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Thomas_Anderson
12-15-2008, 09:04 AM
If you had thrusters in space that accelerated you at, say, 9.81 m/s^2, and given there's no atmosphere, so no terminal velocity. What happens when you actually reach 99.9% light speed? The thrusters are still accelerating you, so do you just keep at that speed forever? So, it wouldn't make any difference with the thrusters on than with the thrusters off?

Williebee
12-15-2008, 09:23 AM
So what happens if you try to accelerate to, or past, light speed?

Me? I make oopsie in my shorts.

In other words? I got no clue, sorry.

Kitty Pryde
12-15-2008, 10:00 AM
Okay, I think thrusters could provide constant acceleration at newtonian speeds, but they wouldn't at speeds approaching c. They would provide constant force, which would cause less and less acceleration as you approach c. Once the maximum speed is attained, in a frictionless environment you could maintain that speed without thrust (that's true at any speed, be it slow or close to c), but i think in reality the vacuum of space does provide a teensy amount of friction (um, space dust? gravity from nearby things?). So my best guess is that you would slow down very very slowly with no thrust.

If you want to make an excuse for going faster than light, wikipedia offers the following: http://en.wikipedia.org/wiki/Faster-than-light#Justifications

(c=the speed of light, for those of you playing along at home)

Mac H.
12-15-2008, 03:20 PM
It is just as if your mass increases, the faster you go.

So your thrusters (providing constant force) which were providing acceleration of 'A1' m/s/s at slow speeds are now only providing 'A2' m/s/s of acceleration of at speed 'v' ... where:

A2 = A1 * sqrt(1-v2/c2)

So as 'v' approaches 'c', your acceleration approaches 0.

The model of pretending the mass has increased has fallen out of favour in recent years, but it is an easy way to visualise it.

Mac

dpaterso
12-15-2008, 03:38 PM
You'll continue to accelerate, but in ever-decreasing fractional increments beyond 99.9%. You'll never reach c

Unless you have an onboard fuel synthesizer or the capability of collecting external elements to use as fuel, deceleration could be problematic.

-Derek

Sarpedon
12-15-2008, 08:53 PM
I also think that since time slows down as you approach the speed of light, you won't notice your accelleration decreasing; Your accelleration doesn't decrease relative to you, but only to other people (who are not going so fast).

Palmfrond
12-15-2008, 09:00 PM
You asymptotically approach the speed of light. (Antelope Freeway one half mile. Antelope Freeway one quarter mile. Antelope Freeway one eighth mile. Antelope Freeway one sixteenth mile. etc.)

small axe
12-16-2008, 03:51 AM
I've just always heard the condensed, for-the-layman explanation: as you approach lightspeed, your mass approaches infinite, and so (as stated above already) each acceleration requires more energy to accelerate your increased mass ... Since it would take INFINITE energy to push you over lightspeed, and the Universe doesn't have that much juice ... lightspeed is impossible.

Another explanation I've heard is this: Space/Time is a thing where, you never "move" thru the combined Space/Time faster than the speed of light: If you just sit there with no acceleration in SPACE, all movement is through TIME (our normal time passes)

Any motion you make through SPACE, slows your acceleration through TIME, so that as you approach lightspeed moving in SPACE, you're slowing your motion through TIME: you can never hit lightspeed because (once again) the increments slow you through TIME ... and TIME stops before you can ever be moving at lightspeed.

Can that be right? Why would Time stop for the INSIDE, accelerating relativistic observer?

I grasp that the NON-accelerating observer left behind would seem to experience increased time-passage (the familiar "I traveled in my starship for a year, and 1000 years had passed back on Earth") ... but how is it that the person INSIDE the starship experiences "Time stopping" FOR THEM at lightspeed?

Can someone explain/correct my mis-understanding there? :)

Julie Worth
12-16-2008, 04:46 AM
Can someone explain/correct my mis-understanding there? :)


For a passenger, the interior of the ship would not change. The one G acceleration would still plant her feet on the floor. By the ship's gauges, the fuel use would remain constant. Outside would be a different story, though. Stars in the forward screen would turn blue, then ultraviolet, while those in the rear screens would turn red, then infrared. The galaxy would seem distorted, as though squashed in the direction of travel. Stars would get so close together that you could travel between them in very little time. Go fast enough, and you could cross the galaxy in just a few minutes, ship time. This is due to time dilation, of course. From the POV of someone still at home, a hundred thousand years will have passed.

Travelling at light speed, as photons do, no time passes at all. A photon crosses the universe in an instant by it's own reckoning.

small axe
12-16-2008, 07:26 AM
For a passenger, the interior of the ship would not change. The one G acceleration would still plant her feet on the floor. By the ship's gauges, the fuel use would remain constant. Outside would be a different story, though. Stars in the forward screen would turn blue, then ultraviolet, while those in the rear screens would turn red, then infrared. The galaxy would seem distorted, as though squashed in the direction of travel. Stars would get so close together that you could travel between them in very little time. Go fast enough, and you could cross the galaxy in just a few minutes, ship time. This is due to time dilation, of course. From the POV of someone still at home, a hundred thousand years will have passed.

Travelling at light speed, as photons do, no time passes at all. A photon crosses the universe in an instant by it's own reckoning.

I guess that's what my mind was rebeling against (and perhaps is still unclear to me, from your comments): Would the crew inside the ship experience Time continuing to pass, despite an outside observer thinking "Time has stopped for them, like for the photons" ???

If so ... would the CREW inside live 70 years then die of normal "time passing/old age" (according to the crew) ... but never die according to the outsider who thinks NO TIME can be passing for the crew?

Would it be a sensation of "living forever, but it felt like only 70 years?"
or
"we lived forever in a moment" (In which case, since one action must follow another action, in two different moments ... how's that POSSIBLE?)

Never mind that if the CREW is living FOREVER (even relativistic "forever") ... what happens when the Universe ages and dies around them at the end of Time ... if the crew has escaped Time? :)

I'm ranting. But any insights/advice would be helpful!

eLfwriter
12-16-2008, 07:41 AM
This thread makes my head hurt ... If I'm going at lightspeed, I'm obviously going way too fast, so I'd put myself on autopilot and hope that Otto won't drive me into a meteor, asteroid, other space ship, or small planet.

James M M Baldwin
12-16-2008, 08:09 AM
Our current understanding of physics does not allow for such speeds due to the amount of energy required. Even at light speed, travel to the nearest star would require a massive expenditure or time and energy. Many theories have been proposed for solving the problem. Probably one of the most promising means of traversing vast expanses is the theoretical worm hole. As for your question conserning deseleration; Short distance travel, i.e. star to star, once you reach your 99.9c, your speed should remain constant without the need for additional thrust. But space debree could wreak havoc on your trip.

benbradley
12-16-2008, 08:32 AM
You'll continue to accelerate, but in ever-decreasing fractional increments beyond 99.9%. You'll never reach c

Unless you have an onboard fuel synthesizer or the capability of collecting external elements to use as fuel, deceleration could be problematic.

-Derek
You just keep an eye on the fuel gauge, and hope it's accurate. You have to start slowing down when you've used up half your fuel.

I've just always heard the condensed, for-the-layman explanation: as you approach lightspeed, your mass approaches infinite, and so (as stated above already) each acceleration requires more energy to accelerate your increased mass ... Since it would take INFINITE energy to push you over lightspeed,
Not even OVER lightspeed, it would take infinite energy to get up TO lightspeed.

and the Universe doesn't have that much juice ... lightspeed is impossible.

Another explanation I've heard is this: Space/Time is a thing where, you never "move" thru the combined Space/Time faster than the speed of light: If you just sit there with no acceleration in SPACE, all movement is through TIME (our normal time passes)

Any motion you make through SPACE, slows your acceleration through TIME, so that as you approach lightspeed moving in SPACE, you're slowing your motion through TIME: you can never hit lightspeed because (once again) the increments slow you through TIME ... and TIME stops before you can ever be moving at lightspeed.
That's a weird way to look at it that I've never read before, and looks correct to me except for that last statement. Time only stops AT lightspeed, and mass cannot get TO lightspeed, it can only approach it, so time will slow down (relative to a non-accelerating observer), but not stop.

Time on the ship, as seen by a fixed observer, slows down as the ship approaches lightspeed.

Can that be right? Why would Time stop for the INSIDE, accelerating relativistic observer?

I grasp that the NON-accelerating observer left behind would seem to experience increased time-passage (the familiar "I traveled in my starship for a year, and 1000 years had passed back on Earth") ... but how is it that the person INSIDE the starship experiences "Time stopping" FOR THEM at lightspeed?

Can someone explain/correct my mis-understanding there? :)
The "non-accelerating" observer on Earth sees the speeding ship's clock slowing down (even discounting the fact that the ship may be going away, causing a doppler frequency shift, which is itself NOT a relativistic effect), and the traveler sees a clock on Earth speeding up.

Each observer sees his own clock as always going at 'the right speed'. It's not that "time slows down" on the ship - the "time" on the ship is always "correct" in that frame of reference, just as the time on Earth is always 'correct' for Earth.

Dommo
12-16-2008, 10:43 AM
You couldn't hit the speed of light due to the mass of your ship increasing as you got closer. Newtonian physics are pretty accurate up to about 10% the speed of light, after which all bets are off.

A person on the ship simply experiences time differently. To them, in their frame of reference, time is passing as normal, however to an outside observer time is passing extremely slowly for the people on a ship. In effect, if a ship could get up to like 99% C, it could easily travel hundreds of lightyears inside of the the lifetime of the crew. In effect a spaceship like this is in a way a time machine. It allows for people to travel to the future, simply because they experience time at a different rate than those at a different frame of reference.

benbradley
12-16-2008, 11:10 AM
You couldn't hit the speed of light due to the mass of your ship increasing as you got closer. Newtonian physics are pretty accurate up to about 10% the speed of light, after which all bets are off.
Well, it depends on how accurate you mean by 'pretty accurate.' The planet Mercury doesn't orbit the Sun anywhere near 10 percent of lightspeed, but 100 years ago they were wondering why their predictions of its orbit were ever so slightly off.

Julie Worth
12-16-2008, 05:50 PM
I guess that's what my mind was rebeling against (and perhaps is still unclear to me, from your comments): Would the crew inside the ship experience Time continuing to pass, despite an outside observer thinking "Time has stopped for them, like for the photons" ???

Time passes normally for the people in the ship. Any experiment they can do inside the ship shows no difference at all. It's just the outside world that seems distorted.

At light speed, the outside world reaches a maximum distortion. It seems paper thin, and you cross the universe in an instant. If you could go faster than light speed, you'd go back in time.

dpaterso
12-16-2008, 05:55 PM
If you could go faster than light speed, you'd go back in time.
Your scientific source for this bold statement? :)

-Derek

Julie Worth
12-16-2008, 06:03 PM
Your scientific source for this bold statement? :)

-Derek


Actually, as ship time becomes imaginary if you exceed the speed of light, it's hard to say where you'd end up.

If ship time is T and time on the home planet is t, then (from special relativity) T=t(1-v2/c2).5
So when v>c, you're taking the square root of a negative number.

The problem with going faster than the speed of light is getting over the hump at exactly the speed of light, which requires infinite energy for anything with mass. But what if something is created going faster than c so it doesn't have to cross the hump? Tachyons are theoretical particles that aways travel faster than c, but there's never been any evidence for them.

Sarpedon
12-17-2008, 12:49 AM
Its logical, just not correct. Its just that the flow of time seems to be related to entropy, and theres no reason speed could affect entropy.

Although, who am I to say?

Dommo
12-17-2008, 02:58 AM
By accurate, I mean accurate to the point where it's still useful. Within say a margin of error of like 10-20%.

I definitely wouldn't want to plot a starship course using Newtonian approximation at interstellar distances, but for interplanetary stuff, it's probably good enough.

small axe
12-17-2008, 03:10 AM
Time passes normally for the people in the ship. Any experiment they can do inside the ship shows no difference at all. It's just the outside world that seems distorted.


So (???) the crew inside the lightspeed ship thinks "Time feels (at lightspeed inside the ship) like it is advancing at the normal rate for us" ...

Cause-and-effect remains the same: they flip a coin, one second later it hits the floor, same as on Earth.

But to an outside observer on Earth (if they could see what occurs inside the starship, which I know they cannot) ... to them, Time seems to have stopped when the starship hit lightspeed? So ... do they see the crew as FROZEN in Time, where the coin is frozen in mid-air, never falling? Where there can be NO cause-and-effect because there is never the second moment in which anything can result?

The crew is alive and thinking and watching the coin fall, in the exact same moment that the earth observer sees them as "frozen in Time" unable to process the next thought?

Is it logical to speak of "the same moment of Time" ... even if for one observer it lasts a moment, and for another it lasts an eternity?

Is it "the same moment" but only with different relativistic DURATION?

It "feels" like the same moment and duration to both observers, right?

Is there NOTHING in the Universe we can call "simultaneous" regardless of acceleration of the observer?

Is even the FIRST MOMENT OF TIME, in the Universe, not the first moment of Time EVERYWHERE (where ever Everywhere was, however compact or inflated "there" was?)

:) ???

benbradley
12-17-2008, 04:18 AM
So (???) the crew inside the lightspeed ship thinks "Time feels (at lightspeed inside the ship) like it is advancing at the normal rate for us" ...
Let's take out the singularity (I mean the mathematical one, but perhaps physical, too) that "a mass moving at lightspeed" would cause, and let's say it's moving arbitrarily close to lightspeed, so time flows both on Earth and on the ship, just at greatly different rates. This is an old calculus trick, using infinitesimals instead of zero, so the reciprocal isn't quite infinite.

Even if you had infinite energy, you couldn't get these people in the ship up TO the speed of light in a finite time, because it would take infinite acceleration to do that in a finite amount of time, and you're limited to acceleration of two or three gee's, else the people in the ship get squished flat and die. Not how I want to travel. So let them accellerate for a few years at a little over a gee, and they'll be going at maybe 90 percent or 99 percent of lightspeed.

From Google:

the speed of light = 186 282.397 miles per second

From the (alleged) bumper sticker:

186,202.397 MPH: Not just a good idea, it's the law!

I'm sticking to this point, because your example of a mass (the ship and people in it) going AT THE SPEED OF LIGHT, well, how can I say this, it does not make sense. It's like dividing by zero. There's the high school algebra trick that ends up with 1 = 2, and it all uses "legal" operations, except that early on it sets A=B and then divides by (A-B), hiding (to the uncritical eye) the division by zero.

Cause-and-effect remains the same: they flip a coin, one second later it hits the floor, same as on Earth.
Yes.

But to an outside observer on Earth (if they could see what occurs inside the starship, which I know they cannot) ... to them, Time seems to have stopped when the starship hit lightspeed? So ... do they see the crew as FROZEN in Time, where the coin is frozen in mid-air, never falling? Where there can be NO cause-and-effect because there is never the second moment in which anything can result?

The crew is alive and thinking and watching the coin fall, in the exact same moment that the earth observer sees them as "frozen in Time" unable to process the next thought?
In my modified scenario, someone on Earth may live a whole lifetime as the coin on the ship flips over once. There's still cause and effect. Time goes forward in both places.

Is it logical to speak of "the same moment of Time" ... even if for one observer it lasts a moment, and for another it lasts an eternity?
These other questions depend on the ship going AT THE SPEED OF LIGHT which it won't do.

There ARE interesting questions about "a moment in time" on the ship vs. that on the Earth, mainly because they would be a significant distance from each other, and somoene in one place could not possibly know about something happening in the other "at the same instant" as it happens, due to the delay in the time it takes light to travel from one to the other. But this has nothing to do with time dilation due to acceleration. Here' a "light cone" diagram that demonstrates what I'm saying (it's a short article that mentions a lot of high-fallutin' stuff I'm not familiar with, but at least it's what I'm thinking of):
http://en.wikipedia.org/wiki/Light_cone

Is it "the same moment" but only with different relativistic DURATION?

It "feels" like the same moment and duration to both observers, right?

Is there NOTHING in the Universe we can call "simultaneous" regardless of acceleration of the observer?

Is even the FIRST MOMENT OF TIME, in the Universe, not the first moment of Time EVERYWHERE (where ever Everywhere was, however compact or inflated "there" was?)

:) ???
The Big Bang is yet another deal, and the speculation I've read of was that time and a lot of other things were bit nebulous back then. But since then time (and most of the laws of physics) has settled down pretty well, and we can measure it real good now. For an example, check out how a GPS receiver tells your position by receiving the signals from GPS satellites.

Julie Worth
12-17-2008, 08:22 PM
Your scientific source for this bold statement? :)

-Derek

I’d forgotten about this one:

There was a young lady named Bright,
Whose speed was far faster than light;
She set out one day
In a relative way,
And returned on the previous night.

VeggieChick
12-18-2008, 01:08 AM
OMG. I'm absolutely fascinated by this thread, even though I have no idea what's going on.

small axe
12-18-2008, 09:43 AM
'Little Johnny, just for fun
Played with daddy's photon gun
He pulled the trigger with such elation ...

Now he's cosmic
Radiation'

-- Asimov (I think)

benbradley
12-18-2008, 08:11 PM
Id forgotten about this one:

There was a young lady named Bright,
Whose speed was far faster than light;
She set out one day
In a relative way,
And returned on the previous night.
I can see a new Geraldo report: "When Scientists Write Limmericks"

Guffy
12-19-2008, 03:32 AM
the Large Hadron Collider will accelerate a neutron to near the speed of light and slam it into a mass of atoms. it is hoped that this will answer some unanswered questions. one unanswered question is what makes gravity work. no one knows. another unanswered questions is why a whole bunch of positively charge protons in the nucleus of an atom don't repel each other. Einstein new that his theory of relativity had some holes in it. he even predicted how we could find out where those holes where. if the LHC doesn't create a black hole that destroys the world maybe we'll get some more information on some of Einstein's theories. if one physicist is correct he will prove the existence of parallel universes. cool.

small axe
12-19-2008, 10:49 AM
if one physicist is correct he will prove the existence of parallel universes.


But in another Universe, sadly he will not. ;)

waylander
12-19-2008, 02:33 PM
You also need to remember that anything you collide with while travelling close to c has very significant mass, even space dust. That becomes significant in maintaining the integrity of the craft.

Julie Worth
12-20-2008, 12:20 AM
the Large Hadron Collider will accelerate a neutron to near the speed of light and slam it into a mass of atoms.

Not likely, as neutrons are devilishly hard to accelerate unless you have some protons to grab hold of.

Tburger
12-20-2008, 12:31 AM
Not likely, as neutrons are devilishly hard to accelerate unless you have some protons to grab hold of.


Correct. They will be accelerating protons at near c.

Guffy
12-20-2008, 05:38 AM
sorry, protons are correct, not neutrons.

donroc
12-20-2008, 05:45 AM
Back in the 1950s, I read the two-part story by L. Ron Hubbard, To the Stars , in Astounding Science Fiction. In it, the space travelers had to jump beyond the speed of light because, according to Hubbard, if they reached the speed of light they would be forever frozen in time. At least that is what I remember along with the Astronaut's logo Ad astra per aspera.

Valid science? I do not know, but it seemed plausible among other ideas in the story.

Sarpedon
12-21-2008, 08:19 PM
Yes, I think it is valid science. I recall reading that the reason that light goes for unlimited distance is because there's no time passing for them. Thus a photon will never decay, while the carrier particles for say, the strong force and the weak force only can go a short distance before decaying, because they travel slightly slower than the speed of light. Thats why the strong force and the weak force only work for subatomic distances.

So, if a human flies his ship at light speed, he'd be unable to stop it, because he'd have no time to push the button. Likewise the computer would be useless to do the same.

small axe
12-24-2008, 04:11 AM
'All things fear Time ... but Time fears the Pyramids.'

The Pyramids, of course, being seen as the representation in stone of the rays of sunlight flooding down from the divine sun.

Hence ... Time fears lightspeed. :)


************

And a MERRY CHRISTMAS to you all here!

MelancholyMan
01-16-2009, 02:37 AM
Regarding your original question: if you kept the thrusters on you would continue to approach the speed of light but never reach it. But your mass would continue to increase.

GeorgeK
02-17-2009, 05:48 AM
'Little Johnny, just for fun
Played with daddy's photon gun

Wouldn't that be a flashlight?

A few comments: (sorry that some are fragments)
This thread reminds me of what scientists said in the 1800's about train travel, "If you sit outside the compartment, the wind will peel your flesh off!"

Or a half century or so ago when they proclaimed that breaking the sound barrier was impossible. Or how physics prooved that bumblebees couldn't fly.

Just because science agrees that something is impossible, doesn't make it so. Most of the time it just means we don't know how.


But, to the OP, you can have FTL travel in your stories, just don't try to scientifically justify it. Just have a wizard/egg head do it. All the schmoes say, "But that isn't possible!" and the sergeant says, "Tell that to the interstellar jellyfish when you get into the firefight. Now put on your helmet before we drop you out of the hatch at C3. Don't drop your rifle or you'll never find it, and steer clear of the gas giants. The government doesn't want you igniting them. We want to colonize this system."

Ok seriously, how long did you physicists yell and or laugh in front of the computer after reading that?

small axe
02-17-2009, 12:11 PM
Originally Posted by small axe http://www.absolutewrite.com/forums/images/buttons/viewpost.gif (http://www.absolutewrite.com/forums/showthread.php?p=3078738#post3078738)
'Little Johnny, just for fun
Played with daddy's photon gun



Wouldn't that be a flashlight?


It would be a 'flashlight' ... unless it were a laser gun. :)
Both deal in focused light. "Gun" might be the operative word.

If only both species involved in the tragic first contact episode of Orion 4 (see "History of Galactic Wars" Chapter XVI "Orion 4 -- The Accidental War, or, Don't fire until you see the Whites of Their Eyes. Okay, let me get a flashlight") had been able to differentiate between each other's flashlights and laser guns ... how future history would have been happier indeed!

Lhun
02-19-2009, 01:34 AM
This thread reminds me of what scientists said in the 1800's about train travel, "If you sit outside the compartment, the wind will peel your flesh off!"Not scientists who said that.

Or a half century or so ago when they proclaimed that breaking the sound barrier was impossible.I don't think anyone ever claimed it was scientifically impossible. And afaik noone claimed it was impossible to do engineering wise either.

Or how physics prooved that bumblebees couldn't fly.This is another urban legend. Ridiculing the egg-heads is a common trope in urban legends, but scientists are people too with common sense. Actually, most scientists are not only smarter than joe the plumber but beat him in the common sense department just as easily as on IQ test. I suppose this trope is necessary for joe the plumber to feel better, but seriously, if a couple of dozen of scientists get paid to do nothing but think about a solution to a problem, it's not joe the plumber who will find something they missed. Or tell them about a really "obvious" error they made.

Just because science agrees that something is impossible, doesn't make it so. Most of the time it just means we don't know how.
No, that's when an egineer says it's technically impossible. That means we don't have the technology to do it.
If something is scientifically impossible, it means we understand how it works, and it just can't work that way. It's like heavier than air flight vs. Phlogiston theory. There was a time when it was thought that heavier than air flight was technically impossible. But not scientifically (birds fly). Now we can do it.
And there was a time when phlogiston theory was though of as possible. Now we know how oxidation works and we know phlogiston theory is wrong. Just as Lamarckism is wrong. And the demon possession theory of disease is wrong. And the Zeus smiting people theory of lightning strikes is wrong.

GeorgeK
02-19-2009, 06:59 PM
No, that's when an egineer says it's technically impossible. .

Ok, that's where we disagree, because I consider engineers to be scientists too.

Lyra Jean
02-19-2009, 07:24 PM
You can shoot yourself around the sun and end up back in the 1980's. :D

Lhun
02-19-2009, 07:42 PM
Ok, that's where we disagree, because I consider engineers to be scientists too.While i would not group engineers with scientists (they do very different things in very different ways) my point was something else.
There is a difference between "we cannot do it"/"it is impossible to do it" when said from an engineering standpoint. Which really means "not practical".
And the same statement "we cannot do it" when said from a scientific standpoint. Which really means that it violates some laws of nature.
The first is something where it is quite possible that in future the statement is proven wrong. After all, it really is only a kind of personal opinion. It might be the personal opinion of a whole collective of very competent people, but the point is that they're talking about a practical impossibility, not a theoretical one.
It's like flying to the moon vs. perpetual motion machines of the first kind. Flying to the moon was long though impossible. (ancient kosmonauts were on the fence about beanstalks though) Heck, heavier than air flight was long thought impossible. God gave birds wings to fly and humans legs to walk. But the Wright brothers proved them wrong.
Perpetual motion machines on the other hand will never be created by anyone because they flat out violate the laws of thermodynamics. And if those laws weren't the way they are (or something very, very similar) the universe wouldn't exist as we know it.
If you want another example closer to the thread pick FTL. We know accelerating beyond c is impossible. Period. If it was possible to violate that law atoms couldn't exist. Wormholes on the other hand appear to be theoretical possible, but technically impossible since according to our current knowledge it'd take more than the total energy of the universe to create one of non trivial length and/or size. That's somethig some very clever engineer or scientist might some day figure out how to circumvent. Accelerating past c is not.

small axe
02-20-2009, 08:13 AM
You can shoot yourself around the sun and end up back in the 1980's. :D

I can shoot myself around the temple area of the skull, and end up in 1250 B.C. Minoan Crete.

Pat~
02-20-2009, 08:16 AM
My guess is you'll either disappear or die trying.


(Yeah, I'm not terribly scientifically-minded.)

small axe
02-20-2009, 08:52 AM
On the other hand, if my aim were off by just a fraction, I might wake up in 2010.

And trust me, none of us want to be here in 2010! :) I hear they're planning an episode of ANIMAL APOCALYPSE about 2010.

(By "they" ... I mean the race of intelligent cockroaches that will survive us, and dedicate their bug civilization to re-shooting all the cool homo sapiens TV shows, in the Year 35,002,012 AD )

Safer to stick around and hope the saucers get here in 2009, than make a mistake and wake up in 2010.

2old2pb
02-20-2009, 10:40 PM
Wouldn't it be possible to go at lightspeed if you converted all of the the ship's mass to energy? I have no idea of the mechanics involved. I guess it would be something like Star Trek's transporter but I'd guess there would be devices at both ends of the journey.

I'd been toying with another idea. What if you used a power source to motivate your ship that doesn't care what mass your ship was? Maybe like a mobile black hole? A moving gravity well which your ship is always falling towards never reaching, thus accelerating infinitely.

I guess the big question is does a black hole have mass? I was my understanding it does not, the matter has colapsed into a singularity. A globe of non-existence where only the gravity of the mass is left. If there is no mass I would guess your ship's mass can't pull on it deflecting/decelerating it's course.

GeorgeK
02-21-2009, 12:22 AM
On the other hand, if my aim were off by just a fraction, I might wake up in 2010.

And trust me, none of us want to be here in 2010! :) I hear they're planning an episode of ANIMAL APOCALYPSE about 2010.

(By "they" ... I mean the race of intelligent cockroaches that will survive us, and dedicate their bug civilization to re-shooting all the cool homo sapiens TV shows, in the Year 35,002,012 AD )

Safer to stick around and hope the saucers get here in 2009, than make a mistake and wake up in 2010.

If that happens you can always borrow my time machine. Although, I got it second hand at a physics bake sale, so it is not the most recent version and some of the buttons are missing. It only goes in forward at normal speed

Dommo
02-21-2009, 01:11 AM
A blackhole most definitely has mass. Heck we orbit the galactic blackhole that's parked in the center of the galaxy. If I'm not mistaken I believe it's something on the order of a few billion solar masses.

2old2pb
02-21-2009, 02:23 AM
So if you accelerate a black hole towards C it's mass increases too?

small axe
02-21-2009, 04:38 AM
If that happens you can always borrow my time machine. Although, I got it second hand at a physics bake sale, so it is not the most recent version and some of the buttons are missing. It only goes in forward at normal speed

Well, yes, but even the old models like yours, if you go "forward" but faster than light, it goes temporally backward while still going spatially forward ...

Or at least that's what I think the instruction manual claims. It's in Chinese though, so I cannot be sure. I'm not even sure it's a time machine, actually ... but it sure as hell doesn't make a decent piece of toast! (well, actually, it did make one piece of toast, but it also made a thirty foot crater in the kitchen) :) on the upside, we don't need to let the Yorkie go out for his walks anymore, we just toss him a newspaper and tell him "go crater"

vrabinec
03-23-2009, 08:02 PM
Is there a formula to figure out relative time at .9c? I'm trying to get a specific number of years passing for the crew of a ship relative to approximately 4000 Earth years, and I'm wondering how fast the ship would have to be going in order to cut that to about 40 years, passenger time. I had the ship going at .9c, but from what I'm reading here, I may have to speed the thing up.

Dommo
03-24-2009, 01:13 AM
http://www.1728.com/reltivty.htm

This is a simple calculator, that can atleast allow you to ballpark the amount of time the ship experiences(doesn't take into account acceleration/decel).

Basically at .9c, for every year on the ship, 2.29 pass on earth. If you were to go 99.9% lightspeed you'd get about a 22 years for every year on the ship. For your time range, you'd need to go just about 99.995% light speed. That give you 100 years passing outside of the ship for every year spent in the ship.

vrabinec
03-24-2009, 03:52 AM
Crap, that's faster than I wanted to go. Better have the crew hybernate longer....a lot longer. Oh well.

Dommo
03-24-2009, 09:59 AM
Still from a practical stand point hitting .9c would be pretty useful. Being able to essentially cover 2 lightyears in a given year as experienced by the crew ain't to shabby. Makes any star within 50 lightyears reachable easily in a human lifetime, and makes some of the nearer stars reachable in experienced timeframes comparable to what we used to see with old sailing vessels.