Poll: Energy and Entropy.

[Pyrian]

Dark Energy: Nobody really knows much about it, but right now it's modeled as a cosmological constant (a property of space itself), meaning that the amount of dark energy is literally the volume of the universe, and the amount of dark energy in a given area (say, the observable universe) is the volume of that area. This tells us that the amount of dark energy is constantly increasing (since the universe is expanding), and that it's also in absolute thermal equilibrium (since its constant over space) meaning that it adds no free or usable energy whatsoever.

STL would be taking 600 years to cover 600 light-years.

Look, we're talking about relativity, here. Don't just drop the frame of reference. You'll inevitably conflate things that just aren't the same. Assuming you mean a stationary frame of reference, that's still wrong; if the ship covers 600 light years in 600 years, you're traveling AT light speed, which is strictly speaking quite a bit different from STL or FTL - differences which are important and should not be glossed over.

I am talking about FTL reducing that to a few minutes...

When tachyonic FTL reduces that to a few minutes of stationary time, the time experienced by the traveler goes negative - something like 600 years negative.

...and saying you wouldn't arrive in our telescope vision that day because what they would be looking at is already an additional 600 years past.

There are actually some very interesting things you can elucidate by talking about "telescope vision", but I don't think this is one of them. Right now it seems to me that you're just introducing complications to muddy the waters. It's simpler to have the departure and destination be the same place, and it's simpler to talk about the stationary frame of reference than to talk about what a person with an impossibly good telescope is seeing.

...I would believe you could use FTL to travel to yesterday, no problem, but I think you need even more acceleration for a true timewarp.

I don't see how traveling to yesterday isn't a true timewarp, and I don't see how "even more" acceleration than FTL is even a meaningful statement (even more than greater than c?), nevermind how it's a solution to anything.

The calculation is fed into the navigational system and you head off, but when your circle is complete, you don't find the Earth. Why? ... Your drive is designed to get you there now.

This is just normal navigation. Making sure your destination is going to be where you're going when you get there is a standard problem in any traversal of orbital mechanics; running the numbers backwards changes very little. Traveling into the recent past makes the problem easier - we guess at where things are going to be, but we measured where they were. In any case, you typically allow some leeway to adjust your course mid-flight.

Some physical law is getting in the way.

We're talking about FTL. We've already broken more than a few physical laws getting there. Does one or two more really hurt anything?

 

[Terminal Blue]

*Thinks on that*

Theory: Perhaps gravity is the point. Dark matter is dense and therefore has a kind of pull because of its weight. Perhaps dark energy is to gravity what photons are to light, thus gravitational force throwing things around.

This is where we start to reach the limit of my understanding but..

The hypothetical gravitational equivalent of a photon is a thing called a graviton. if they existed though, gravitons would only create the force of gravity, which just pulls things together. You'd still need something else to explain things flying apart.

 

[FalloutJack]

Snip

I think perhaps I maybe misunderstood what you meant by STL, since I don't remember anybody ever mentioning it before. Could you stretch out that term so I can see the words, please? You may be right about some things there, but in order to have full comprehension, I need a bit of clarification.

Snip

Hmmm. You make a point. I already stated that even random bits of coffee will gather together in Zero-G. Well...either it really is adding on and on, which might indicate a white hole phenomenon (putting things BACK into the universe), or the gravity that binds and orbits and spins us is actually so great that it threatens to fly apart from the centrifugal force. When studying dark matter, there was a theory that without the ring of it around our system, Pluto might actually lose orbit, possibly other outlying planets. Just thinking out loud there.

 

[Zen Bard]

If you opened up a wormhole to cover 600 light-years instantly, you still wouldn't be on the telescope for another 600 years, because you went to present-day 600-year-away space, and the light will take that long to reach us to see it, meaning that you would miss the past because it was still our present, while our telescopes are looking at the past. Light acceleration has allowed for some weird effects and I would believe you could use FTL to travel to yesterday, no problem, but I think you need even more acceleration for a true timewarp.

I'll give you an example. Same distance, similar problem, but taken like this. We are on different planets, 600 light-years away. Breakfast time on our world is at the same time and you decide to join me for lunch. No worries. You just crank up your superluminal drive and zip on in. But then, you say, "I think I'll go back to Woodstock. I'll just travel in a circle according to precise calculation and get here on Earth before I left.". Before I can say anything, you head off to your ship.

Jack m'boy, I can tell you read a lot of science fiction. And someday, I'd love to compare libraries with you. But there comes a time where we have to separate the Science from the time-wimey, wibbley-wobbly, bibbity-bobbity buzz words, else someone may ask you to become the new showrunner for Doctor Who (actually...I'd be okay with that).

First, there's a difference between speed and acceleration. Speed is a change of distance over time ("miles per hour", "feet per second") whereas acceleration is the change of speed over time (meters per second squared). So the term "light acceleration" meaningless. Light has but one speed, and that's 3x10[sup]8[/sup] m/s.

That is, as far as we know, the Cosmic Speed Limit. But more importantly, it's the Universal Constant against which Relativity is measured. So throwing out words like wormholes and dark matter aren't really relevant (well...the strings might be).

But, if we're talking about warping time, it ain't speed we need...it's mass. We know there's a relationship between gravity and mass and have evidence that gravity can warp space. So it stands to reason that high gravity could warp the Four Dimensional Space-Time that is our Relativistic Universe.

Now, one way we can increase something's relativistic mass is through mass dilation which occurs as we approach the speed of light. But that wouldn't necessarily send you back through time so much as just really slow down time around you. And surpassing the speed of light wouldn't necessarily help either. In fact, mathematically, your mass would actually decrease.

(If you figure E=mc[sup]2[/sup], that means m=E/c[sup]2[/sup]. There are a complicated set of algebraic equations derived from this, but I'll be damned if I'm going to pull out my Modern Physics textbook for you, Jacko. The thermo flashback was too much! )

I think the idea that we're here to figure it all out is a very nice to be. I just figured we were out of good hypotheses, at he moment, for this. If I'm wrong, no worries, but still I like that idea, and I don't wanna spitball low-blows or something here. This is for pleasure.

Absolutely! Nice to see all the science minded people here actively participating in a fun and thought provoking conversation. There are only so many Forum Games and "Ban This Guy" threads one can take...

 

[infohippie]

An interesting - if worrying - thought, though the light itself seems to break its own record by not being a constant, but in acceleration itself.

Not quite. The light is traveling at a constant velocity, the space it is traveling across is expanding underneath it faster than the light travels.

 

[FalloutJack]

Snip

I was not a science major and I think you and everyone else can forgive that. The best way for a guy who is only savvy, not expert, to understand these things is to discuss, so thank you for that. As you'll note, I am crossing all this theory with actual science that I know, and just sort of letting myself work from there.

Also, what gave me away? The fact that this whole discussion started with Isaac Asimov?

An interesting - if worrying - thought, though the light itself seems to break its own record by not being a constant, but in acceleration itself.

Not quite. The light is traveling at a constant velocity, the space it is traveling across is expanding underneath it faster than the light travels.

The reason I heard differently is that because light is affected by the presence of a high gravitational force (a black hole, for instance), it would suggest that it was able to be dragged or thrust, dependent on the direction of forces. I recall hearing about a star that suddenly, and temporarily, became brighter when observed when seen through a telescope. It was either because a black hole or a clump of dark matter, thus the light was enhanced, meaning it reached us in greater force to be seen.

 

[infohippie]

An interesting - if worrying - thought, though the light itself seems to break its own record by not being a constant, but in acceleration itself.

Not quite. The light is traveling at a constant velocity, the space it is traveling across is expanding underneath it faster than the light travels.

The reason I heard differently is that because light is affected by the presence of a high gravitational force (a black hole, for instance), it would suggest that it was able to be dragged or thrust, dependent on the direction of forces. I recall hearing about a star that suddenly, and temporarily, became brighter when observed when seen through a telescope. It was either because a black hole or a clump of dark matter, thus the light was enhanced, meaning it reached us in greater force to be seen.

Yes, light is affected by gravity. It doesn't affect its speed, just its direction. General relativity tells us that mass curves space and this is what we call gravity. Light follows this curved path because from its perspective the path is straight. Light just keeps moving forward at a constant speed, it doesn't care that the space it is moving through gets warped, stretched, twisted, or whatever else.
What you are talking about is called gravitational lensing, where a large enough mass can curve space enough for it to act like a lens.

 

[FalloutJack]

An interesting - if worrying - thought, though the light itself seems to break its own record by not being a constant, but in acceleration itself.

Not quite. The light is traveling at a constant velocity, the space it is traveling across is expanding underneath it faster than the light travels.

The reason I heard differently is that because light is affected by the presence of a high gravitational force (a black hole, for instance), it would suggest that it was able to be dragged or thrust, dependent on the direction of forces. I recall hearing about a star that suddenly, and temporarily, became brighter when observed when seen through a telescope. It was either because a black hole or a clump of dark matter, thus the light was enhanced, meaning it reached us in greater force to be seen.

Yes, light is affected by gravity. It doesn't affect its speed, just its direction. General relativity tells us that mass curves space and this is what we call gravity. Light follows this curved path because from its perspective the path is straight. Light just keeps moving forward at a constant speed, it doesn't care that the space it is moving through gets warped, stretched, twisted, or whatever else.
What you are talking about is called gravitational lensing, where a large enough mass can curve space enough for it to act like a lens.

Yes, much as a black hole may fling that which misses its mouth far out into space. Aren't these things moving much faster?

 

[infohippie]

Yes, much as a black hole may fling that which misses its mouth far out into space. Aren't these things moving much faster?

Only if they have mass. Photons do not have mass (though they do have momentum) and they travel at a fixed speed. It is this fact that rests at the bottom of all the really weird predictions of special relativity, such as time dilation, and so far we have experimentally verified all or almost all of its predictions.

 

[FalloutJack]

Yes, much as a black hole may fling that which misses its mouth far out into space. Aren't these things moving much faster?

Only if they have mass. Photons do not have mass (though they do have momentum) and they travel at a fixed speed. It is this fact that rests at the bottom of all the really weird predictions of special relativity, such as time dilation, and so far we have experimentally verified all or almost all of its predictions.

That's weird. I thought photons were at that weird stat of being a little of Column A and B, scientists having a bit of an issue stapling that down.

 

[infohippie]

I think you're thinking of the wave/particle duality. Whether you treat photons as waves or as particles, they still have zero mass. Funny thing with that, all subatomic particles display this dual nature when it is looked for. Electrons are both waves and particles, so are protons, muons, neutrinos, everything. Even entire atoms, under some circumstances.

 

[Pyrian]

STL=Slower than light. Sorry about that.

Photons have relativistic mass (which is basically just saying they have energy) but not rest mass; colloquially, we usually refer to rest mass.

 

[FalloutJack]

I think you're thinking of the wave/particle duality. Whether you treat photons as waves or as particles, they still have zero mass. Funny thing with that, all subatomic particles display this dual nature when it is looked for. Electrons are both waves and particles, so are protons, muons, neutrinos, everything. Even entire atoms, under some circumstances.

I might be, at that. It happens.

STL=Slower than light. Sorry about that.

Photons have relativistic mass (which is basically just saying they have energy) but not rest mass; colloquially, we usually refer to rest mass.

Ahhh... Therein lies the confusion, both fronts. Well anyway, you may be right about that kinda' travel. Best way to know would be to do, though admittedly the methodology is a bit complicated.[footnote]Understatement of the year.[/footnote]

 

[Zen Bard]

I was not a science major and I think you and everyone else can forgive that. The best way for a guy who is only savvy, not expert, to understand these things is to discuss, so thank you for that.

Absolutely! The best way to learn is to ask. And I thank you for the opportunity to dust off all those cool things I learned in school but don't get to use much.

Also, what gave me away? The fact that this whole discussion started with Isaac Asimov?

Well, that and your wonderful vocabulary of sciencey sci-fi terms!

The reason I heard differently is that because light is affected by the presence of a high gravitational force (a black hole, for instance), it would suggest that it was able to be dragged or thrust, dependent on the direction of forces. I recall hearing about a star that suddenly, and temporarily, became brighter when observed when seen through a telescope. It was either because a black hole or a clump of dark matter, thus the light was enhanced, meaning it reached us in greater force to be seen.

Infohippie already addressed this, but just to repeat...it's not the velocity of light that's being affected by gravity but it's direction.

Imagine you drew a straight line drawn on a foam mattress. Now plop a bowling ball next to the line. Notice how the line looks curved? Well that's because the plane of the line was warped by the weight of the bowling ball. Same thing happens to light near massive objects in space.