BellGab.com Archive

Quote from: Tarbaby on July 18, 2014, 12:20:41 PM
Yes, dPS, but as your fuel supply approached infinite mass at least you would have an infinite supply of fuel.

I'm trying to remember if the speed of light constant limits the universes rate of expansion. No matter how good our new giant telescope is we would never see the front wave of the big bang because the universe is expanding as fast or faster than the speed of light so the light rays would never get here. Unless we could cheat by folding space. Which reminds me, I meant to ask Steller about that. He or she has a thread about it. But I could see AO telling me know the speed of light limitation does not relate to the rate of universe expansion because it is inside the bubble and does not pertain to physics outside the bubble. Or he may say it does.

There is no constraint on the rate at which space can expand. As long as nothing within that space moves faster than the speed of light locally you're okay. Galaxies can become separated in a way that signals can't be passed between them because of the expansion of the Universe.

In regards to spaceships traveling in opposite directions think of it like this: if the spaceships go for a long enough time (billions of years) then the distance between them is going to be large enough to start being affected by the large scale expansion of the Universe. Then their signals will get redshifted out of the observable range and any further communication between them will be impossible.

Quote from: Tarbaby on July 18, 2014, 12:20:41 PM
It's like the Schrodinger's cat enigma. I can't predict what AO is going to say.

lol

Quote from: wr250 on July 18, 2014, 12:24:02 PM
yes i understand the above.

The short answer is no, it's not twice the speed of light. But I wanted to give a more meaningful response than that.

Quote from: DigitalPigSnuggler on July 18, 2014, 11:48:06 AM
I would like to toss a related idea into the discussion.  When I was young, I came up with all kinds of fanciful plans for powering a spacecraft past the speed of light.  I approached it as an energy supply problem, which in a sense it is, but not in the way that I imagined.

What I learned is that an object acquires mass as it moves faster.  This is due to the equivalency of mass and energy.  An object that is set in motion acquires kinetic energy, and since energy and mass are equivalent, the mass of the object becomes higher than when it is at rest.

This doesn't have much practical effect for most of us in our daily lives, and in fact doesn't really start to show much at speeds below 50% of the speed of light.  At about 90% of the speed of light, though, the effect becomes very significant.  And this becomes the problem: as the object gets closer and closer to the speed of light, the mass of the object gets larger and larger, requiring more and more energy to move it ever faster.  As the speed of the object approaches that of light, its mass approaches infinity -- and it would take an amount of energy approaching infinity to continue to speed it up.

To my disappointment, I realized that it didn't make any difference how big my matter-antimatter rocket engine was.  It couldn't supply enough energy to push my ship past the speed of light.  Nothing could.

That's when I gave up and started drinking instead.

A bit of fine detail, but the mass increase you talk about is from a very specific definition that's not widely used anymore (see the "controversy" section here, http://en.wikipedia.org/wiki/Mass_in_special_relativity). Proper mass (the mass of a given observer that can be directly measured, see http://en.wikipedia.org/wiki/Invariant_mass) is invariant and does not change (it's the m in mc^2). Relativistic mass can be confusing because it's not true that moving really fast can make something become a black hole (it would have to be a black hole in all reference frames). So it's better to think in terms of energy and invariant mass and clears up a lot of confusion.

But ultimately any way you slice it you are right and your alcoholism is indeed justified - it does take an infinite amount of energy to get anything up to even approach light speed.

And a quick note, once again things are getting crazy so I will be scarce around here for the next few weeks, but I will try to keep on posting one sentence replies and (hopefully) interesting links once in a while.

Quote from: wr250 on July 16, 2014, 09:06:35 AM
i have a question, related to the speed of light.
if spacecraft a is moving at the speed of light (c) in one direction and spacecraft b is moving at c in the opposite direction, isnt  the speed of separation 2c ? and therefore no known communication is possible between the 2 craft nor can they see each other as the light from either will not reach the other? (assuming no warpage of space/time faster than light particles etc)
i base this on c being relative to the observer. probably way off base, but wanted to ask.

Okay, this is really an excellent question. It strikes at exactly the heart of relativity. I will also use a tiny bit of very simple math here to make a nice example. But please don't get scared off! The answer is surprising and it makes a great example of what relativity changes for our understanding compared to out intuitive, Newtonian Universe.

So the question is what does it mean for two objects to travel apart from one another at speeds approaching the speed of light, and can the objects communicate with one another using light rays (or any other electromagnetic signals that travel at the speed of light)?

In our day to day life we live in a low velocity world so we're used to thinking of velocities adding together linearly in the way you did above. This makes sense to us because it works when the velocities are small with respect to the speed of light. So let's say one rocketship has speed u and the other v. They are going directly away from one another. The intuitive Newtonian view that we have is to add the velocities together, such that each one would see the other going at a speed we'll call s, where s=u+v. If you think about it this makes sense. If you've ever thrown anything out of a car window in the direction you're moving you'll notice the thing you threw went in front of the car, because you add the speed of the thrown object and the speed of the car together. This makes sense and is intuitive. Adding speeds in this way is called a Galilean transformation because Galileo was the first one to actually write it down. Using a Galilean transformation we expect each ship to see the other going at u+v.

However, as speeds get closer to the speed of light we find something strange going on. Our notions of distance and time start to change because of two effects - time dilation and length contraction. These effects are too small to be noticed in every day life because we move so slowly. But they begin to become significant as we move with speeds that approach light speed. The change in distance and in time conspire together to keep the speed of light, c, the same for everyone regardless of how fast they are moving. It means that the Galilean transformation law - and our intuition - must be wrong! The correct addition law, given by special relativity, looks like this:
s=(u+v)/(1+u*v)
I used * to show multiplication here, and I'm also using units of speed that are with respect to the speed of light, so 0.99 really means 99% the speed of light. This addition law shows us something surprising. First, if u and v are both small, their product u*v is small so then the denominator is close to 1. This means we get back the Galilean s=u+v for low speeds - our familiar world - as we would hope. The surprising thing about it is that when the opposite happens, as we go close to the speed of light, u and v both get close to 1 and so does s, so we can never see any object moving faster than this speed. In fact, for any two speeds u and v that are both less than the speed of light, the speed they will attribute to the other, s, will also be less than the speed of light. So this is the ultimate speed limit for anyone moving through space-time.

As an example let's say both our ships are moving at 99% the speed of light, so u=0.99 and v=0.99. The naive Galilean transformation and our intuition would say that the resulting speed should be s=1.98 so no signal can get from one ship to the other at the speed of light. However, the relativistic addition law says s=0.9999. So each ship actually sees the other moving at 0.9999 times the speed of light, and since this is slower than the speed of light, a signal CAN make it between them! This means that even though both ships are themselves traveling at 99% the speed of light, observers in each would see the other moving slower than we would expect intuitively!

As an aside, let's talk about the assumption we made above that the speed of light must be the same for every observer. Why must this be so?

This is really an elaborate way of saying the laws of physics must be the same for everyone. Light itself is just the solution to a wave equation made from Maxwell's equations of electricity and magnetism, that travels at the speed of light. These equations are true for all observers, regardless of their state of motion. So it must be that each observer in relative motion with respect to one another find this same solution and the same speed of light. Otherwise, if you could pace a light ray, you would not see it as a wave traveling at c anymore, you would see it as some strange "thing", frozen in time and also inconsistent - there are no charges around to support a static distribution of electric and magnetic fields like that. So then it would mean that Maxwell's equations were wrong for the person moving that fast. But this is not so, and we can measure their effects and predictions at high speeds and we never find anything like this. So, Einstein said, if each observer measures the same speed for these wave solutions it must be that each observer sees the same speed of light, and our intuitive understanding of how velocities add, and what space and time mean MUST BE WRONG. And all of the experiments and tests we can do hold this up - Einstein's theories are now among the most well tested in all of science.

Quote from: zeebo on July 16, 2014, 06:50:22 PM
If I'm understanding "unbounded" right, it does sound mathematically distinct from a truly "infinite" universe.  And it would mean theoretically, as M. Kaku says, that the farthest place from you in the universe is the back of your own head.   

Yes, the same way a sphere is finite but unbounded. You can go around it as many times as you like and never hit a wall or boundary.

Quote from: area51drone on July 16, 2014, 09:17:57 AM
Agent, what does it mean, in terms of time, when space expands?

The way the expansion of space is normally thought of is in terms of a scale factor. This scale factor is time dependent, and it increases with time at a rate that depends on the amount of matter and energy in the Universe, the cosmological constant, etc. The scale factor is related to Hubble's constant.

Here is a good example of what the scale factor means physically: Imagine that you draw a triangle from three galaxies at the corners. Then as time goes on the universe expands and the galaxies get further apart. The scale factor gives you the increase in the area of the triangle as a function of time.

Quote from: Mind Flayer Monk on July 17, 2014, 06:33:46 PM
[attachimg=1]

from http://chainsawsuit.com/tag/cthulhu/

That's brilliant!

Quote from: jazmunda on July 16, 2014, 06:42:56 AM
They're all excellent ideas.

Unfortunately I'm all out of poop .... stories.

haha
Well in that case the next gabCast honors poop when Jaz goes live on air, making the flush at the end of the show all the more significant.

Quote from: SciFiAuthor on July 16, 2014, 02:59:03 AM
I heard that and wondered "ok, but, if it goes on forever then what is space-time expanding into?"

I don't care that matter distribution is expanding, I care that space-time is expanding. We can look out and see pretty early into the universe's history. There must be a demarcation line between the line of the big bang's expansion and the line of space-time expansion. Sure, she might mean that if you head out in any direction and cross the universe you'll end up back at the same point. But that's unsatisfying. The rules in the bubble bring you back to where you started, but that doesn't mean that you're not in a bubble.

Since it's accelerating and expanding you'd never be able to reach beyond the local horizon even if you left at the speed of light today! You're stuck within our local observable part of the Universe.

And you can't say it's expanding into anything! All time and space are measured with respect to the big bang, so the best we can imagine is that it's expanding like a surface. Sorry I can't get more in depth right now (gotta get in to work!) but this article looks interesting and says what I was trying to in a short period of time.

http://www.universetoday.com/1455/podcast-what-is-the-universe-expanding-into/

It's true it has been measured to be flat within a very large degree by observations of the CMB. This means the matter and energy density is very close to the critical density to keep the universe from collapsing back in on itself. So the question why is it this specific value became very curious and the way out of a "natural-ness" problem is to have something like inflation happen in the early universe. The side effects of inflation may have already been seen in the BICEP2 observations but now these observations are being called into question (rightly so). We've known since the late 90s that the Universe is accelerating and this adds a new wrinkle to our understanding of the shape of the Universe. Which is a whole other topic...

We are limited in what we can see of the Universe because of the speed of light, we can only see events from a certain distance away because it takes light a finite time to get to us. So when we talk about the Universe we really mean the observable Universe which is basically a globe centered on the observer. The boundary is defined by the cosmic microwave background and has a redshift of around 1100. It is this patch of Universe - within this bubble - that we measure to be flat. It's thought the Universe is a lot bigger than this but since we are causally disconnected from regions outside they cannot affect us since we can't get any influence from them due to the finite speed of light. So it's not known what the topology of the larger Universe is, but inflation suggests that it is finite but unbounded - possibly like the surface of a large sphere. Our flat looking patch is then just a very close up "view" of a part of this expanding bubble.


Hope that was not too long winded

I'd like to suggest Bateman as a guest. It would be interesting to hear about how he began in pod and his past experiences on the air. I also second Uncle Duke as a future guest as well. Also, both Astroguy and Expat would make great guests, let's hear their personal experiences dealing with and running sites about bad astronomy.

Hell, I'm sure interviews among the hosts would be interesting too. Take an hour to get Onan's opinions on the current trends and habits in fad eating, how technology plays a role in medicine (3D printing organs omg) and how that will change our perspectives on life as such things become more ubiquitous in our future. After his trip to LV, get Jaz' opinions on the difference in culture between America and Australia! You could easily get a show's worth of material out of that. You could also interview Jaz about poop

Quote from: basswood on July 15, 2014, 01:01:32 PM
... what else?

Glow-in-the-dark Cthulhu dice

Quote from: jazmunda on July 13, 2014, 03:40:57 PM

http://en.wikipedia.org/wiki/David_Berkowitz

Sorry I went so dark

Quote from: SciFiAuthor on July 11, 2014, 11:11:44 PM
Aw man, can't you cook the numbers or something to add in some turbulence? It won't pass peer review, but the sci fi stories will be more fun. But it does create a question, what would the effect of nearby gravity sources be on the warp bubble? In other words, if a ship in warp bubble passes near a star, does the star's gravitational pull 1. draw the ship in the warp bubble out of the warp bubble or 2. does the warp bubble deviate along with the curve in normal space-time and the ship remain in the center due to the space-time in the bubble also warping from the gravity? This would be interesting to know, since it might provide a way of steering the warp bubble via gravity assist maneuvers or alternatively stopping the ship by bringing it out of the bubble if such a thing would be survivable.

Another thought comes to mind in regards to the flotsam the warp bubble picks up on the way. Does this flotsam actually enter the warp bubble, or adhere to it's surface or inside the wall, or does it collect in front of it? If it collects in front of it, or adheres to the surface, then wouldn't that material be in violation of the constancy of c given that the material is not within the warp bubble itself? Or might it prevent the warp bubble itself from ever exceeding c?

Go for the gusto, what happens if the warp bubble impacts a planet? But I suppose this would answer my above question. The particles presumably enter the wall and no longer are in normal space-time, and your calculation movie would illustrate how that process unfolds. 

The warp bubble travelers won't be able to listen to Jorch! If MV reads this, he'll have a warp bubble developed and enveloping bellgab within a week. Yes, it would be more realistic and interesting. Unfortunately the photon flux inside the bubble, while lower, would still all be high energy photons. As I understand it, while you couldn't look outside, you'd still get outside's dangerous radiation.

To go out into the weeds, if you ram the warp bubble into a star, then wouldn't the interior be thermally insulated? If the gravity doesn't collapse the warp field, and assuming the density of the matter surrounding it wouldn't be a problem, then one could theoretically create a warp bubble probe and explore the interior of the sun. I know this one's a bit "do you think asteroids have a brain?" but I'll toss it out there anyway.

This is why I ask if the material would violate c in some way if it's interacting with normal space still and prevent the bubble from ever going superluminal.

All good questions, it looks like the alcubierre metric has only been considered in the flat case with euclidean space in the bubble exterior and interior. The difficulty of some of these problems are that they involve the 2-body interaction, which is difficult to solve in GR at all. You usually have to go to a method called a post-Newtonian parameterization which chops up GR into small corrections that are added to Newton's mechanics to make it approximate GR, so even calculating the details of stellar collisions in full GR can be difficult. I have no real intuition for what would happen to the bubble in any of the cases that involve external interactions. I would guess that the bubble itself is small so you can treat it like a test particle in the field of the Sun. It also requires a specific matter density to establish so if you mess with that density distribution too much then the field should decay and you will begin to decelerate. Material particles can gather in the walls of the bubble but they are not perfectly confined there like a ram, they can pass through as well. So jumping into the Sun with one of these things wouldn't change the result much. Also the real difficulty is in getting a signal from the center of the bubble to the outside, which is what makes steering and controlling the bubble so difficult.

And you will be happy to know that the region of flat space inside the bubble varies as a function of bubble-wall width, and White's modification that NASA is testing involves shrinking the energy requirements by making the walls of the bubble thicker. Only at the very center there will be no gravitational effects... so practical warp drive may have you hanging on after all.

Quote from: zeebo on July 14, 2014, 09:35:57 PM
More warp drives firing off!  Ok ... possibly.

http://phys.org/news/2014-07-radio-burst-discovery-deepens-astrophysics-mystery.html

Those fast radio bursts are really interesting because the mechanisms behind the radio emission of pulsars is not well understood at all. The article also mentions magnetars which are incredible in every way. I'm guessing these are in some way related to neutron stars or some other kind of compact object.

Quote from: wotr1 on July 15, 2014, 04:20:53 AM
I honestly love this site.  Nowhere else will I ever run across somebody running this software.

I had never heard of abandonware until a few weeks ago when I read a journalists attempt to use DOS for a day on his computer with netscape? and he talked about abandonware.  It brought me back to a strange time before icons and when even microsoft used DOS as a base...

haha
I'm guessing it was this one http://arstechnica.com/information-technology/2014/07/dos-boot-ars-spends-a-day-working-in-freedos/

No chance for a gabCast with Eddie, WR250 and Onan live in studio?

Quote from: Camazotz Automat on July 11, 2014, 02:43:25 PM
A site devoted to All Martian Weather, All the Time!

I don't know about you, but just seeing the word "Martian" makes life better.

Wow. It's the future

Quote from: SciFiAuthor on July 10, 2014, 04:05:19 PM
I find myself imagining what a harrowing experience travelling in the first warp bubble might be. It might be something like hugging and maintaining an orbit around an artificial black hole that's warping through space, all with the risk that you'll end up tossed off and killed or sucked in and killed.

Should also add that space inside the bubble wall is as flat as outside the wall, so the 4-velocity of observers inside (at the center, anyway) as well as outside is the same. I think the wall is taken as thin in these papers too. Anyway that means no need to hang on for dear life, riding the warp bubble is as easy as sitting around in flat space as long as you sit at the center. That's why there's no time dilation for the party inside the bubble. It's like when you make the bubble you take a little piece of flat space-time that you started with along with you, that makes the inside of the bubble. Assuming you start in a flat spacetime.

Quote from: SciFiAuthor on July 11, 2014, 02:16:54 AM
So the "What if?" question that ran through my head this time is ...
... use a dense area ... plasma...

A few initial thoughts come to mind.

First off, it would be nice to see the paths of light rays and material particles entering and interacting with the bubble walls. The MLO paper does the calculation in 1D, but there's no reason why it couldn't be done in two, taking the xy plane through the center of the bubble. It's symmetric anyway so this is easy to code. Then use a 4th order runge-kutta scheme to integrate the light ray paths, the null geodesics and color them according to their gravitational doppler shift. Then do this for a set of time steps t and you get a little movie of what happens when photons run into a warp bubble. You can do it also for material particles on time-like paths. So then you get a visual representation of the situation, where particles gather and bunch up and what they do for various cases of the bubble speed (sub and super luminal). That would be pretty interesting and give a good intuition of how these things behave.

Then you could assume that space is full of plasma, take the simplest case of electrons and their antiparticles. Say the plasma is at a constant densty initially to keep things simple. As the bubble moves around, this plasma should gather around the bubble wall. It's more complicated because the bubble is no longer in vacuum so the equations would get more complicated but it would also be more realistic too. In fact, this would model the case above but taking particle density as continuous instead of discrete. It's interesting because it's known that photons have an effective mass when they travel through plasma (http://adsabs.harvard.edu/abs/1992PhRvD..45..525K). So how does this change the dynamics? And since it's moving through a plasma no photons lower than the plasma frequency can propagate so you would find in this case the photon flux inside the bubble is lower than the vacuum case. 

It's also interesting to think that if the wall collects plasma and miscellany as it goes then that will build up over time and eventually the external space won't be flat anymore around the bubble. What does that mean, and can it disrupt the bubble wall? If so then the range of any such bubble might be limited by the amount of material it can carry. I'd expect this to be huge because it takes a lot of energy to make the bubble in the first place.

The last two scenarios are much more complicated than the first, which I do think could be done with not much difficulty at all for someone that can numerically solve systems of coupled differential equations.

Quote from: zeebo on July 11, 2014, 02:42:52 AM
Hey guys after you get the warp bubble issue squared away, here's some more food for thought for y'all.  Who knows, maybe you can figure some of these out in your spare time.   

http://en.wikipedia.org/wiki/Unsolved_problems_in_physics

That list is both terrifying and exciting at the same time.

Quote from: SciFiAuthor on July 10, 2014, 04:05:19 PM
Three kinds of fascinating, you should write popular science books. You're able to concisely explain it without resorting to equations. I find myself imagining what a harrowing experience travelling in the first warp bubble might be. It might be something like hugging and maintaining an orbit around an artificial black hole that's warping through space, all with the risk that you'll end up tossed off and killed or sucked in and killed.

If I had the time I would like to try some writing, I think it would be a lot of fun. I have many ideas but other than technical work I haven't had much luck getting anything set down.

Quote from: SciFiAuthor on July 10, 2014, 04:05:19 PM
It's one of the few Clarke stories I haven't read yet, actually. I'll bump it up on the reading list.

Would be interested to hear your thoughts on it. I really loved the development of the story as I worked my way through it. Things were really excellently set up and taken to their logical conclusions in creative and interesting ways.

Quote from: SciFiAuthor on July 10, 2014, 04:05:19 PM
Interesting, a space-time equivalent to a sonic boom.

Not quite, all of the stuff that gets blown out of the bubble is pretty much picked up on the way, so your warp bubble gets "loaded" with shrapnel like dust, ions, subnuclear bric-a-brac as you go. Then once you stop all of that stuff gets a big acceleration in the direction of motion of your bubble. Electromagnetic radiation can get into the bubble and it gets badly blueshifted on the way through, making problems for anyone within. The big problem with the alcubierre drive is that it seems you can't get any signals out when you are traveing with a superluminal velocity. I should also say I don't think you can make the literal equivalent of a sonic boom because that requires exceeding c in the vacuum. 

BUT you ask a very interesting question here. Does the bubble also create and scatter gravity waves and can those be red/blue shifted by it's motion as well? There might be big gravitational wave flux as well from using one of these. When I get some free time I might go over McMonigal Lewis O'Byrne paper and try to find the answer to this. It's neither a static nor stationary metric so I would expect gravitational waves should be generated from it but I don't have any feeling for how they would behave.

Interesting questions.

Quote from: Camazotz Automat on July 10, 2014, 07:22:52 AM
So, if I understand this, it's similar to my being in a theater watching a movie.  The movie has started, then I tell my date to "watch my seat," which she does so dutifully.

I quickly storm the projector booth and turn off the film and wrestle the projectionist to the floor, applying a sleep hold.

I wait a few minutes until he begins to stir awake, at which point, I dash back to my saved seat.

I ask if I've missed much of the movie... she responds, "well actually, you didn't miss anything. Some kind of technical difficulty. We were all just sitting here for nothing."

Thus I have traveled the movie warp tube.

Am I even close metaphorically, if the movie itself equals space-time?

Hey actually that's pretty good! Then the movie itself is time and the distance you travel is between your seat and the projection booth

Quote from: wotr1 on July 09, 2014, 11:26:13 PM
No, no... I must have mistyped that.  What I meant was that the general layman believes would be the most important piece of equipment in your field only uses twice as much energy as a completely useless process called "bitcoin mining."  What produces only heat is a bitcoin miner.  Feed 1000 megawatt hours into it each day and come away with a few "newly minted" bitcoins.

I was simply meaning that you may find it particularly depressing to think that people spend 50% of the energy necessary to run such an amazing piece of technology that really does teach us something to product bitcoins (and heat...)  As a matter of fact, add in all of the other cryptocurrencies and the air conditioner (many large "farms" are hosted in data centers) and I bet the energy used to mine for virtual coins is more than that used to power the collider.  Hell, I find that thought depressing (and I run a miner in the corner...)

Can you imagine if people actually spent some of the time, effort, money an energy that is wasted on bitcoin to produce something useful.  (As mentioned, there is talkcoin and curecoin that seem to suggest that at least there are a few people asking if the hundreds of PH could be used to produce something useful...)

I really did not mean to suggest that the Hadron collider only produced heat- and I only brought the collider up because the comparison between it and bitcoin was used as example of the massive waste of energy  and was quoted in Forbes and Bloomberg awhile back.  I found it an interesting comparison between energy used for a purpose and energy wasted.  There was also a comparison to how many homes it would power... but that is useless as many people waste huge amounts of energy and it does not drive home the point nearly as well.  http://www.bloomberg.com/news/2013-04-12/virtual-bitcoin-mining-is-a-real-world-environmental-disaster.html

***Edit: is the Hadron collider really the most important thing in your field of work... or are there things that are not as discussed or hyped in the media that are more important?***

Those are some terrifying statistics.
The LHC is pretty much the cutting edge right now. My specific field is astronomy related so the Hubble, Chandra and other space-based observatories are most important to me personally.

Sorry, I must have missed what Curecoin and Talkcoin are?
And how many coins have you mined up personally?

Quote from: jazmunda on July 06, 2014, 11:34:01 PM
The city of Melbourne (my hometown) has a cultural festival using the Aboriginal word Moomba. It seems the festival's initial organisers asked the local Aborigines to suggest a name, and were told that moomba means 'lets get together and have fun.' The grateful organisers subsequently used the name.

In hindsight, the organisers really should have been suspicious that 'lets get together and have fun' could be expressed in two syllables. In reality, 'moom' means 'bum', 'buttocks', or 'anus', while the suffix 'ba' means 'in', 'at' or 'on'. So moomba actually means 'in the bum.'

This.... is so awesome

Well since we're speculating about warp drives, let me also throw this out there: Ever heard of a Krasnikov tube before?
http://en.wikipedia.org/wiki/Krasnikov_Tube
The space-time subway system!

Read the original paper here
http://arxiv.org/abs/grqc/9511068
and an extension
http://arxiv.org/pdf/gr-qc/9702049v1.pdf

and a nice (but old!) popular summary about the method here
http://www.npl.washington.edu/AV/altvw86.html

This method of transportation requires that a ship moving near the speed of light establish a warp in space-time as it travels (the "tube"). Then once at the destination the traveller that turns around and goes back through the tube again is sure to exit just after they entered! So this would require you to make a trip to some distant object, spend some time out there and then return to your own world and not the world of the far future, effectively erasing the majority of the round trip travel time. This requires you to have a way of travelling close to the speed of light, though, to make the tube in the first place. It does not eliminate one-way travel time but does eliminate most of the round trip travel time, but ensures a time-like separation on enetering and leaving. This means there are no time paradoxes and you cannot exit the tube before you entered it. Like the Alcubierre solution this type of warp drive also needs exotic (negative) matter to establish the warp. If such a tube could be kept stable then it would act like a subway tunnel through space and time.

Quote from: SciFiAuthor on July 10, 2014, 01:34:36 AM
I see, so to create the warp bubble you must also apply continuous energy to maintain it as you warp your way along. I'm rather odd in that faster than light communications are more important to me than faster than light travel. I want to talk to aliens, not contract VD from one. But the gamma ray idea is intriguing. Well, you know, every time we look at the gamma ray spectrum it seems to toss us some new phenomenon that we have to explain. There may yet come some odd burst where an artificial nature might be more likely than a natural one. They would be expending far more energy for something that might be more feasible than aliens just sending out terrawatts of radio signal just for the hell of it.

I think it's a certain amount of energy that's needed to generate the bubble but you need some way of keeping yourself at the center of it. So if you want to just send a particle you have to stick a particle to the drive itself, otherwise it will wander around and eventually get blasted away when you decelerate. It's a specific configuration and amount of mass that keeps the bubble formed but there's nothing keeping you inside the bubble unless you're actually holding onto the device itself. In other words, getting the required amount of matter in one place will allow you to twist up space-time the way you want it, you just have to make sure that you stay nearby that warp. That's basically how Alcubierre came to his conclusions, he found a solution to the metric and then worked backwards, giving a required matter-energy density (which turns out to be negative). All assuming the bubble could be controlled, of course.

Have you ever read "The Light of Other Days" by Clarke and Baxter? That book is a story about using wormholes for communication and the consequences of a faster than light communications network that is not limited by time or space. A really fascinating story that captured my imagination!

Quote from: SciFiAuthor on July 10, 2014, 01:34:36 AM
I wonder what the effect of a passing warp bubble might be on objects nearby. Could half the earth get dosed with fatal levels of gamma radiation just because some alien prick was speeding when passing through the solar system?

it sounds like that's what McMonegal, Lewis and O'Byrne were suggesting in their paper (
http://d1jqu7g1y74ds1.cloudfront.net/wp-content/uploads/2012/02/MatterOfMatter-revised-final.pdf). They discharge particles from the bubble region like bullets when they decelerate so you have to make sure where you're pointed when you stop. It's as if you let a shock wave go from the bubble itself, accelerating all the particles and dust you picked up on your journey.

Quote from: zeebo on July 09, 2014, 11:38:09 AM
That just blew my nerd mind.  I've decided it's so cool I'm going to believe it true until proven otherwise.

haha

Quote from: wotr1 on July 09, 2014, 02:28:22 AM

Somebody thinks they are worth something... Consider that just the bitcoin network presently has 120 PH (what is that, 120 quadrillion hashes per second?) If you are wondering, miners use up roughly 1000 megawatt hours a day producing virtual money (@ $.15 / KWh it should be around $150 000 spent each day to mine bitcoin alone in electricity + the cost of hardware.)  It could be a case of "the greater fool theory"- but it continues for now.  (If Agent Orange is reading this he may make note that is half of what it takes to run the most useful tool in his field- the Hadron collier and all it produces is heat...)

The LHCs main export is knowledge, not heat. In both scientific and engineering endeavors. Todays theory is tomorrows tech. 

Quote from: Tarbaby on July 08, 2014, 01:08:34 PM
Your voice sounds just like I imagined. A cross between Harvey Fierstein and Emo Phillips.

lol!!

Quote from: SciFiAuthor on July 08, 2014, 02:34:52 AM
Hmm, so my brain is still cranking away. Another application would be that the warp bubble should be able to convey information faster than light. In which case individual subatomic particles could be sent out as a sort of Morse code; proton, neutron, proton, neutron, proton, proton or something. Thusly, faster than light communications might be a possible use for it, but dealing with even smaller objects than a nanoprobe or the Enterprise. In other words, if White's work pans out, SETI should be looking for tiny warp bubbles carrying particles travelling through space for evidence of E.T. if such a thing would be detectable (I have no clue if it would be). You probably couldn't figure out their message, but if you see a warp bubble you'd know it's artificial (or would it be? Natural warp bubbles?)

So what do you think the energy requirement for sending a proton in a warp field would be? Is that getting down into manageable energy requirements enough for it to be feasible?

That's a great question. I'm not sure how the energy scales with distance or mass inside the bubble, I will have to take a look at the papers again. In order to produce an effect that small though you will need a full quantum gravity description, again. The device is really a demonstration of principle from GR, so anything below the "macro level" would be more complicated (and open the way ahead for some pretty dramatic research opportunities).

The problem with a communication network based on sending individual particles is that each bubble needs a device associated with it, so you're sending single particles attached to a warp drive, which is not efficient. Though you could make a broadcasting device that will relay a speed of light message once it makes it to a destination using a warp.

Some fraction of observed gamma ray bursts observed today could really be alien warp drives turning on and off millions of years ago due to the big particle and EM flux that comes from them