to: Message 18 by Michamus
10-31-2009 7:48 AM


that I wish Cavediver were here to discuss.
Oh, I'm here Just VAT return time as ever...
what is really keeping us from going from here to Alpha Centauri in one year, or sooner?
Nothing - if you can accelerate hard enough and safely enough, you can reach Alpha C as fast as you like - couple of days maybe. Of course, your round trip as measured by someone on Earth will take 8.6 years, but you can do it so to age as little as you choose.
Does time slow as we experience it?
I'm not sure what this means. Do you mean, can we see our own watch tick slowly? No, definitely not. You only see those watches that are travelling at speeds relative to your own as ticking slowly (or more quickly in some circumstances)

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 Message 18 by Michamus, posted 10-31-2009 7:48 AM Michamus has replied

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 Message 21 by Michamus, posted 10-31-2009 8:10 AM cavediver has not replied
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Michamus
Member (Idle past 5148 days)
Posts: 230
From: Ft Hood, TX
Joined: 03-16-2009


Message 21 of 81 (533477)
10-31-2009 8:10 AM
Reply to: Message 20 by cavediver
10-31-2009 8:09 AM


WOW! You just completely answered all my questions in a couple sentences.

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kbertsche
Member (Idle past 2122 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 22 of 81 (533510)
10-31-2009 12:49 PM
Reply to: Message 19 by Michamus
10-31-2009 8:01 AM


quote:
I understand what you are saying, and it makes sense. My question kind of assumes that we would be at a Stage of Technological Understanding to where manipulating the energy of stars is about as amazing as plugging in a toaster. (That's not a statement of possibility or probability, just a given necessary to discuss the point further)
Yes, if we were at such a point technologically, such travel would be simple.
quote:
I'm not too sure on the precision of your numbers, but I'll take them on good faith.
They are back-of-the-envelope calculations (literally), and should be accurate to 10% or so.
quote:
What exactly would be bad about traveling at 1G for 1 year? We experience 1G all the time for many years... In this scenario I would make the space-craft essentially accelerate floor side down, so you would have gravity in space.
There's nothing wrong with 1G at all for an entire lifetime, of course. But this only gets you to about 0.7 c after a year, where things are just starting to get relativistic. It would be preferable to accelerate at 2G or more to further reduce the time.
quote:
I'd imagine though that kind of acceleration would require quite a bit of energy to be sustained...
Exactly. This is the fundamental problem. It puts a very high cost on the process, and this would be true for any society where energy cost is at all significant.
These things are fun to speculate about, but they are not realistic in the foreseeable future. They certainly are not realistic until/unless we solve our energy problems. I am frankly surprised at the resistance that such comments meet in this thread. There seems to be a quasi-religious conviction here that mankind will be able to do such things one day. I consider these sci-fi speculations to be in the same vein as (but even less realistic than) global floods or vapor canopies.

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kbertsche
Member (Idle past 2122 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 23 of 81 (533511)
10-31-2009 1:08 PM
Reply to: Message 20 by cavediver
10-31-2009 8:09 AM


quote:
Nothing - if you can accelerate hard enough and safely enough, you can reach Alpha C as fast as you like - couple of days maybe. Of course, your round trip as measured by someone on Earth will take 8.6 years, but you can do it so to age as little as you choose.
Yes, but it's not possible to accelerate hard enough and safely enough to reduce this to a few days. Jet pilots in pressurized suits can endure a few Gs (less than 10?) for very short periods. Even if you could somehow get to 12G's, it would still take a month to get to 0.7 c where things begin to get relativistic.
I invite you guys to check my back-of-the-envelope math. Here's a brief explanation of it:
1G acceleration is about 10 m/s^2. 1 year is about 3x10^7 seconds. So in a non-relativistic world, 1G for 1 year would take you to a velocity of 3x10^8 m/s. This just happens to be the speed of light, making things convenient. We haven't actually gotten to this velocity, of course, because of relativistic effects which we have ignored. But with a fixed force of acceleration for a year, we HAVE imparted the same momentum as in the non-relativistic case, a momentum equal to c times the rest mass (p = m0c). The total energy is then sqrt(2) times the rest energy, and the velocity is 0.7 c.
Edited by kbertsche, : clarified?

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Replies to this message:
 Message 24 by DevilsAdvocate, posted 10-31-2009 1:35 PM kbertsche has replied
 Message 31 by Taz, posted 11-02-2009 1:06 AM kbertsche has replied

  
DevilsAdvocate
Member (Idle past 3091 days)
Posts: 1548
Joined: 06-05-2008


Message 24 of 81 (533515)
10-31-2009 1:35 PM
Reply to: Message 23 by kbertsche
10-31-2009 1:08 PM


If we have enough energy to push a spacecraft to near c velocities I don't think using some of this energy to counteract g-forces would be much of an issue i.e. utilizing a rotating wheel like in 2001: A Space Odyssey, etc.
Correct me if I am wrong.

One of the saddest lessons of history is this: If we've been bamboozled long enough, we tend to reject any evidence of the bamboozle. We're no longer interested in finding out the truth. The bamboozle has captured us. It is simply too painful to acknowledge -- even to ourselves -- that we've been so credulous. - Carl Sagan, The Fine Art of Baloney Detection
"You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe." - Carl Sagan
"It is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring." - Carl Sagan, The Demon-Haunted World

This message is a reply to:
 Message 23 by kbertsche, posted 10-31-2009 1:08 PM kbertsche has replied

Replies to this message:
 Message 25 by kbertsche, posted 10-31-2009 2:22 PM DevilsAdvocate has replied

  
kbertsche
Member (Idle past 2122 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 25 of 81 (533518)
10-31-2009 2:22 PM
Reply to: Message 24 by DevilsAdvocate
10-31-2009 1:35 PM


quote:
If we have enough energy to push a spacecraft to near c velocities I don't think using some of this energy to counteract g-forces would be much of an issue i.e. utilizing a rotating wheel like in 2001: A Space Odyssey, etc.
Correct me if I am wrong.
Centrifugal force from a rotating wheel can only add acceleration; it can't reduce it. This only makes things worse.

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Coyote
Member (Idle past 2096 days)
Posts: 6117
Joined: 01-12-2008


Message 26 of 81 (533523)
10-31-2009 3:19 PM
Reply to: Message 22 by kbertsche
10-31-2009 12:49 PM


Optimistic, not quasi-religious
These things are fun to speculate about, but they are not realistic in the foreseeable future. They certainly are not realistic until/unless we solve our energy problems. I am frankly surprised at the resistance that such comments meet in this thread. There seems to be a quasi-religious conviction here that mankind will be able to do such things one day. I consider these sci-fi speculations to be in the same vein as (but even less realistic than) global floods or vapor canopies.
You are correct about the physics; we don't know how to do efficient interplanetary travel, let alone interstellar travel.
But in the history of science the safe way to bet has always been that something will turn up. Science fiction embodies that optimism.
I think Arthur C. Clarke's three "laws" of prediction would apply here:
  1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
  2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
  3. Any sufficiently advanced technology is indistinguishable from magic.

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

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 Message 22 by kbertsche, posted 10-31-2009 12:49 PM kbertsche has seen this message but not replied

  
DevilsAdvocate
Member (Idle past 3091 days)
Posts: 1548
Joined: 06-05-2008


Message 27 of 81 (533524)
10-31-2009 3:19 PM
Reply to: Message 25 by kbertsche
10-31-2009 2:22 PM


What if the people were somehow able stay on the side of the centrifuge in the direction that the spaceship is moving as opposed to away from it, thus subtracting from rather than adding to the g forces produced by the engines. Maybe a centrifuge inside a centrifuge going in opposite directions? Not sure. Also g-dampening may work i.e. liquids, etc. It sounds convaluted by I am sure someone could figure this out.
Edited by DevilsAdvocate, : No reason given.

One of the saddest lessons of history is this: If we've been bamboozled long enough, we tend to reject any evidence of the bamboozle. We're no longer interested in finding out the truth. The bamboozle has captured us. It is simply too painful to acknowledge -- even to ourselves -- that we've been so credulous. - Carl Sagan, The Fine Art of Baloney Detection
"You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe." - Carl Sagan
"It is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring." - Carl Sagan, The Demon-Haunted World

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 Message 25 by kbertsche, posted 10-31-2009 2:22 PM kbertsche has seen this message but not replied

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DevilsAdvocate
Member (Idle past 3091 days)
Posts: 1548
Joined: 06-05-2008


Message 28 of 81 (533526)
10-31-2009 3:57 PM
Reply to: Message 27 by DevilsAdvocate
10-31-2009 3:19 PM


I know this is far fetched but what if there is a cabin inside the centrifuge that spins independently of the centrifuge and maintains a position on the side of the spaceship opposed to the g-forces caused by the accelerating engines. The capsule would still be subject to the negative g-force (in relation to the g-forces towards the engine) of the centrifuge thus helping to damnpen the excessive g-forces towards the engine.
Of course getting this all to work would be incredibly complex and the centrifuge would have to spin at incredibly high speeds. If there were a malfunction God help the crew because if they are accelerating faster than 10-11 g's they probably would not survive. Also this would all need to reverse when the ship began deccelerating.
Any thoughts if this could hypothetically work?
Edited by DevilsAdvocate, : No reason given.

One of the saddest lessons of history is this: If we've been bamboozled long enough, we tend to reject any evidence of the bamboozle. We're no longer interested in finding out the truth. The bamboozle has captured us. It is simply too painful to acknowledge -- even to ourselves -- that we've been so credulous. - Carl Sagan, The Fine Art of Baloney Detection
"You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe." - Carl Sagan
"It is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring." - Carl Sagan, The Demon-Haunted World

This message is a reply to:
 Message 27 by DevilsAdvocate, posted 10-31-2009 3:19 PM DevilsAdvocate has not replied

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lyx2no
Member (Idle past 4706 days)
Posts: 1277
From: A vast, undifferentiated plane.
Joined: 02-28-2008


Message 29 of 81 (533528)
10-31-2009 4:12 PM
Reply to: Message 28 by DevilsAdvocate
10-31-2009 3:57 PM


A Box
Any thoughts if this could hypothetically work?
Draw a box around your ship. Everything within that box must have the same average acceleration or it would not long stay within the box. Now, for a second or ten we could accelerate something aft reducing it's immediate G but we'll pay for it in spades when we get to the stern.
Edited by lyx2no, : Style.

It's not the man that knows the most that has the most to say.
Anon

This message is a reply to:
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Taz
Member (Idle past 3282 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 30 of 81 (533636)
11-02-2009 12:51 AM
Reply to: Message 14 by kbertsche
10-30-2009 2:03 PM


Re: fantasy
kbertsche writes:
Transporting -->matter --> at relativistic velocities requires -->energy. --> Transporting matter is the topic of the OP and the thread.
There you go again, trapped in 16th century way of thinking. After all, people from the age of sail never thought using fossil fuel in a certain way in combination of aerodynamics would allow people to travel from Europe to America in a day.
Basically, instead of allowing room for new innovations and discoveries on space-time travel that doesn't require the energy of an entire star, you insist on a closed minded approach that everything other than the standard model of projectile motion through space the way we currently understand physics is a fantasy.

This message is a reply to:
 Message 14 by kbertsche, posted 10-30-2009 2:03 PM kbertsche has replied

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