Faster Than Light! (but not on an MB......)

[bluegoatwoods]

Really, this is about space travel. And there's not much point to it. Other than my urge to explore possibilities. Join me if you'd like.

One heads-up; I'm exploring the possibilities of faster than light travel, but you'll find that we're not gonna get anywhere that's very optimistic about it. It's a shame......but......

To start with, Einstein (or the Theory of Relativity) really did not say that a spacecraft we might build can not get to speeds higher than that of light, relative to its target. Or its source. He merely said that we would not be able to perceive such an object. The difference is important.

In fact it's not only conceivable, and plausible, that there are objects in the Universe moving, relative to each other, at speeds greater than that of light. It's inevitable. Such objects actually must exist. We actually can see evidence of the existence of such objects, for that matter. Choose a random point in the sky. Somewhere near that point you'll be able to find a galaxy that is somewhere in the range of 11 to 12 billion light-years in distance from us. It will also be receding from us at somewhere more than 90% of the speed of light. At the opposite point in the sky you will be able to find another galaxy at similar distance and speed, moving in the opposite direction. There's no escaping the fact that they're receding from each other at somewhere near 2x the speed of light.

(Actually, there is a way of escaping it. But it would involve distortions and flexibility in space-time so severe that such a view would be immensely more complex than the relativistic universe. We could explore such a universe. But be warned; it's going to be difficult and it's not going to make much sense.)

Einstein did not say that these two galaxies can not possibly exist. What he did say is that there is no way for an observer in galaxy A to perceive galaxy B. For all practical purposes they exist, as far as each is concerned, in different universes. Though you'll note that each one does exist in our universe. Though I should say 'frame of reference' instead of 'universe'. Each one is very close to slipping over the edge of our frame of reference, but they're still here. We're very close to slipping over the edge of their frame of reference. Galaxy A has already slipped over the edge of Galaxy Bs frame of reference. And vice-versa. None of the three denies, or disproves, the existence of any of the others. But perceivability does not cover all three. It only makes it partway. (Perceivability would cover all three if none of them were moving faster than light relative to each other. It's the speed that makes the difference.)

There are ways to argue, I'm aware, that I'm wrong, wrong, wrong about that. But, in order to do so, one must include phenomena and interpretations that are even more weird than what I've just described. I can even argue against my argument above. But the larger universe becomes even more strange in those arguments. We could, in fact, find infinite places to disagree merely by picking and choosing among the infinite frames of reference available to us.

But we really, really can, in theory, build a spacecraft that could be accelerated to some multiple of the speed of light, from the perspective of some target. Though that wording is sloppy since they won't be able to perceive each other. Until they smack into each other. I don't know what'll happen then. It might be worth exploring. But I honestly don't know how. But I do feel confident in suggesting that we'd all best "Stand back!"

(We needn't worry, by the way, that some superluminal object might smack us. It's in the very nature of universal expansion that all of these superluminal relative velocities are in the 'separating', as opposed to 'converging' direction. All bets are off, though, if some hostile aliens start firing faster-than-light missiles at us.)

But there's all sorts of reasons that it's not quite that simple.

For one thing there are very good reasons to think that the practical limit will be well below. One of them is that inter-stellar space is anything but empty. If we were to go out there and try to breathe, we'd consider it to be a very good vacuum. But there's still plenty of matter there. From hydrogen atoms to Alpha particles (helium nuclei) right up through some surprisingly complex organic chemical compounds. Again, they would seem to our senses to be a pretty thin soup. But they're thick enough to be detectable on Earth by their effect on light that passes through. This is thick enough to make fast travel somewhat tricky.

If a spacecraft traveling somewhere near the speed of light strikes a hydrogen atom or an Alpha particle the effect is identical to the hydrogen atom, at near-light speed, smacking into a stationary spacecraft. This is a cosmic ray.

Being hit by one cosmic ray is not a big deal. But being hit by a bunch of them can be dangerous. And the cosmologists seem pretty certain that the amount of matter in inter-stellar space is enough that a spacecraft moving through at some appreciable fraction of the speed of light is going to be bathed in all sorts of hard radiation. Enough to fry it.

We might consider shielding our spacecraft with something stout. Like lead armor. But this brings us face to face with another difficulty. If we imagine accelerating a spacecraft to near light speed, or above, we must imagine using up some pretty huge quantities of fuel. Probably enough to make the prospect not practical. If you start making the spacecraft even heavier, then this problem multiplies. It shouldn't be too hard to calculate how much of today's rocket fuel would be needed to accelerate some spacecraft of today to such velocities. I've never tried. But I'm willing to bet that the answer, even for an un-armored spacecraft, would turn out to be enormous.

So while relativity actually does not forbid our hurling a spacecraft out of here at huge speeds, practical considerations almost certainly forbid us. At least inside our galaxy. On the hard radiation issue, I've seen estimates that 10% of the speed of light might be reaching the safety limit.

So we might wonder if it's possible to travel at superluminal velocities in inter-galactic space. I suspect that hard radiation might not be a huge problem out there. The trouble, though, is that getting from Earth to some point outside the galaxy, where it's safe to hit the throttle, might take a half a million years. There doesn't seem to be much point in exploring possibilities like this.

If the Theory of Relativity does not forbid us from traveling faster than light, the practical issues seem pretty close to doing so. They seem to be preventing us even from getting beyond 10% of that speed.

It's hard to say that anything is truly impossible. But it would appear that inter-galactic travel is nearly impossible. Using Newtonian physics, anyway. Maybe a trip to the Andromeda galaxy is just barely conceivable. But if it's going to take four million years, then it wouldn't seem to be feasible. Can you imagine a spacecraft actually working for that long?

How about travel within our own galaxy? Or just within our own little corner of the galaxy? Well, that 10% percent speed limit will make things difficult. A trip to the very nearest star would take 40 years. Possible, yes. But I doubt if anyone will make a serious attempt anytime soon.

We could hope for non-Newtonian methods. The 20th century science fiction writers, in fact, had to assume non-Newtonian methods of getting around. Isaac Asimov made use of 'hyper-space'. Robert A Heinlein did the same thing. Only he made it less precise and more difficult. But those guys were merely acknowledging the fact that action/reaction propulsion was not adequate. If you could ask them "How?", they wouldn't have an answer. They assumed that somehow humanity would find some method of making a spacecraft 'wink' out of existence at one point in the universe and 'wink' into existence at another. And they simply ignored the fact that Newtonian travel from the wink point to the eventual target would likely be too slow to be useful. They had to do this. Otherwise their stories wouldn't work. But they didn't have the answer. Only a couple of convenient fictions. They knew this perfectly well, by the way. They weren't trying to hoodwink anyone. They were only trying to write stories.


Yow! I'm so longwinded that I've actually run into the word limit for one of these posts.

So I'll have to do a part two.

 

[bluegoatwoods]

Some folks still hope to find natural non-Newtonian methods. They hope that 'wormholes' in space might exist. That you enter a wormhole at some point in space and exit at another. Some hope that black holes might accomplish the same thing. But it's hard to see how a spacecraft, and the people inside, could enter or leave a black hole without being torn to bits. Tidal forces beyond our imagination are inevitable. Maybe a wormhole, whatever it might be, won't have intense gravitational fields associated with it, though. So maybe we can imagine a galactic map with wormhole entries and exits plus human habitation near these entry points. But that Newtonian 10% speed limit means that these human habitations can't be very far from these entry points. If the nearest one to Earth is more than, say, 1 light-year away (very likely), then it's pretty safe to assume that we'll never get out that far to find it.

We can hope for some sort of breakthrough. But it's only a hope. More in the realm of fantasy than realism.

For the moment, it would seem that the human race is really confined to the Solar System. This isn't all bad because our solar system is quite a big place, after all. It's not nearly as hospitable as those writers mentioned above pictured it to be before the actual space age. We've lost so much of what they'd hoped for. Mercury was envisioned as keeping one face toward the Sun at all times. (The way the Moon keeps one face toward Earth) The sunside would have been the hottest matter in the Solar System. Aside from the Sun itself. The darkside would have been about the coldest. But the twilight zone would have been at a reasonable temperature. As habitable as the Moon, anyway, without the Moon's temperature swings. But it turns out that Mercury actually does rotate with respect to the Sun. Nice and slow, too. With the result that every square inch of it is roasted as if on a rotisserie. It might not be quite impossible for human beings to set up shop there. They'd need to land at some point where the Sun has been down long enough that the ground is cool enough to touch. Then they'd need to start digging, fast and deep, and get underground before the Sun came up again. Do-able, I suppose. But I doubt if anyone is going to do it without some compelling reason. It would have to be really compelling, too, to go to that kind of trouble. And danger. A slip in the construction schedule means they're getting out of there now or they're getting roasted.

Venus and Mars were thought, or hoped at least, to be so Earth-like that living there wouldn't even be much like what we think of as living on another planet. But Venus, it turns out, is so hostile that there's little hope that human beings even could land there. And in what kind of ship? It's hard to see it happening. Mars was largely believed to have plant life before Mariner 4. (Though maybe not by those who were really in-the-know.) Now it's known to be, maybe, a bit less hostile than the Moon on average. But it's not very inviting.

The Galilean satellites of Jupiter had high hopes. But then it was discovered that Jupiter's magnetic field is so intense that hard radiation (from Solar wind entrapment) is so intense there that, once again, humans might not dare to enter. If it's possible at all, then it's at least going to be much harder than had been hoped.

I've heard nothing, it's true, to make it seem as though the satellites of Saturn, Uranus or Neptune are unapproachable. Other than the fact that if we have no stepping stones in between us and them, then it becomes questionable whether or not we'll ever actually send people out that far.

But there's still the asteroids. And they do hold promise. I once read an essay that imagined an asteroid with a diameter of 50 miles. Not an uncommon size, I believe. This asteroid was imagined to be bored, or honey-combed, into a series of tunnels, or decks, with people living on the inside. The author calculated the usable living space on the inside to be comparable to one of our large continents like Africa or Asia. Now this is impressive.

There are a lot of asteroids to be used in this fashion. And I believe they contain not only metals and silicates and carbon, but also the volatiles. Water, hydrogen, etc. When boring out living space in these asteroids a lot of usable material would be produced. Though I imagine containing it until use might be a bit of a problem. It's not hard to imagine the engineers, figuratively, letting this stuff slip through their fingers with a sigh. Wishing they could save it for future use, but knowing of no economical way of doing so.

If those chemical elements needed for physiology and for maintaining a technology are to be found there, which seems likely, and are added to the plentiful solar energy to be found, then it would seem likely that living space for several times Earth's current population could be engineered out there without any ridiculous advances in technology beyond that of today. Bore it out, seal up the ends, crack oxygen out of the silicates using solar energy and you've got a livable space with an atmosphere. There's more to it than that, of course. Making the soil fertile, for instance. Okay, that means importing bacteria, and more complex scavengers and such, from Earth. Getting it truly habitable might not be really simple. And it would likely take years, more likely decades. But it wouldn't seem to be beyond possibility.

Such an asteroid colony would actually be pretty isolated. They're not all that close together. It might take a year to travel from one to another. Aside, perhaps, from the very nearest to each other. This isn't necessarily a bad thing. But they would be the equivalent of sovereign nations, I suppose. Even electronic communication with Earth or with other asteroid colonies would not be instantaneous. And it seems hard to imagine any advantage to having trade between them if they all have the same raw materials. Though they surely could specialize and trade. I'm just not sure I see any strong reason to do so.

But a similar colony could be established among the outer satellites of Jupiter (further than the large moons and outside of that dangerous radiation) or of the outer planets. These could probably be colonies with several times the living area and the population of Earth which are, nonetheless, one political and cultural unit.

And consider one advantage they'd have over us. They wouldn't have to use up horrific amounts of fuel lifting material out of this deep, deep gravity well that we're living with. Though a colony in the outer-Jovian system might have to fight some pretty strong gravity. Jupiter's gravitational field is strong and they won't be very far away.

Colonize the asteroids and I can easily envision a time when the human race considers a planetary surface to be unfit for human habitation.

And what if we do, in the end, end up poisoning or polluting or otherwise ruining this Earth? Or what about a natural disaster like a large asteroid strike? There'll be other places to live! They'll be immune to whatever happened here. In fact, it's hard to imagine any threat that could bring all of them to extinction. Short of the natural death of the Sun. And that's about 5 billion years away.

Imagine our descendants 5 billion years from now. We might not even recognize them as human. But that would be no reason for enmity, provided they're humane. And, besides, there's no conceivable way for our descendents that far in the future to 'look' like us. Though I'm not talking about physical characteristics only.

But if they can last, with a thriving technology, until the death of the Sun, then maybe they'll have reached the point that they can go to other stars. 5 billion years is a very long time, after all. Heck, our descendents might be several different species by that time. Probably. And probably more than just 'several'. All of them spreading out and colonizing new solar systems until the natural death of the Universe. They might get far.

Now there's an accomplishment that the human race could take some pride in. Sowing the seeds would seem like something that is conceivable with technology that exists today plus some improvements that wouldn't seem to be so far away.

Colonizing the Solar System shouldn't be all that hard. And I sure can see some big possible payoffs. We ought to go for it.

 

[2door]

"Warp factor five, Mr. Sulu. And step on it"

Gene Rodenberry found a way to exceed the speed of light. Why couldn't we?

Also, as far a building a vehicle with enough fuel...weight wouldn't be a factor in space.
And remember, "In space, no one can hear you scream"

Just having fun with your theories, Goat. No offense.
Interesting reading. Thanks.

Tom

 

[bluegoatwoods]

Also in space no one can hear me sing! My wife tells me that you'll all be grateful for that.

She also told me to stay away from the Star Trek stuff. Being somewhat warped already, I'm not able to be objective.

 

[2door]

Also in space no one can hear me sing! My wife tells me that you'll all be grateful for that.

She also told me to stay away from the Star Trek stuff. Being somewhat warped already, I'm not able to be objective.

I prefer the shower to do my singing. That echo effect hides the faults and personally, I think I sound pretty darn good in the shower. Somewhere between Frank Sinatra and Garth Brooks.

Tom

 

[bluegoatwoods]

Frank Who? Garth Who?.....Sorry, man....I'm not into that classical stuff.

I've been told that I sound something like Leo Sayer. Being tased.

 

[maniac57]

While it's true you have no weight in space, mass and inertia still apply leaving the same problems with fuel vs range/speed/duration of thrust.
Current thinking seems to favor small acceleration over a long time to build speed rather than massive power. Once you're out of Earth's gravity it gets a bit better but the problems do not go away with the gravity.
The Bussard Ram has the same issues you mentioned even if the collector is assumed to act as a shield...getting to any real useful fraction of c (speed of light) means radiation becomes the issue.
I once read somewhere that to protect a human at 50% of c would require something like four MILES of lead! Good luck accelerating THAT.
Wormholes and hyperspace may be fiction, but unless we somehow get around these issues with something like them, we're pretty much trapped in this system for the forseeable future.

 

[bluegoatwoods]

Yes. I'm no expert here, but I think the reason that low acceleration is favored is simply that it's impossible to imagine a reasonable way of fueling high accelerations.

Imagine the old Saturn V third stage. The engine that propelled the Apollo spacecraft from Earth orbit into it's path to the Moon. That engine did all of it's work in a handful of minutes. And it used up all of its fuel doing that. I think it used part of its fuel, actually, helping the craft to attain Earth orbit also. But the principle is the same; such a huge tank (larger than the spacecraft) using up it's fuel very quickly. In my post I toyed a bit with the idea of something similar burning for, say, a month. To get up to very high speed. But that was just playing with theoretical possibilities. Fueling such a thing would be practically impossible.

Ion drives and such, while very low thrust, are actually able to operate for long periods of time. Very long compared to chemical fuels. So they are our best bet by default.

But it does look as though moving at really high speeds is dangerous enough that the danger is a bigger problem than the fueling.

 

[xseler]

This may just be the thoughts of a warped mind, but, the only way I can fathom traveling faster than light is to travel within a beam of light......similiar to the way aircraft can travel faster by utilizing the jet stream.

 

[bluegoatwoods]

I guess I see what you're getting at, xseler. You're being 'carried' by a beam of light. If you could, somehow, 'swim' with it then your total speed would be c + (your speed relative to the light beam). Something greater than 'c', certainly.

I suppose one effect would be your red-shifting this beam of light. But that wouldn't affect your speed.

I'm guessing, though, that finding a way of being pushed by a beam of light might be every bit as difficult as finding a way to travel through hyper-space or to invent an inertialess drive.

It gets worse, too. Merely achieving the speed of light, or a bit more, isn't gonna be enough. To even begin to explore any reasonable portion of our own galaxy will require speeds in the neighborhood of 1000 x c at least.

It just gets harder and harder.

 

[xseler]

I can go anywhere I want in a blink of an eye ---- it's called "Imagination Drive".....patent pending.

 

[Ludwig II]

I don't even have to blink an eye, I just shift a couple of chemicals around.

No, not those.

 

[gaffo]

Really, this is about space travel. And there's not much point to it. Other than my urge to explore possibilities. Join me if you'd like..

thanks I shall, love space stuff.
............will reply in parts if need be - due to this sights terrible "timing out, and loosing whole posts" problems - been there done with that - thanks.

To start with, Einstein (or the Theory of Relativity) really did not say that a spacecraft we might build can not get to speeds higher than that of light, relative to its target. Or its source. He merely said that we would not be able to perceive such an object. The difference is important..

I disagree - you state the difference, but its not important, because your first assertion is wrong. No object can travel THROUGH space at faster than light speed. Space itself can travel faster than light (and it does inside of Black Hole Event Horizons) and objects in that space might be able to - but only because they are "carried" by space and not traveling through it.

In fact it's not only conceivable, and plausible, that there are objects in the Universe moving, relative to each other, at speeds greater than that of light. It's inevitable. Such objects actually must exist. .

We its believed that there is a Universe Event Horizion (due to the acceleration of the Red Shift) - so relative to us there is an observable edge to space in all four directions and objects (galaxies) in those 4 directions relative to us are all traveling at lightspeed (and so the galaxies at the two opposite UEHs are traveling at 2x speed of light relative to each other (and we are traveling at lightspeed relative to both of them). They cannot see each other and so don't even know the other exists however - since they are off each other's Obveravable Universe Event Horizon.

---and its the space that is expanding - not objects traveling though that space.

 

[Ludwig II]

This is plainly demonstrable; as time has gone by, many of us have also expanded.

 

[gaffo]

Choose a random point in the sky. Somewhere near that point you'll be able to find a galaxy that is somewhere in the range of 11 to 12 billion light-years in distance from us. It will also be receding from us at somewhere more than 90% of the speed of light. At the opposite point in the sky you will be able to find another galaxy at similar distance and speed, moving in the opposite direction. There's no escaping the fact that they're receding from each other at somewhere near 2x the speed of light.

(Actually, there is a way of escaping it. But it would involve distortions and flexibility in space-time so severe that such a view would be immensely more complex than the relativistic universe. We could explore such a universe. But be warned; it's going to be difficult and it's not going to make much sense.)

Einstein did not say that these two galaxies can not possibly exist. What he did say is that there is no way for an observer in galaxy A to perceive galaxy B. For all practical purposes they exist, as far as each is concerned, in different universes. Though you'll note that each one does exist in our universe. Though I should say 'frame of reference' instead of 'universe'. Each one is very close to slipping over the edge of our frame of reference, but they're still here. We're very close to slipping over the edge of their frame of reference. Galaxy A has already slipped over the edge of Galaxy Bs frame of reference. And vice-versa. None of the three denies, or disproves, the existence of any of the others. But perceivability does not cover all three. It only makes it partway. (Perceivability would cover all three if none of them were moving faster than light relative to each other. It's the speed that makes the difference.)

presicely - I had not read this far above - now I see there was not need to post above what you also said above.


as for space not being empty - there are three "spaces" to space.

Interplanetary (solar and ex-solar system "space" - which has something like 1 atom (H/He) per cm3

Interstaller "space" 1 atom per cubic meter

and Intergalactic "space" 1 atom per km3?

and there is even "spaceyer space" - huge areas of "Galactic Voids" - 100 million yr space volumes where there is even less atoms per volume.


not only does kenetic energy release of a small spec of dust ensure complete obliteration of a colony ship traveling at 90-pecent light speed, the power input to get to 91-percent is not linear - but square (or more?) so that there come a point where there is not enough power to be found to go any faster.


..............

also current theory is that the Observable Universe makes up 3-percent of THE Universe - 97-percent of it is outside of the Observable Universe Event Horizon.

a good podcast is Astronomy Cast (one show talked about this 6 yr ago or so) titanium Phycists is another good podcast.

try google to find them.

 

[gaffo]

How about travel within our own galaxy? Or just within our own little corner of the galaxy? Well, that 10% percent speed limit will make things difficult. A trip to the very nearest star would take 40 years. Possible, yes. But I doubt if anyone will make a serious attempt anytime soon.
.

I think "aliens" have a similar view - and why they are not here (or anywhere else - other than on their own planet). the distances are just too far, to make travel worth it.

If Sun was size of a marble the closest star to us (A Centauri (tech I think red dwarf Proxima is closest)) would be sixty miles away.

We could hope for non-Newtonian methods. The 20th century science fiction writers, in fact, had to assume non-Newtonian methods of getting around. Isaac Asimov made use of 'hyper-space'. Robert A Heinlein did the same thing. Only he made it less precise and more difficult. But those guys were merely acknowledging the fact that action/reaction propulsion was not adequate. .

Haldeman in his Forever War liked to use Black Holes (as did Niven in his short stories), including their Time Dialation effects (little-no aging for the traveler - much aging for the colonialists).

 

[gaffo]

Some folks still hope to find natural non-Newtonian methods. They hope that 'wormholes' in space might exist. That you enter a wormhole at some point in space and exit at another. Some hope that black holes might accomplish the same thing. But it's hard to see how a spacecraft, and the people inside, could enter or leave a black hole without being torn to bits. Tidal forces beyond our imagination are inevitable. .

true - "spegetification"..huge HB have a lower tibal force though. we could go inside the one at the center of our galaxy without being torn apart.

but that thing has been literally swallowing entire Suns for 10 billion yrs now and all the gas and heat of all those Suns has not been able to transfur to the outside - so all that heat of 3 billion suns are still as hot as the day they fell into the BH - just waiting to babique your arse the second you slip inside the event horizon.

"we made"............. (it)!!!!!!!! said the Captain. ;-).

.............

the "Thing" at the "Center" (Singularity) would still kill you within the couple of hours it take you to reach it anyway (assuming you were not burned up from the 3-billion trapped suns - which you would be).

 

[gaffo]

Venus and Mars were thought, or hoped at least, to be so Earth-like .

Venus SHOULD be (but isn't) another Earth - she is our size and SHOULD have a Magnetic Field to protect her (but doesn't), and is TWICE as close to us than Mars.

Mars was just a tad too small and lost her Magnetic Field 3.8 billion yrs ago. (within the first billion yrs (or less even)). She is 1/10 that of Earth/Venus.

Had she only been say 1/5th or so Earth's size she could be a decent place today (other things willing - like atmosphere/etc...)

..........

Venus really really should be a nice 80-degrees at the Poles dammit.

should have a mag field too dammit. she's a big girl.

a lot bigger than mercury, whom does have a mag field!

-none of it makes sense.

 

[gaffo]

And what if we do, in the end, end up poisoning or polluting or otherwise ruining this Earth? Or what about a natural disaster like a large asteroid strike? There'll be other places to live! They'll be immune to whatever happened here. In fact, it's hard to imagine any threat that could bring all of them to extinction. Short of the natural death of the Sun. And that's about 5 billion years away.

Imagine our descendants 5 billion years from now. We might not even recognize them as human..

"Man" will no longer be "man" in a much shorter time than 5 BILLION YRS!!!!!!!!!!! He'll be "not man" (or exict) within 50,000 yrs at most - 1000 with genetic engineering.

by the time the Sun kills life on Earth - 1 or 2-billion yrs (not 5) (sun is getting hotter 10 percent per billion yrs) there will have been 30 or 40 "cycles of "man" (i.e. some sentient animal from mindless beast ancestors)

assuming natural 20 million evolutionary cycle -self exiction - rebuild - self extinction - re-build (all from different animal ancestors).etc 30 times until Sum bakes the Earth.

 

[Ludwig II]

I ask if the Moon orbiting is the motor for magnetism here,=; Venus has no moon, and Phobos & Deimos are but stray rocks that orbit Mars.