Gedanken...

Image Source: Pics About Space

Topics: Einstein, FTL, General Relativity, Star Trek

For the record: \\//_. Now that my "Trek creds" have been established...

Gedanken is a German word for "thought." It is often colloquially defined along with the word experiment, which is where a lot of the notions of Special and General Relativity took place in Einstein's mind; his innate ability to conceptualize a tough idea.

It is also by definition, an experiment that is impractical to carry out. Part of it being impractical is the incredible energies that would be needed to propel a star ship to even 0.10 c, or in Trek parlance: "impulse." An aircraft carrier is ~64,000 metric tons (I'm using it as my "Enterprise," which is supposed to be pretty big). That's 64,000,000 kilograms. Simply multiply it by 0.10 x 3.0 x 10⁸ m/s² this will give you the energy output in Joules: 1.92 x 10¹⁵. The PLANET in 2013 generated 5.67 x 10²⁰ Joules.

Part of the constant research is that sometimes what you're looking for may not be found, but the techniques you use in any analysis may have an application in areas you may not have imagined. As such, it becomes a part of the research one can reference and build on, thereby increasing the overall knowledge of a subject area.

Abstract

Warp drives are very interesting configurations in general relativity: At least theoretically, they provide a way to travel at superluminal speeds, albeit at the cost of requiring exotic matter to exist as solutions of Einstein’s equations. However, even if one succeeded in providing the necessary exotic matter to build them, it would still be necessary to check whether they would survive to the switching on of quantum effects. Semiclassical corrections to warp-drive geometries have been analyzed only for eternal warp-drive bubbles traveling at fixed superluminal speeds. Here, we investigate the more realistic case in which a superluminal warp drive is created out of an initially flat spacetime. First of all we analyze the causal structure of eternal and dynamical warp-drive spacetimes. Then we pass to the analysis of the renormalized stress-energy tensor (RSET) of a quantum field in these geometries. While the behavior of the RSET in these geometries has close similarities to that in the geometries associated with gravitational collapse, it shows dramatic differences too. On one side, an observer located at the center of a superluminal warp-drive bubble would generically experience a thermal flux of Hawking particles. On the other side, such Hawking flux will be generically extremely high if the exotic matter supporting the warp drive has its origin in a quantum field satisfying some form of quantum inequalities. Most of all, we find that the RSET will exponentially grow in time close to, and on, the front wall of the superluminal bubble. Consequently, one is led to conclude that the warp-drive geometries are unstable against semiclassical backreaction.

Physics arXiv: Semiclassical instability of dynamical warp drives
Stefano Finazzi,^1,∗ Stefano Liberati,¹,^† and Carlos Barcelo²

Warp Drives and Wormholes...

Topics: FTL, Space Exploration, Spacetime, Star Trek, Wormholes

Since the 1994 paper by Miguel Alcubierre (and the physics caveats to attaining it), there has been some interest in this area just because of the vastness of interstellar space and the limitations since the Mercury Space Program of Newtonian Space Travel.

Also, it is unlikely we will come in contact with 5-dimensional hyper-humans that want to see to their ancestors' survival by popping up a wormhole next to Saturn (note: not a spoiler to "Interstellar" by now).

The problem being addressed is species survival - dinosaurs were animals with small brains that had a really BAD day 65 million years ago. We homo sapiens (Latin: "wise man") are not. With our demand for energy and resources going unabated, and the fact that our neighboring planets are so far uninhabitable, we are reduced to several options:

1. Conservation and resource restrictions: This has proven untenable as our economy at this point in history has been based on scarcity and charging a premium for that scarcity.

2. Plus, we'd have to forgo our Victorian compunctions regarding birth control, and stop encouraging both large families and early teen motherhood by ignorance of the same.

3. Terra-forming other planets: Which, I guess is the attraction to Mars and the four presumed volunteers to a one-way mission to the Red Planet (good luck). Mars has no breathable oxygen/nitrogen atmosphere; it is roughly 1/3 g, so bones would lose calcium and muscles would atrophy; temperatures can dip below -87 degrees Celsius (or, -124.6 degrees Fahrenheit). Getting there would take 150-300 days unless the VASIMR plasma rocket is available by 2020.

4. Conversion to non-fossil fuels based energy infrastructure: see #1.

Alpha Centauri is 4.367 light years away, that's if we had a craft that could attain 99.9999% of c, the speed of light. It sounds ideal until you take into account the affects of time dilation: that would be roughly 3,088 years for any twins our astronauts had back on Earth. The "right stuff" would be similar to those embarking on Mars One - not just the vastness of space, but of time itself as a gulf.

That's also if there's a habitable but largely uninhabited planet around its twin or triple star system. It would take our Newtonian conventional rockets 165,000 years to reach it (75,000 by Dr. White's comparison to Voyager), enough time and 6,600 generations in the first case for our descendants to forget WHY they were sent there in the first place. If they survive at all, humanity would be decidedly different than the breed that left the cradle of Sol and Earth Millennium ago. What is now us, would be a distant or forgotten memory.

Whether eventually warp or non-causality impacting relativistic speeds, humanity will have to decide it wants to travel to another world, and try not to replicate the mistakes we've made on this one on the next.

IXS Enterprise and Alcubierre...

Do not go gentle into that good night,
Old age should burn and rave at close of day;
Rage, rage against the dying of the light.

Dylan Thomas, 1914 - 1953

The central theme of November's "Interstellar" and space exploration in particular...

If we even get 1/10 c (say, via a fusion or antimatter drive - more conceptual for physicists. I suspect the "exotic matter" as the star ship would require is possibly dark matter, and for now hard to define, find or manufacture). That technological leap will be for society energy-liberating, and we'd owe that to Dr. Miguel Alcubierre Moya (see link below).

Images sourced from: Daily Mail Online

Caption:
Pictured is an illustration of Dr White's IXS Enterprise, an interstellar ship drawn by artist Mark Rademaker that could be an accurate representation of what the first mission beyond the solar system will look like. The IXS Enterprise is a theory-fitting concept for a faster than light (FTL) ship.

#P4TC:
Miquel Alcubierre Moya
Speaking of Warp Drive

The EmDrive That Wasn't...

The EmDrive produces propulsion without propellant, according to its inventor. (Credit: SPR, Ltd)

Physicist John Baez has another, more colorful word to describe the spate of recent reports about a breakthrough space engine that produces thrust without any propellant. The word starts with “bull–.” I won’t finish it, this being a family-friendly web site and all. Baez himself has softened his tone and now calls it “baloney,” though his sentiment remains the same: The laws of physics remain intact, and the “impossible” space drive is, as far as anyone can tell, actually impossible.

The story begins several years back with a British inventor named Roger Shawyer and his EmDrive, a prototype rocket engine which he claimed generated thrust by bouncing microwaves around in an enclosed metal funnel. Since no mass or energy emerged from the engine, Shawyer’s claim was another way of saying that he’d found a way to violate the conservation of momentum. In Baez’s words, “this is about as plausible as powering a spaceship by having the crew push on it from the inside.” Shawyer argued that he was exploiting a loophole within general relativity. Baez calls his explanation “mumbo jumbo.”

I'd read about the EmDrive, and didn't blog about it, thankfully. Something about it didn't "smell right," and it put me in the mind of the whole "cold fusion" boondoggle of the late 80's - early 90's. Plus, I ran into some links that gave a "404" error, which if you're trying to convince someone to fund your project is probably not a good sell! Surprisingly, a few courageous ones are still doing work in the area. As my Air Force JROTC instructor was apt to say to disavow responsibility or knowledge in any subject: "not the kid!"

This is not to be confused with warp drive. That science is actually being done painstakingly, and the reporting as accurate as possible. Meaning: as science goes, one must report the failures as well as the successes and subject your study to ruthless peer review. It's the science equivalent of a gauntlet at a bar fight. Even 1/10th the speed of light would be a significant accomplishment, and get us to at least Alpha Centauri in a human lifetime. It would at least reduce Mars to a matter of minutes (I'll leave space tourism to the visionary).

The author, Corey S. Powell, ends his article with an appropriate Latin metaphor. The rest of the article is at the link below:

"Ad astra per aspera: through hardship, to the stars."

Discovery: Did NASA Validate an “Impossible” Space Drive? In a Word, No.
Cory S. Powell

Speaking of Warp Drive...

...whether or not we achieve it, it is fascinating that we're giving science discussions on it! Besides, this KILLS any previous designs of starships (without being too far off as well).

Instead of nacelles, it looks like we'd have two hoops enclosing the vessel. No "pivoting at Warp 2" recommended...see the video presentation below.

The dilemma can be summed in this humorous meme (not meant to insult anyone, but if you do a Google search, it's likely to come up):

Source: Motenes

The science behind the humor: it took about as much fuel as the shuttle weighed to get it into orbit. Fuel would then be spent (emptied), and Newtonian mechanics - momentum and gravitational pull of planets mostly - would be the predominate force moving a craft forward.

The only interstellar vehicle that's left our solar system is Voyager 1 on August 25, 2012, launched in 1977 when I was decidedly (blessedly) in high school. With abs...and hair on my head...

35 years is a long time for a one-way trip. NASA is attempting to reduce such journeys to a human lifetime, and maybe make it a round trip. Even 1/10 c (the speed of light) would be a civilization-changing accomplishment.

Look at the picture above. Nope, it’s not a snapshot of a Star Wars scene, or any other sci-fi movie. It’s what you get if you combine a NASA physicist working on achieving faster-than-light travel with a 3D artist, and the result is freaking AWESOME. And yes, you heard correctly, there are scientists working on faster-than-light travel, and this is what the ship could look like in the future.

Read more at http://www.iflscience.com/space/nasa-reveals-latest-warp-drive-ship-designs#EPvMa3eRlv4Ekmb1.99

#P4TC links:
"As Dreams Are Made On," September 21, 2012
"Alcubierre Drive," October 28, 2012
"Warp Fields and Research Efficacy," July 26, 2013

The Matter of Matter...

A faux historical account of Earth "pre-warp"

Warp drive, as enthusiastically a Trekkie I am, was a plot device created by Gene Roddenberry to get his astronauts from "here-to-there" in a reasonable amount of time to tell a story in an hour or less. NASA on the other hand, needs something other than chemical rockets that once the fuels expended to get the rocket into orbit - Newton's Laws dominate. Which is why currently a manned trip to Mars would take ~ 7 months to 300 days, and have astronauts with muscles of mush and bone mass of jello. VASIMR may get us there one day, thanks to the diligent research of people like Franklin Ramón Chang Díaz, PhD.

Abstract

The Alcubierre warp drive allows a spaceship to travel at an arbitrarily large global velocity by deforming the spacetime in a bubble around the spaceship. Little is known about the interactions between massive particles and the Alcubierre warp drive, or the effects of an accelerating or decelerating warp bubble. We examine geodesics representative of the paths of null and massive particles with a range of initial velocities from -c to c interacting with an Alcubierre warp bubble travelling at a range of globally subluminal and superluminal velocities on both constant and variable velocity paths. The key results for null particles match what would be expected of massive test particles as they approach +/- c. The increase in energy for massive and null particles is calculated in terms of v_s, the global ship velocity, and v_p, the initial velocity of the particle with respect to the rest frame of the origin/destination of the ship. Particles with positive v_p obtain extremely high energy and velocity and become "time locked" for the duration of their time in the bubble, experiencing very little proper time between entering and eventually leaving the bubble. When interacting with an accelerating bubble, any particles within the bubble at the time receive a velocity boost that increases or decreases the magnitude of their velocity if the particle is moving towards the front or rear of the bubble respectively. If the bubble is decelerating, the opposite effect is observed. Thus Eulerian matter is unaffected by bubble accelerations/decelerations. The magnitude of the velocity boosts scales with the magnitude of the bubble acceleration/deceleration.

As you read through the paper, please note the possibility of incinerating the star system/planet/people we'd be trying to hurry up and visit ("we come in peace" \\//_?).

I think - as even Star Trek alludes to - our first interstellar space faring will likely be at sub light speed in sleeper ships. Better to crawl first before running: 1/3 c to begin.

Someone will just have to invent inertial dampers since the Higgs Boson has been discovered so we don't kill ourselves or anyone else out there (another convenient plot device to avoid describing space faring humans as "street pizza" due to rapid acceleration).

In light of crawling, colonizing the moon, mining the asteroid belt and establishing a permanent base on Mars would be a good 1st start. Sagan mentioned terraforming the Red Planet or Venus in his book "The Cosmic Connection," which would be a practical solution on a global economy based on consumption. On the Kardashev scale, we are primitive.

Eventually, our toy/sandbox will be empty on the sandlot we're accustomed to playing in. Staying earthbound as a species will soon be the equivalent of not accepting potty training at the age and maturity one ought to be. Kind of gross, too.

Physics arXiv: The Alcubierre Warp Drive: On the Matter of Matter

Brendan McMonigal,∗ Geraint F. Lewis,† and Philip O’Byrne‡
Sydney Institute for Astronomy, School of Physics
A28, The University of Sydney, NSW 2006, Australia

Related:
Amazon: The Physics of Star Trek, Beyond Star Trek; Lawrence Krauss

Alcubierre Drive...

"… [it] is shown how, within the framework of general relativity and without the introduction of wormholes, it is possible to modify a spacetime in a way that allows a spaceship to travel with an arbitrarily large speed. By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible. The resulting distortion is reminiscent of the ‘warp drive’ of science fiction." (Alcubierre paper abstract)

By placing a spheroid object between two regions of space-time — one expanding, the other contracting — Alcubierre theorized you could create a “warp bubble” that moves space-time around the object, effectively re-positioning it. In essence, you’d have the end result of faster-than-light travel without the object itself having to move (with respect to its local frame of reference) at light-speed or faster.

The only catch: Alcubierre says that, “just as happens with wormholes,” you’d need “exotic matter” (matter with “strange properties”) to distort space-time. And the amount of energy necessary to power that would be on par with — wait for it — the mass-energy of the planet Jupiter.

So we’re back to “fuhgeddaboudit,” right?

Maybe not. According to NASA physicist Harold White, the energy problem may actually be surmountable by simply tweaking the warp drive’s geometry.

White, who just shared his latest ideas at the 100 Year Starship 2012 Public Symposium, says that if you adjust the shape of the ring surrounding the object, from something that looks like a flat halo into something thicker and curvier, you could power Alcubierre’s warp drive with a mass roughly the size of NASA’s Voyager 1 probe.

In other words: reduction in energy requirements from a planet with a mass equivalent to over 300 Earths, down to an object that weighs just under 1,600 pounds.

Time Tech: NASA Actually Working on Faster-than-Light Warp Drive

I'll Probably Hate Myself Later...

After all, Neutrinos have this little thing called "mass" (which, we don't quite know how much that is, mind you), it is > 0.

Lorentz Transformation for Mass

Do me and yourself a favor: 1 pound = 0.454 kilograms. Do that with your weight. I promise not to look.

Now make yourself travel at ~ 0.99c, plug it into your calculator and see what comes out. Even staying at one pound, the observed mass comes to ~ 3.21 kg. Mass, or "stuff" causes drag; slows everything, even a Neutrino -- down. For the case of v = c, your calculator would register an "error": division by zero yields infinite ( ∞ ) mass for any object, thereby needing infinite energy to propel any mass to the speed of light. Even that feat would require the literary invention of the Trek Inertial Damper.

Mind you, Special Relativity doesn't say a particle can't travel faster than light: like light always traveling at the speed of light and having no "mass"/inertia to drag it down (let mass_original for a photo = 0, because for photons: it does), tachyons would just always travel faster than light and have "imaginary rest mass" (like imaginary numbers, the error when you take the square root of -1). So...it gets a little strange, even to Einstein (the quote references a debate with Neils Bohr over Quantum Mechanics, that he ironically helped to create).

My advice: remain calm. These things kind of work themselves out in the long run.

1. Discovery magazine link (with some trepidation):
Rest Easy, Einstein -- Faster-Than-Light Neutrinos Would Not Violate Relativity
2. Neutrino Mass
3. Wikipedia: Neutrino