Space travel cannot be fast!

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MeteorWayne

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No, but it is limited to the laws of Physics.

Have you ever heard of spellcheck?
 
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orionrider

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Thinking out of the box is maybe the best (only) solution to the problem, like sending frozen embryos, using traversable ships or whatever. Even quantum teleportation or AI colonization. To me, those proposals are more likely to succeed than FTL starships and antigravity.

The simple laws of physics are part of the fabric of our universe. You can't beat inertia, the inverse square law, the speed of light or the absolute zero.
 
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thnkrx

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To me this seems fairly obvious, but...

Ok...your starship hits even a pebble while zipping along at even 0.3 C, the result is a gargantuan release of energy, which vaporizes the ship and everything aboard.

It would also be real handy to have some way of knowing what is in front of the ship, so that say, if you are entering a region where space debrie is relatively common, you can make a minute course adujustment or three and avoid the worst of it.

So...

You have a 'pathfinder' robot probe say a billion clicks or so in front of your starship. The pathfinder detects something that could be a menace, it sends the signal back to the actual starship. Even with relatavistic effects, the message gets back to the starship with several minutes to spare - time enough to take action. You'll probably loose the pathfinders every so often, so you'd be launching new ones, from the starship, every few months? years?

But that still leaves protecting against a direct hit. Yes, it would be prohibitive, in terms of energy requirements to get up to say 0.3 c, to actually slap enough armor on the starship to be able to withstand a direct hit from a pebble. But...
suppose your armor was completely independant of the starship: a very fine 'mesh' or 'sheet', a couple dozen kilometers across, a couple dozen kilometers in front of the starship. Maybe four or five of them in layers, each layer twenty or thirty clicks from the next one. That way, any stray pebble in the starships path hits one of these screens first. The screen isdestroyed, but the starship is intact. You'd probably have to launch new screens every few...weeks? months? They need not chjeck in at more than a fewhundred kilo's each.
 
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Skyskimmer

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A pathfinder would be unlikely to work due to the speeds. You'd have a serious time lag at those speeds, also spotting small grains would require beaming a light source at them and detecting the reflection. This would mean you'd have to be far in advance of the object to have good detection. Then you would have to steer away from it and hopefully have somewhere safer to be. All of this would fall apart if even a small grain knocked out the pathfinder. Anyhow that's how I'd see it.

With a gel/fluid/rubber/materialx like structure, you'd have a lose enough bonding between the whole mass that if it did get hit the object would simple seer through. You cannot absorb even 1 percent of the impact at those speeds, it would seem to be much easier to take a loss. This isn't the way nasa is use to thinking but is a much better way around obstacles, just as we all take risks everyday on our daily transit to school/work. We don't build 80 ton cars for a safe ride we simply take the chance that bad things may happen for the benefit of the greater good.
 
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thnkrx

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A pathfinder would be unlikely to work due to the speeds. You'd have a serious time lag at those speeds, also spotting small grains would require beaming a light source at them and detecting the reflection. This would mean you'd have to be far in advance of the object to have good detection. Then you would have to steer away from it and hopefully have somewhere safer to be. All of this would fall apart if even a small grain knocked out the pathfinder. Anyhow that's how I'd see it.

That is why the pathfinder would be a good couple of light hours (at least) in front of the starship proper. And yes, you would be replacing pathfinders fairly often.

The issue with even small objects searing through the mesh shield...that would depend on what it was composed of. I would also argue that unless it was fairly substantial, anything hitting said mesh shield would be vaporized even as it seared through, as a result of the energy release of said passage. But you'd probably want at least a couple of these shields in place at any given time. Incidently, for the mesh shield, I was thinking of something metalic, much much less than paper thin, and rotating.
 
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Skyskimmer

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thnkrx":2pm6rvqo said:
A pathfinder would be unlikely to work due to the speeds. You'd have a serious time lag at those speeds, also spotting small grains would require beaming a light source at them and detecting the reflection. This would mean you'd have to be far in advance of the object to have good detection. Then you would have to steer away from it and hopefully have somewhere safer to be. All of this would fall apart if even a small grain knocked out the pathfinder. Anyhow that's how I'd see it.

That is why the pathfinder would be a good couple of light hours (at least) in front of the starship proper. And yes, you would be replacing pathfinders fairly often.

The issue with even small objects searing through the mesh shield...that would depend on what it was composed of. I would also argue that unless it was fairly substantial, anything hitting said mesh shield would be vaporized even as it seared through, as a result of the energy release of said passage. But you'd probably want at least a couple of these shields in place at any given time. Incidently, for the mesh shield, I was thinking of something metalic, much much less than paper thin, and rotating.
This would happen repeadily over many years, I don't see how you could have an endless supply of thinks to absorb impacts.
Perhaps if the ship was many kilometers long, but I'm not sure on the math with that.

Just think would you get in a car without a crumble zone? Would a car last very long if it didn't have rubber tires, would a plane be able to land if it simply put out a huge win break, and instatly stopped.
 
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robnissen

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The problem at relativistic speeds is not pebbles, it is molecules, maybe even atoms. It may be possible within the next few generations to approach .1c. But there are two problems with using that ship to send people/zygotes/robots to AC. First at .1c there would have to be some sort of shield to shield against particles, not pebbles. One proposal has been a large ice shield in front of the ship, that would continue to break from impacts with particles and then be refrozen with liquid water. Maybe that would work, but that would add a tremendous amount of mass to your ship/shield system, which would make it harder to reach .1c. The second problem is how would you SLOW down at the other end? The most promising technology right now to reach .1c is to use a solar sail that would start accelerating using solar wind and then once the ship gets past Jupiter, to use lasers to continue to slowly accelerate the ship until it gets to .1c. But there is currently NO technology, even dreamed of, that could be used to slow the ship from .1c to close to 0c once the ship got to AC. So basically, it would take 40 years to get to AC and then there would be a few days of science while the ship flew through the AC system and out the other side. Good luck getting funding for that, assuming it was even possible.
 
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thnkrx

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The problem at relativistic speeds is not pebbles, it is molecules, maybe even atoms. It may be possible within the next few generations to approach .1c. But there are two problems with using that ship to send people/zygotes/robots to AC. First at .1c there would have to be some sort of shield to shield against particles, not pebbles. One proposal has been a large ice shield in front of the ship, that would continue to break from impacts with particles and then be refrozen with liquid water. Maybe that would work, but that would add a tremendous amount of mass to your ship/shield system, which would make it harder to reach .1c. The second problem is how would you SLOW down at the other end?

For particles of atom or molecue size, or maybe even a bit larger...interstellar bussard ramjet or variation thereof. The ramjet, once 'cruising speed' is achieved, would not provide propulsion, except, maybe for minor course corrections, but there should be enough incoming atom/molecue sized stuff to supply the starships power generation needs. The ramjet could also be used for deceleration.
 
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orionrider

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Any kind of 'pathfinder' or 'advance shield' would vaporize on impact, creating still more debris. The problem is MASS. A few grams of sand or a few grams of loose atoms would release exactly the same energy on impact.
At such speeds, even a diffuse hydrogen cloud would blast the ship.

There is no laser, no radar able to detect microparticles far enough to be useful. Remember that in order to change direction, the ship must counter it's own inertia. A 80kg passenger would instantaneously be pulverized against the bulkheads even by the tiniest course change.

There is no way to clear a path in front of a fast spaceship, to avoid or even to see what lies ahead. :(
 
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thnkrx

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Any kind of 'pathfinder' or 'advance shield' would vaporize on impact, creating still more debris. The problem is MASS. A few grams of sand or a few grams of loose atoms would release exactly the same energy on impact.
At such speeds, even a diffuse hydrogen cloud would blast the ship.

Nope. Given the energy released, the destruction would be total - no debries at all, plus the explosion would be far enough ahead of the starship to where there would be no effects from that, either.

There is no laser, no radar able to detect microparticles far enough to be useful.

With present day technology, that might be the case. However, that statment is likely in serious error when it comes to the technology of a century or two from now.

Remember that in order to change direction, the ship must counter it's own inertia. A 80kg passenger would instantaneously be pulverized against the bulkheads even by the tiniest course change.

Being a tad dramatic are you not. ?
 
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thnkrx

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I ahve to go with short replies, because at the bottom of the screen I can't see what I'm typing.

Anyhow, the 'pathfinder' would be about two light hours in front of the starship proper. Assuming scanning equipment up to the task (a reasonable assumption given at least a century of technological improvement), it should be able to detect everything right down to sand grain size within at least a few dozen klicks of its position almost instantly, and larger objects up to several thousand kilometers off within a few minutes. It continually transmits this data back to the starship proper.

Assuming both pathfinder and starship proper are moving at .5c (to keep the numbers simple), the 'now' info reaches the starship two hours after it was collected, during which period the star ship has moved a light hour closer to where the information was scanned. Allowing for a few minutes delay with the actual scanning process, the starship should still have at least 50 minutes to take action of some sort - including, if necessary the sort of minor course correction that could be made with out pulverizing the crew.

As to atom/molecue sized material, again, if the starship is a bussard ramjet or varient thereof, then use that material for fuel. IT becomes an asset, not a liability.
 
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dryson

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The bitter truth that only exist's in reality of Eistein's Universe. In order to break the light speed barrier science and physics must first get away from allowing the use of the word gravity to be used in a generalized context of meaning that gravity is anything that pulls another body to another.

Chemical attraction is not gravity.

Gravity must be looked at not in an Eisteinian methodology of trying to trap people in the non-sense of generalized and specialized phrases to trap the reader but rather science and physics needs to break away from Einstein and begin to use Newton's Law of For every action there is an equal and opposite reaction as the basis to come to an understanding of what Gravity really is.

Once science and physics understand's what gravity is and how gravity effects each type of atom and molecule and how weight is created due to the interaction of gravity with the particle's of the atom then we can break the light speed barrier.

The reason that the speed of light is not the fastest obtainable velocity is because of blackholes. If lightspeed was the fastest obtainable velocity in the Universe then a blackhole would not have any effect upon a light photon passing by or through a blackhole. But since a light photon cannot escape the pull of a blackhole then the gravity of a blackhole is obviously functioning at a faster than light speed velocity. Because the blackholes gravity is operating at a faster rate of velocity then the interaction between the blackhole's gravity and the mass of the light photon will be occuring at a faster than the speed of light velocity. When this interaction occurs the light photon's mass does not increase as the mass of an atom is the electron's, neutron's and proton's but instead the weight of the light photon is increased. This is because the faster that gravity is propogated and interact's with the light photon which is traveling at the speed of light, the light photon passing through the gravitational wavefront will encounter more gravitational waves at a higher rate of frequency which means that more interaction's of a positive and negative magnetic manner are occuring that increases the weight of the light photon or the pull upon the light photon by the blackhole's gravity.

Everyone is so stuck in the Universe of Einstein because it is easier to prove and has been used to build a political science of thought control from which if deviated from will cause those that have based their realities upon Einstein will be rendered nothing more than history.

This is the bitter truth even in science.

Are you going to continue to drive your Model T Ford when everyone else drives what they drive today?
 
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SpeedFreek

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dryson":8rvthvmo said:
The reason that the speed of light is not the fastest obtainable velocity is because of blackholes. If lightspeed was the fastest obtainable velocity in the Universe then a blackhole would not have any effect upon a light photon passing by or through a blackhole. But since a light photon cannot escape the pull of a blackhole then the gravity of a blackhole is obviously functioning at a faster than light speed velocity. Because the blackholes gravity is operating at a faster rate of velocity then the interaction between the blackhole's gravity and the mass of the light photon will be occuring at a faster than the speed of light velocity. When this interaction occurs the light photon's mass does not increase as the mass of an atom is the electron's, neutron's and proton's but instead the weight of the light photon is increased. This is because the faster that gravity is propogated and interact's with the light photon which is traveling at the speed of light, the light photon passing through the gravitational wavefront will encounter more gravitational waves at a higher rate of frequency which means that more interaction's of a positive and negative magnetic manner are occuring that increases the weight of the light photon or the pull upon the light photon by the blackhole's gravity.

Everyone is so stuck in the Universe of Einstein because it is easier to prove and has been used to build a political science of thought control from which if deviated from will cause those that have based their realities upon Einstein will be rendered nothing more than history.
We are stuck in the universe of Einstein because his alternate explanation to your very large paragraph above is the curvature of space.

dryson":8rvthvmo said:
Are you going to continue to drive your Model T Ford when everyone else drives what they drive today?
Are you going to continue riding your magic carpet?
 
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yevaud

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It seems I only reserve this historic commentary about Physics for this forum, but:

"It's not even wrong."
 
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yevaud

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Been there, Done That, Wayne - did it here for years doncha know. :)

This is probably why I desperately require psychotherapy.
 
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csmyth3025

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dryson":2pbqoenc said:
The bitter truth that only exist's in reality of Eistein's Universe. In order to break the light speed barrier science and physics must first get away from allowing the use of the word gravity to be used in a generalized context of meaning that gravity is anything that pulls another body to another.

Chemical attraction is not gravity...
I'm guessing that by "chemical attraction" you're referring to electromagnetic attraction - which is an area of study from which you would would benefit.

I'm not sure why you feel so adamantly that faster than light travel is possible, but asserting that there's a conspiracy throughout the scientific community to prevent people from knowing that it is possible is not going to convince anyone.

A hundred years ago there were still plenty of scientists who gladly embraced the notion that Newton was right and Einstein was full of baloney. Every experiment and observation made in the last hundred years has shown Einstein to be correct. If you can't accept that then you're going to have to devise an experiment that disproves General and/or Special Relativity.

Your comments about black holes and the speed of light are incoherent nonsense. Try putting them in the form of mathematical equations and you might get someone to pay attention.

I'm sure you're already aware, Dryson, that in this forum you can't just dream up physics in your head, state it as fact, and then hope to convince anyone that the scientific community is conspiring to suppress your ideas.

Chris
 
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robnissen

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The temperature of absolute zero is -12,823 degrees Farenheit.

The maximum speed humans can travel is 3.169827c.

There, now if anyone wants to say that FTL speed is possible (or that the current temperature for absolute 0 is wrong), feel free to do so. If anyone challenges you, now you can truthfully say that you read it in on the Internet. And as everyone KNOWS, if its on the Internet, IT MUST BE TRUE.
 
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flyer456654

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I gotta say we really punish Dryson sometimes. I'm happy to see he continues to come back and give everyone a little bit of enjoyment. Now onto the question about space travel being fast....it absolutely can be. Using the infamous Alcubierre spacetime itself would push aside particles...now this isn't exactly possible right now (maybe in the future). If we are talking about sending off a probe tomorrow...then ABSOLUTELY it has to go relatively slow. If we are talking about sending it off in 100 years, than more research should go into plasma shielding, http://www.space.com/businesstechnology ... 00724.html
a nice little bit of technology found on our home site here. Even space.com sees it as a sheild in later years. With the right frequency...they could probably make it deflect actual objects...maybe not.

Basically, where there is a will there is a way. or maybe this is just the ramblings of a madman?
 
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orionrider

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Given the energy released, the destruction would be total - no debries at all

Unless you use anti-matter to annihilate the target, the result of any impact would be a cloud of plasma, every bit as massive as the original pebble.

It doesn't matter if you hit a 1 gram rock or a 1 gram feather or a 1 gram plasma cloud. The energy released by the impact is exactly the same. :idea:

@ Flyer: thanks for the link :)
Plasma shields would -maybe- work against directed energy beams. ie: electromagnetic radiation. However, they would have no effect on kinetic energy. :(
 
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orionrider

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This post is NOT about FTL or even low relativistic speeds.
I wonder how fast a 'normal', current spacecraft can safely cruise...

If my calculation is correct (yevaud?) the answer is: about 114km/sec :(

Say you build a spacecraft designed to resist the impact of a 100kg supersonic artillery shell.
The energy released on impact is: 360m/s x 360m/s x 100kg / 2 = 6.48 x 10^6 joules

This spacecraft would likely be destroyed by a 1g micrometeorite at only 114 km/sec relative speed:
114000m/s x 114000m/s x 0.001kg / 2 = 6.5 x 10^6 joules

114km/sec is not far from the current speed record. The fastest man-made object was the Helios probe at 70km/sec.
 
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neilsox

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Self repairing machines may be the result of NANO technology, but one thousand years seems unlikely for reliability. Neil
 
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csmyth3025

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neilsox":1nnmjk66 said:
Self repairing machines may be the result of NANO technology, but one thousand years seems unlikely for reliability. Neil
If one were to view cities (or human settlements) as self-repairing machines, there are over a hundred cities worldwide that are reputed to have been continuously inhabited for over 1000 years according to the Wikipedia article here:
http://en.wikipedia.org/wiki/List_of_cities_by_time_of_continuous_habitation.
There is evidence that some of these settlements have been continuously inhabited for 10,000 years or more.

Regardless of the level of technology, humans seem to have the ability to maintain the infrastructure in which they live for very long periods of time. Relying strictly on autonomous robots may not prove to be a long-lasting solution, but a generation ship with lots of people on it is a different matter.

Chris
 
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KhashayarShatti

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orionrider":7l3nkxbx said:
I keep reading posts about spaceships hurtling 'near the speed of light'... :roll:

Let it be clear, anything real fast is impossible. The reason is plain old physics: Ek = 1/2mv²
The kinetic energy of anything moving is proportional to the square of it's velocity.

Example: a single gram of matter hitting a spacecraft at only 0.3c (100,000km/sec) has a potential energy of 5,000,000,000,000 joules. That is the same energy as 130,000 tons hitting the craft at 1,000 kph. :shock:
Space is not empty. When you begin to speak of significant distances, travel time and velocities, hitting something is almost a certainty.

let's deal with it in terms of damage. Agree? In terms of damage a tiny particle at high relative speed can pass thro' the craft causing little damage without transferring its energy to the craft. A tiny hole repaired immediately by the repair mechanism. Now think of a material similar to piezoelectric that contracts absorbing energy and releasing immense electrical energy. Do you think at atomic resonanse we would be able to obtain this material? Please comment. All this is for those who don't want to get into vacuum. I'm sure bright ideas will crop up soon. Obviously under every circumstances sometimes there is little chance to survive(the Archive Universe).
 
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