Game starting at 1979...

[TrashMan]

Definetly not stupid, you see, many religious people I know are well educated, perfectly productive members of the society. Actually, I find the ability to turn one's reasoning capacity off for a short period of time when it comes to their belief is well beyond me.

That's just it. There's nothing unreasonable about it. No one turns their "reasoning capacity" off.

That is why you have trouble grasping the idea.

***

One thing about the whole FTL travel thing - the theory is sound, but it's validity is..questionable.

After all, have we ever sent an object close to the speed of light to experiment? We had atomic clocks in an orbiting satellite, and we made some extrapolations from there. It is reasonable, but not really proven.

For all we know, and because of how we measure time, fast travel may have an effect on atoms, but not time itself (since we measure time by obsrving the half-life of elements)

Secondly - if we assume the measurement correct - just because time does slow down the faster you go, doesn't mean the function is exponential. For all we know the curve might as some point stop. Or reverse.

Mathematical formulas are all fine and dandy, but unless actual experiments prove them, they dn't hold much value IMHO.

***

And finally, this is about alien and tech, and somehow it devolved into FTL talk.

Bottom point - high technology is not some magical "I win" bottun.

Spearmen against a tank? Crappy odds at survival, but if there's enough of them...they CAN hurt the tank (jam things into the barrel/exhaust).

Nothing is ever fully armored. There is always weak spots and unarmored spot, as necessitated by the design and function.

And, if spearmen ever did close hte distacne to our modern infatrymen (let's assume an ambush), they could kill thme easily. Modern armor is not designed to stop spears.

[panzereich]

Technological advancement is not the be all end all. In fact, its a kind of trap.

Many of the great ruins that grace the deserts and jungles of the earth are monuments to progress traps, the headstones of civilizations which fell victim to their own success. In the fates of such societies – once mighty, complex, and brilliant – lie the most instructive lessons...they are fallen airliners whose black boxes can tell us what went wrong.

—A Short History of Progress

One of the best analogies I heard was huntsmen killing mammoths. Kill 1 great, kill 2 then that's advancement. Run the whole herd off a cliff and you have a progress trap created by technology. No more food because you were too good at catching it. This same theory can be applied to any civilization including alien.

Any civilisation that can get past nuclear war, environmental hazards and limitless energy consumption and then create FTL... I don't see why they would even bother invading. Would be like the gratification gained by an 8 year old burning ants with a magnifying glass. Kind of like the Matrix bs with humans being milked for their energy. Well sorry, but like any contained system energy out < energy in and entropy always increases.

A civilisation that simply expands and consumes is going to run out of resources. Lucky for us, there were many civilisations on planet Earth in the past. The fall of the Roman Empire may have caused a dark age, but we survived. Now life on Earth is dedicated to pretty much almost 1 civilisation. The global one. What happens when the lights go out and there is no one else left to carry a torch?

[HWP]

You actually misunderstood what I mean by agreeing with the clocks on Earth, by clocks I mean how we define a second on Earth.

Then there's no problem, it's defined the same way for you.

Both quotes comes from you, if you forgot. 5 years pass for you, 83.7 years pass for the slowpokes, yet time does not slow down for you?

Yes, time does slow down for you relative to the people on your home planet.

What problem do you see with that, for one-way trips?

Let's say you and your craft traveling at the speed of light to a distant star system to meet your new girl friend for a date

This is a space opera scenario, which as I said requires FTL handwaving.

claims to understand relativity inside out

No one understands relativity inside out. It is however possible to understand some of it and make the right conclusions.

edit: And apologies if I was being or came off as condescending or anything, it's just that it gets tiresome when people dismiss your posts without reading.

Edited October 25, 2012 by HWP

[HWP]

One thing about the whole FTL travel thing - the theory is sound, but it's validity is..questionable.

To clarify, use of time dilation is not really FTL. It's much slower than light.

The reason speed of light is considered such a fundamental limit is not that there's something special about light. Rather it's that light travels, in its frame of reference, instantaneously. So the idea of outrunning it makes no sense, you can't be faster than something that is instant.

c and the limit of v<c is rather a property of spacetime itself, in that it has no absolute simultaneity and any propagation in distance only happens with propagation in relative time.

For all we know, and because of how we measure time, fast travel may have an effect on atoms, but not time itself (since we measure time by obsrving the half-life of elements)

Secondly - if we assume the measurement correct - just because time does slow down the faster you go, doesn't mean the function is exponential. For all we know the curve might as some point stop. Or reverse.

Well, the thing it, time dilation is part of the very reason that speed of light even exists.

I.e., if the function behaved in a different way, or it didn't apply at c, or reversed, then light would propagate faster than it does.

"Time slows down" is a reasonable but not really accurate description. Since there's no absolute velocity, you can't say that moving fast has some effect on you. Rather it's that relative motion between two objects involves a shift in time between them, like two rocks in a pool of water producing waves don't get each other's wave instantly. At everyday velocities that shift is insignificant compared to static passage of time. At very high velocity time passing for the observer is determined by spacetime event propagation delay more than than by local time.

TL;DR version: Time dilation and finite speed of light are consequences of the same effect, one can't exist without the other.

And, if spearmen ever did close hte distacne to our modern infatrymen (let's assume an ambush), they could kill thme easily. Modern armor is not designed to stop spears.

Ceramic inserts are going to though... It's all the unarmored parts.

[TrashMan]

I still say that the whole concept of time and how scicne measures it is very suspect.

[yorak]

I'm not sure if I know why I even bother. Perhaps it's just that so many people read ten paragraphs (if that much!) about special relativity and think they got it all down, "oh, right, like a highway speed limit, thank you officer". While it's nothing like that, it's time itself that is at the center of this. It just requires wrapping one's mind around a few very counterintuitive things that go against how we normally think of space and time.

And let me repeat that nothing I've posted here is even slightly speculative.

I just wanted to come out and tell you that I'm glad that you bothered. I'm a PhD student myself (in Comp.Sci.) but as a hobby I have been studying some physics on the side. I'm taking modern physics course ATM and your explanations helped me to understand the special relativity a tad better than previously.

For you rest who still disagree HWP, reread what he has written. He is right you know. With a good power source "FTL" travel from the viewpoint of the traveller is possible. Given a good enough Newtonian rocket you can get from here to Alpha Centauri in less than a year. Just make sure you send a message to AC notifying that you are not going to make the meeting scheduled to late October 2013, because your trip there from their viewpoint will take a lot longer.

[panzereich]

Thanks Yorak, I understand now the effect that you both mention. This is still not true FTL travel.

An outside observer can easily calculate your speed as well under c regardless of what speed your onboard calculations might describe. Your not going faster than light. You get to your destination very quickly, but your not travelling faster than c which is the speed limit. What you describe doesn't require FTL, just the same effect that makes our heads grow older than our feet.

[StellarRat]

HWP is right. If you had a ship that could go CLOSE to the speed of light it would be almost as good as a ship that could jump into hyperspace, have warp drive, etc... The crew could cover great distance in little time TO THEM, it's just that people waiting for them to return, etc...would be waiting a very long time. Not the ideal ship for trade or vacations, but fine for exploration and colonization.

[Buzzles]

You know, for a game that's set in the late 70's, I'm seeing a disturbing lack of moustaches. A disturbing lack.

[yorak]

I agree with you Buzzles. Now that the problem with FTL is settled by hand waving (apparent) faster than c travel for the alien crew(s), I agree the biggest problem hurting the immersion is the lack of moustaches, platform shoes and wide legged jeans. So unrealistic...

[StellarRat]

You know, for a game that's set in the late 70's, I'm seeing a disturbing lack of moustaches. A disturbing lack.

Don't forget lamb chops and leisure suits...

[Turtlechef]

Well i have a brilliant tactic to defeat the aliens. Works in any era. Wait for the hidden movement phase, and while it's stuck, kill them all!

Just kidding, very interesting topic though, makes me think of the movie Zulu where the British were slaughtered by sheer volume not technology.

[TrashMan]

Ough...that avatar!

What have you done to Faye you maniac?!?!?!?

[Turtlechef]

She's mine now.! Buuaahahahahaha

[Raakku]

I still say that the whole concept of time and how scicne measures it is very suspect.

Only measuring of time that matters is the one that my bank is using to count the interest for my apartment loan.

[Gorlom]

To clarify, use of time dilation is not really FTL. It's much slower than light.

The reason speed of light is considered such a fundamental limit is not that there's something special about light. Rather it's that light travels, in its frame of reference, instantaneously. So the idea of outrunning it makes no sense, you can't be faster than something that is instant.

c and the limit of v<c is rather a property of spacetime itself, in that it has no absolute simultaneity and any propagation in distance only happens with propagation in relative time.

Well, the thing it, time dilation is part of the very reason that speed of light even exists.

I.e., if the function behaved in a different way, or it didn't apply at c, or reversed, then light would propagate faster than it does.

"Time slows down" is a reasonable but not really accurate description. Since there's no absolute velocity, you can't say that moving fast has some effect on you. Rather it's that relative motion between two objects involves a shift in time between them, like two rocks in a pool of water producing waves don't get each other's wave instantly. At everyday velocities that shift is insignificant compared to static passage of time. At very high velocity time passing for the observer is determined by spacetime event propagation delay more than than by local time.

TL;DR version: Time dilation and finite speed of light are consequences of the same effect, one can't exist without the other.

If you somehow managed to do the impossible and flip time dilation on its head, so that from an observers point of view the travelers experience of time passage would speed up instead of slow down, would the space opera scenario work (assuming some kind of stasis)?

It wouldn't be FTL travel, but it would appear to be to a stationary observer. would it not?

Edited October 27, 2012 by Gorlom

[HWP]

If that observer was using old star maps. When you are subject to velocity time dilation, the space around you decreases in size for you (GR explains it in detail), so from that observer's perspective the traveler's source would be closer.

There is no way for an object to travel a straight line from A to B before light from A reaches B. In all cases light will arrive first, even "warp drive" will create a temporary corridor for it.

As for how to turn it on its head... Well, time dilation causes delay for an object in accelerated motion, so it won't work for a stationary one (moving with constant velocity). So, to enable space opera flight, you would have to also put the source and the destination in accelerated motion. This should be doable by circular motion - basically, the people of this quasi-FTL universe would have to live on platforms orbiting very heavy stars from a very large radius. Though that raises a question of Schwarzschild dilation and it might have to be ridiculous to produce an appreciable effect, but should apply in principle.

This actually gives an idea for a dystopian science fiction setting where the working class lives in normal spacetime to maximize productivity and the "ethereal" ruling class in velocity-dilated, enjoying more goods produced by the former and the perks of quasi-FTL travel.

[Gorlom]

I was thinking more of having inverse time dilation affecting the traveler than forcing time dilation to affect the source and destination

As I understand it gravity has a time dilating effect too when applied in massive strength. Although I'm not quite sure how it works. would being inside a gravitational field (say a gravity well of a singularity) while counteracting the crushing effects still allow for the time dilation effect(to the same degree as if you weren't counteracting the crushing)?

what would happen with an inverse gravity well?

[Infinitum]

@HWP: Interesting. Quick question though, does your theorethical trip to Alpha Centauri take friction into account? What would keep your ship from being smashed by slightly sub-lightspeed (relative to the ship) hydrogen and space gravel?

Also, how would the crew experience time in relation to the distance to Apha Centauri after you've passed the halfway point and inevitably have to flip the ship around in order to decelerate (assuming you'd want to do such silly things as slowing down)?

[HWP]

As I understand it gravity has a time dilating effect too when applied in massive strength.

what would happen with an inverse gravity well?

Yes... but it works in opposite to velocity dilation, it 'speeds time up', so that won't help.

Inverse gravity is really opening the lid off the can. It can only exist with exotic matter (not known for certain to exist), at which point you can talk about wormholes and warp drives. It's also hard to think of a way to stay around an inverse gravity well, since you can't just orbit it like a gravity well.

Also, how would the crew experience time in relation to the distance to Apha Centauri after you've passed the halfway point and inevitably have to flip the ship around in order to decelerate (assuming you'd want to do such silly things as slowing down)?

Deceleration would still maintain the time shift, although the extent of it would be decreasing rather than increasing, until your times meet with the star's.

Really, for most intents and purposes, velocity and distance behave as Newtonian for the traveler. You can largely leave aside SR and GR considerations, a starship captain can plot his travel time as if there was no "light barrier", because, for him, there isn't.

@HWP: Interesting. Quick question though, does your theorethical trip to Alpha Centauri take friction into account? What would keep your ship from being smashed by slightly sub-lightspeed (relative to the ship) hydrogen and space gravel?

The interstellar space is pretty empty, not a lot of gravel there. Interstellar hydrogen density is extremely small, you need about 0.6 billion km^3 of space to collect 1 gram of hydrogen. For a ship 28m in diameter (600 m^2 in cross-section), that's 1 trillion km, or 0.1 light-years. So you can expect to encounter about 40 grams of hydrogen in the fast part of your journey. At an average Newtonian velocity of 2c, that's a total momentum of 0.04*6e8=2.4e7=24 million kg*m/s. If your ship is 25m*100m in size and has an average density of 120kg/m^3, consistent with aircraft, it should weigh about 6,000 tons. That gives a deceleration of 24e6/6e6=4m/s. Just 4 m/s lost to drag.

For anything dangerous you might encounter, you'd want Whipple shields (stacks of thin plates) protecting the fore of your ship. Since you still see things at light speed, you can and should have sensors to detect anything large, probably using a radar, and vaporize it with a laser. Vapor will spread out due to internal pressure, and thus around the shield.

Energy-wise it's a little more of a concern. At 2c, with an energy density of 1.8e17 J/kg, you'd encounter about about 0.6e-9 kg/second of hydrogen. That's an energy of 1e8 joules, which is 2.4kg of gasoline or 24kg of TNT. Fortunately for you, it's delivered more like the former, and spread over the whole 600m^2 at 167 kW/m^2. That's a lot of energy, so your fore would heat up to about 1400K. Or 1,100C or 2000F. At 3c it's about 1,400C.

But that's not really outside the limits of known materials. Tungsten would take 2c, but for both weight and protection reasons I think your Whipple shield would have to be mostly constructed out of silica aerogel rather than metals. Aerogel is better for the purpose anyway.

Yeah, we definitely aren't talking 1950s tech for a flight to Alpha Centauri, but 2050s... if we really wanted to, why not, to think about it. A sufficient nuclear power source should be more within the bounds of possible by then.

Though we're still talking about a ship carrying a whole lot of fuel and working mass for just a small crew compartment, and that's for a one-way journey. Going back will be harder, so much harder that the crew might have to become heroes or at best hope that in the dilated time we build a vehicle to rendezvous with them for rescue. If there is to be a crew at all, robots make things so much easier.

[Gorlom]

Yes... but it works in opposite to velocity dilation, it 'speeds time up', so that won't help.

ok, now I'm not really sure what you mean here. I find your formulation a bit confusing. I don't know to what you are referring.

Does a normal gravitational force have an opposite time dilating effect to velocity time dilation? (wikipedia claims it's the same effect, both slow time as they increase, but says that it has the reverse impact on an astronaut they used in a prior example, because he is affected by less gravity than the observer on earth.)

Or were you saying that the inverse gravity well would have the "speed up" dilation effect? It is the speed up effect that I am after mind you.

I'm assuming that if you can cause reverse time dilation (through means other than velocity) you can take your time and get there over the course of many years for the traveler but only have taken a small amount of time for observers.

Inverse gravity is really opening the lid off the can. It can only exist with exotic matter (not known for certain to exist), at which point you can talk about wormholes and warp drives. It's also hard to think of a way to stay around an inverse gravity well, since you can't just orbit it like a gravity well.

Magnetic boots.

No, I just assumed that you would build the ship around the inverse gravity well (maybe a Dyson sphere or something similar?) so that it couldn't really push you away because it was pushing another part of the ship in the opposite direction. And you would have handwaveium/adamantium/unobtanium so the ship wouldn't tear apart.

Unless you can somehow counteract any (anti)gravitational effect without missing out on the "speed up" time dilating effect.

Edited October 28, 2012 by Gorlom

[HWP]

Does a normal gravitational force have an opposite time dilating effect to velocity time dilation?

Rather that inverse (if it even existed) would.

I'm assuming that if you can cause reverse time dilation (through means other than velocity) you can take your time and get there over the course of many years for the traveler but only have taken a small amount of time for observers.

Time will 'speed up' for you, but it won't help the observer. Rather you'll take more internal time, as the universe will become larger for the traveler.

What the observer sees isn't affected by space around the traveler, with the exception of using a "warp drive", or Alcubierre metric, which is a bit of a cheat. In all forms of quasi-FTL, light is going to get through faster than any object.

[Gorlom]

Edit: decided to move this to PM instead.

Edited October 30, 2012 by Gorlom

[LittleNicky]

Professor Michio Kaku once stated that any extraterrestrial civilization that are capable of interstellar travel is at least thousands of years ahead of us in terms of technology. How on earth do we present a military challenge to such an advanced civilization back in 1979 is beyond me...

Everything else is fine tho, keep up the good work.

I like the time they set it in. gives it a retro feel. too many games now are all future based and gets boring.

[StellarRat]

Edit: decided to move this to PM instead.

Gorlom, I highly recommend "Einstein's Universe" by Nigel Calder and "A Brief History of Time" by Steven Hawking if you want a couple of really good books that a layman can understand. There is no complicated math, just an explanation of the concepts of relativity. I learned a huge amount from the first book in particular.