Traveling at the speed of light

[TransformerRobot]

Okay, if wormholes are only theoretical, and it's too difficult to estimate when we'll have the technology to acheive light speed, all I can think of now is making ships that can exceed speeds of 100,000 miles per hour, because that seems more believable now than traveling at the speed of light.

[ACG52]

Okay, if wormholes are only theoretical, and it's too difficult to estimate when we'll have the technology to acheive light speed, all I can think of now is making ships that can exceed speeds of 100,000 miles per hour, because that seems more believable now than traveling at the speed of light.

 

 

Well, at 100,000 miles per hour, it will take 28767 years to reach the closest star. I can't wait that long.

[TransformerRobot]

Well, at 100,000 miles per hour, it will take 28767 years to reach the closest star. I can't wait that long.

 

Well I didn't think it would be safe for the ship to go something like 10,000,000 miles per hour. At that speed it would be at risk of hitting an asteroid or comet.

[insane_alien]

Well I didn't think it would be safe for the ship to go something like 10,000,000 miles per hour. At that speed it would be at risk of hitting an asteroid or comet.

 

no more at risk than if it was going at 10000mph.

 

large objects are (counter-intuitively) not the largest hazard. they can be easily seen and a small burst from the attitude control thrusters(or manouvering thrusters) would be sufficient to avoid them.

 

The big problems with near luminal travel come from dust. you won't see the dust and if you go fast enough each grain will be as destructive as a hiroshima bomb. of course, if you've managed to get the technology to get up to those speeds then you're likely going to be able to have a lser or something to nudge them out of your way.

[TransformerRobot]

no more at risk than if it was going at 10000mph.

 

large objects are (counter-intuitively) not the largest hazard. they can be easily seen and a small burst from the attitude control thrusters(or manouvering thrusters) would be sufficient to avoid them.

 

The big problems with near luminal travel come from dust. you won't see the dust and if you go fast enough each grain will be as destructive as a hiroshima bomb. of course, if you've managed to get the technology to get up to those speeds then you're likely going to be able to have a lser or something to nudge them out of your way.

 

Would it help to create a magnetic field around the ship to repel the dust?

[ACG52]

Would it help to create a magnetic field around the ship to repel the dust?

 

 

This would only work for electrically charged particles.

[TransformerRobot]

Okay, I'm officially out of ideas.

 

One of the protagonists in my web series is an alien from a far away world, outside the Solar System. It's set in 2135 in case you forgot, so what's the fastest way for her to possibly get to Earth from her planet?

[InigoMontoya]

Okay, I'm officially out of ideas.

 

One of the protagonists in my web series is an alien from a far away world, outside the Solar System. It's set in 2135 in case you forgot, so what's the fastest way for her to possibly get to Earth from her planet?

 

There is no fast way without resorting to Dilithium Crystals or other story-telling magic wand. Using our current knowledge of physics, anyway you cut it, it would take hundreds if not thousands of years to make such a trip. That leaves you with a few options....

 

1) The alien was in some sort of suspended animation for the trip.

 

2) The alien lives a VERY long time.

 

3) The alien is actually the offspring of those who began the trip and was born somewhere along the way.

 

4) Some combination of the above.

Edited May 23, 2012 by InigoMontoya

[Spyman]

Okay, I'm officially out of ideas.

 

One of the protagonists in my web series is an alien from a far away world, outside the Solar System. It's set in 2135 in case you forgot, so what's the fastest way for her to possibly get to Earth from her planet?

If you are writing a science fiction and not a scientific paper or trying to draw a blueprint with the intention to actually build such a travel device, then I don't think you have to worry to much about current scientific knowledge. There are plenty of successful science fictions where they are able to travel faster than the speed of light despite it is currently thought to be impossible to do so.

 

You already have an alien visiting us from a far away world, of course that would be impossible unless they have access to more advanced technology than what we currently have. The only true limit for an fictional advanced alien technology is your own imagination. The aliens could have knowledge that we do not yet possess which supersedes ours and possibly even goes against what we currently knows.

 

Depending on how you want your story they could have invented an expensive proccess to manufacture unobtainium, exotic matter or whatever strange material you like to use in their stargate to open a wormhole or some other kind of portal through space, alternatively if you want them to travel in spaceships the material could be used to craft the core in their engines or simply used as fuel which allows the jumpships to enter hyperspace or to power their warpdrive to superluminal speeds.

 

My advice would be to make your own 'theory' similar to how people are used to view it in movies because then they will have it easier to accept it, so watch some Sci-Fi movies and choose how you want the travel to be performed and read up on the ideas behind in the movies and other similar ways.

 

This Wikipedia article has a list of several well known sci-fi stories and their made up technologies to travel faster than light:

 

Hyperspace is a method of traveling sometimes used in science fiction. It is typically described as an alternative region of space co-existing with our own universe which may be entered using an energy field or other device. Travel in hyperspace is frequently depicted as faster-than-light travel in normal space.

 

Astronomical distances and the impossibility of faster-than-light travel pose a challenge to most science-fiction authors. They can be dealt with in several ways: accept them as such (hibernation, slow boats, generation ships), find a way to move faster than light (warp drive), "fold" space to achieve instantaneous translation (e.g. the Dune universe's Holtzman effect), access some sort of shortcut (wormholes), or sidestep the problem in an alternate space: hyperspace.

 

Hyperspace is sometimes used to enable and explain faster than light (FTL) travel in science fiction stories where FTL is necessary for interstellar travel or intergalactic travel. Spacecraft able to use hyperspace for FTL travel are sometimes said to have a hyperdrive.

 

Detailed descriptions of the mechanisms of hyperspace travel are often provided in stories using the plot device, sometimes incorporating some actual physics such as relativity or string theory in order to create the illusion of a seemingly plausible explanation. Hyperspace travel is nevertheless a fictional technology.

http://en.wikipedia.org/wiki/Hyperspace_(science_fiction)

Edited May 23, 2012 by Spyman

[TransformerRobot]

Well, the alien race I just mentioned is older than mankind by 10,000 years, maybe even more, so I think it would make the most sense to say that they have figured out the technology and science to travel longer distances in shorter amounts of time than us.

[imatfaal]

I like Frank Herbert's method - hide the lack of any scientific rationale behind a mystical priestlike sect who control (and have done for many generations) the ability to move quickly across space. You can even hint that the sect themselves do not fully understand the principles - which is why they so jealously hide the small nuggets of knowledge they do have.

 

Alternatively - I read last night (Kip Thorne) that David Hilbert actually solved the mathematical formalism puzzle regarding General Relativity a few days before Einstein. He had invited Einstein to Gottingen to give a series of lectures on his ideas - (before the maths was consistent) - and was able to put together the Einstein field equations because of those lectures. Invent some lost papers describing a follow-up set of discussions between the centuries greatest minds in physics and maths - the papers can lie lost in Gottingen for several hundred years before being discovered and laying the ground work for ftl travel.

[zapatos]

In the movie 'Contact', the aliens who contacted earth used a mechanism to travel through wormholes. When asked how they did it, they stated that the mechanism existed long before they came along, had been in use for millions of years, but no one knew who created it in the first place.

[michel123456]

The only thing you have to do is to accelerate constantly.

With an acceleration of 1m/s2, it will take you about 9,5 years to reach SOL (If I calculated correctly). At g (9,8 m/s2) it will take about one year.

[InigoMontoya]

The only thing you have to do is to accelerate constantly.

With an acceleration of 1m/s2, it will take you about 9,5 years to reach SOL (If I calculated correctly). At g (9,8 m/s2) it will take about one year.

 

You didn't.

 

Newtonian physics break down at relativistic speeds.

Edited May 24, 2012 by InigoMontoya

[TransformerRobot]

You didn't.

 

Newtonian physics break down at relativistic speeds.

 

Then let's see your calculations.

[InigoMontoya]

I fully confess that I've not had to do such calcs in 20 years and am no longer up on the math required beyond remembering it involves the Lorentz Transform. However, a quick google for "acceleration at relativistic speeds" gives me a wikipedia link to time dilation...

 

Time dilation at constant acceleration

 

In special relativity, time dilation is most simply described in circumstances where relative velocity is unchanging. Nevertheless, the Lorentz equations allow one to calculate proper time and movement in space for the simple case of a spaceship whose acceleration, relative to some referent object in uniform (i.e. constant velocity) motion, equals g throughout the period of measurement.

Let t be the time in an inertial frame subsequently called the rest frame. Let x be a spatial coordinate, and let the direction of the constant acceleration as well as the spaceship's velocity (relative to the rest frame) be parallel to the x-axis. Assuming the spaceship's position at time t = 0 being x = 0 and the velocity being v0 and defining the following abbreviation

the following formulas hold:[17]

Position:

Velocity:

Proper time:

 

In the case where v(0) = v0 = 0 and τ(0) = τ0 = 0 the integral can be expressed as a logarithmic function or, equivalently, as an inverse hyperbolic function:

 

 

A fun little numbers excercise I *can* still do, however.... And mind you, I'm going to neglect relativistic effects here. While I know the real version of what I'm about to say is much, much worse, this should be an interesting exercise....

 

Suppose you want to get your spaceship to 0.5c on the way to your other planet. You have to accelerate to 0.5c and then decellerate back to 0c (You don't want to just crash land into that other planet at 0.5c do you?) yielding a total deltaV requirement for any rockets of 1.0c. Suppose you have an 20 stage rocket. 10 stages to accelerate. 10 to decellerate. Each stage is responsible for a deltaV of 0.05 = 0.05*3E8 = 15E6 m/s.

 

The rocket equation tells us the required mass ratio for any stage given engine performance. deltaV = Vext * ln(MR). If we assume that the engine in question is 10X better than the best ion thruster on the drawing board today, we get.... 15E6 = 10 * 5000 * 9.81 * ln(MR). So... 30.6 = ln(MR) Which means that MR = e^30.6 which is approximately 19E12.

 

Oh my.

 

What does that mean?

 

It means that the mass ratio for each stage must be 19E12, of course. What does THAT mean? It means that the rocket's pre-ignition mass must be 19E12 TIMES it's burnout mass. In English?

 

If you want to push your space ship to 0.05c and your capsule (with you and all your food, etc.) has a mass of 1 kg (you've been on a diet, ok?), then your spaceship's final stage must have a mass of 19E12 kg. But that's just the LAST stage. The stage prior? Well, sticking to the math... 19E12*19E12 = 3.2E24 kg. Great, only 18 more stages to go. Long story short.... 19^8*10^(20*12) = 17E9*10E240... If I remember how all those powers and such work, that implies when your rocket leaves Earth it needs to have a mass of 1.7E249 kg.

 

For comparison, the Sun has a mass of 2E30 kg.

[michel123456]

That is not necessary. You just have to keep falling. Acceleration will be produced by some star or planet somewhere. Acceleration will not be produced by any engine and the spaceship will not have to carry any fuel or anything. In order to get the appropriate direction, the aliens only need to focus on the correct star*. (Its fantasy, isn't it?)

 

And relativistic calculation gives the acceleration as observed by someone far away observing the spaceship, or by the spaceship observing the fellow far away. In this fantasy, one could argue that the actual acceleration has nothing to do with what is observed.

 

edit

* deceleration is an issue. I guess the fantasy writer could imagine the alien spaceship focusing on another star (how he would do that is not so necessary to explain) or simply decelerating slowly by orbiting the goal planet.

Edited May 24, 2012 by michel123456

[mindless]

At 0.5c you are within about 15% of Newtonian approximations so I do not see the relevance of the relativistic calculation above. To travel at 0.5c you need to throw out sufficient mass behind the rocket to give your 1 tonne spaceship 1.5x10^8 m/s velocity. The rocket equation does not really apply here because Relativity comes to your rescue. You can increase the momentum of a small amount of matter, your fuel, to almost any value by accelerating it to near the speed of light. Your only problem will be obtaining enough energy to do the trick. Energy is conserved so you will need at least 10^3x10^16 ie: 10 million trillion joules to get up to speed. This would take the total matter-energy conversion of about 100 kilos. Not impossible but tricky .

Edited May 24, 2012 by mindless

[SRHBRU]

Traveling at the speed of light is impossible for us right now since we do not have the technology.

 

 

HOWEVER,

 

If we found a WORM HOLE, we could use that to travel to distant places across the universe?

[swansont]

Traveling at the speed of light is impossible for us right now since we do not have the technology.

 

Unfortunately this is like saying we do not have energy creation machines because we do not have the technology. But there's more to it: The science we understand says that the technology can't exist.

[robheus]

Interstellar space consists of roughly 2 hydrogen atoms per square cubic centimetre, and at near relativistic speeds, that is some real problem, because these atoms will hit the ship with enormous energies.

 

So realistic speeds limits for interstellar space ships are well below the speed of light.

[TransformerRobot]

Interstellar space consists of roughly 2 hydrogen atoms per square cubic centimetre, and at near relativistic speeds, that is some real problem, because these atoms will hit the ship with enormous energies.

 

So realistic speeds limits for interstellar space ships are well below the speed of light.

 

Then how do we repel those energies? Energy can't be destroyed but it certainly can be transferred, like in an electric current.