So, why aren't we travelling at light speed yet ?

[insane_alien]

then why don't orbiting neutron stars create a bubble around themselves?

 

i'd also be far more impressed if that picture wasn't to do with extrasolar planet detection. http://large.stanford.edu/courses/ph210/raman1/

 

any actual sources on slipstring drives?

[D H]

He gave one a while ago, the wikipedia page. The interesting thing about that page is the associated discussion page. The wiki editors are questioning the validity of the page. Should it stay (neat stuff) or should it go (pseudoscience). Per the discussion page, it's pseudoscience.

[Peron]

http://www.slipstring.com/

 

the slipstring drive is a book written by Andrew L Bender, in it he describes the drive that he invented.

Chapter 3

The Motions of Isolated Volumes of Spacetime or “SlipString Drive”

 

"Now that we have covered the basics of string theory, we can start to explore how to beat the system (or at least bend it a bit). Most theories of “faster-than-light” travel (that are based on sound scientific principles) involve wormholes, folding space, or other incredibly energy-intensive solutions. These theories often purport using a large percentage of the energy in the entire universe to create the wormhole or spatial fold..."

 

Chapter 3 begins by describing the difficulties with travel close to the speed of light, and possible mechanisms for these effects. It further illustrates why conventional methods will never be able to accelerate a ship close to the speed of light without serious drawbacks. This chapter also discusses fictional attempts at faster than light travel such as warp drive and why, unfortunately, they are highly unlikely to work. It also discusses recent theoretical scientific attempts at "faster than light" travel such as by using wormholes, spatial folds, and attempts such as those by Miguel Alcubierre whose negative quantum energy drive has been nicknamed "Warp Drive" by admiring fans. Additionally discussed are why all of the other methods have little chance of success on any practical sort of level in the near future to let us travel "faster than light."

 

It then enters the realm of practical “faster than light” travel by explaining how gravity waves work, and how they could be used to radically curve and “isolate” regions of spacetime from the rest of our universe. This could allow these isolated regions to move from one point in spacetime to another without actually passing through space! These regions can avoid all the problems described earlier, and their motion acts similarly to traveling through a wormhole. Illustrations assist you to understand how these regions are created and how they can effectively travel at incredible "faster than light" speeds without any ill-effects on the region's passengers. As with relativity, it is all about the point-of-view of the observer and the traveler, preserving physics as no matter actually passes through spacetime faster than light. This results in no alteration of the passage of time (or any paradoxes) even when travelling effectively "faster than light"!

 

Chapter 5

Exploration Opportunities Using SlipString Drive

 

"With a ship of this sort, intergalactic travel would no longer take so much time as to be impractical as it is today. Possibly we could travel from one solar system to the next in a matter of minutes. This way, we would be able to really explore our galaxy and our universe in person. We would no longer be limited to robotic probes and the Hubble Space Telescope, as wonderful and beautiful as the Hubble’s images and findings are..."

 

Chapter 5 describes what we could now accomplish with a SlipString Drive ship. Besides intergalactic travel, we could also protect the earth from comet collisions, and many other types threats to our planet. Eventually one of dozens of catastrophes could befall the earth, and this chapter discusses why and how humanity could avoid destruction from threats such as these. It also answers the questions: are there other beneficial, and even medical, uses of gravity waves?

Chapter 6

Gravity Waves and How to Create Them

 

"Gravity waves that we might be able to detect in the not-too-distant future are created in violent events such as supernovae and binary black holes that spiral in toward each other before one black hole gobbles up the other. These waves can travel across the universe, although detecting them over great distances becomes very difficult because these waves, as with gravity, get weaker according to the inverse square law..."

 

Chapter 6 describes gravity waves, how they are produced in nature, and how we could detect from orbit these large but distant waves. It then discusses how, once created by humans, gravity waves could be focused and manipulated in order to generate the forces needed to travel as described in Chapter 3.

 

[mooeypoo]

I think what we meant here when we asked for reference was a peer reviewed reference.

 

You know.. the type that is actually scientific, rather than science fiction'y.

[Peron]

There arn't any.

[D H]

There arn't any.

'Nuff said?

[Ranjha]

"It has been postulated that perhaps it is the process of accelaration that makes light speed impossible. If one can instantly travel at light speed (like a photon does) maybe one doesn't 'accumulate' infinite mass."------

This is the only valid point I could gather from all the verbage above. But there's a flaw in this statement also. Photon doesn't just choose to instantly travel at the light speed since it's actually a "REAL" particle like an electron which falls into a lower quantum state which releases this "energy". So you get light traveling at the speed of itself which is actually being caused by MASS.

[swansont]

@Peron: Still no math. Just some pictures and a few "It's highly theoretical"s

 

 

 

 

Entanglement: The Greatest Mystery in Physics

 

by Amir D. Aczel

 

Great read, can't put it down.

---

Merged post follows:

Consecutive posts merged

 

 

And this is superposition? But wouldn't you get it wrong and right every time? How would someone even determine the exact state of a quantum system in the first place?

 

In a nutshell how does quantum teleportation work?

 

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

[bascule]

I think a particularly interesting case for light-speed travel is the "Teleclone" machine given in the introduction of The Mind's I (written by philosopher Daniel Dennett):

 

http://themindi.blogspot.com/2007/02/introduction.html

 

Dennett proposes a mechanism for light speed travel: the Teleclone machine deconstructs your body, building a perfect map of the location of every particle. This blueprint for you is transmitted to another machine at the speed of light, which dutifully reassembles you according to the blueprint.

 

The Teleclone machine is given as a thought experiment in identity: if you stepped into the Teleclone, did you "die"? Is the clone of yourself assembled by the second machine really "you"? Or is it some doppleganger, and the "real" you is dead?

 

Regardless of your opinion on the identity problem, such a machine would, in effect, allow humans to travel at light speed, provided there's something on the other side of your journey to reassemble you.

[GDG]

I think a particularly interesting case for light-speed travel is the "Teleclone" machine given in the introduction of The Mind's I (written by philosopher Daniel Dennett):

 

http://themindi.blogspot.com/2007/02/introduction.html

 

Dennett proposes a mechanism for light speed travel: the Teleclone machine deconstructs your body, building a perfect map of the location of every particle. This blueprint for you is transmitted to another machine at the speed of light, which dutifully reassembles you according to the blueprint.

 

The Teleclone machine is given as a thought experiment in identity: if you stepped into the Teleclone, did you "die"? Is the clone of yourself assembled by the second machine really "you"? Or is it some doppleganger, and the "real" you is dead?

 

Regardless of your opinion on the identity problem, such a machine would, in effect, allow humans to travel at light speed, provided there's something on the other side of your journey to reassemble you.

 

Strictly a gedanken experiment: a machine cannot read the exact (to sub-angstrom accuracy) position of 2 x 10^27 atoms without violating the uncertainty principle, much less reassembling the exact same number of atoms in exactly the same positions. Hope you don't twitch during the scanning And then there's the data stream with absolutely no errors... Let's see, even if you could encode each atom (and you would need the atomic number and the absolute position) in just one bit, it would still take you 2 x 10^17 seconds to send the signal at 10 GHz. I think that works out to be something over 6 billion years, just to finish transmission. Hope you're not in a hurry

 

It is an interesting setup for philosophical debates though. And what happens when you accidentally press the "broadcast" button, and a copy of you steps out of each of multiple machines? (Aside from taking over the world, that is )

[mooeypoo]

It is an interesting setup for philosophical debates though. And what happens when you accidentally press the "broadcast" button, and a copy of you steps out of each of multiple machines? (Aside from taking over the world, that is )

 

<putting her nerd cap on>

 

Actually, Star Trek: TNG dealt with that possibility in the Episode "Second Chances", where Commander Riker found a copy of himself left behind on the surface of a planet after a transporter malfunction.

 

</nerd cap off>

 

Realistically? Who knows. Definitely not yet. Far far far not yet.

[bascule]

Strictly a gedanken experiment: a machine cannot read the exact (to sub-angstrom accuracy) position of 2 x 10^27 atoms without violating the uncertainty principle, much less reassembling the exact same number of atoms in exactly the same positions.

 

It doesn't need to be exact. Just "close enough," and generally cells are rather flexible as to how they're configured. We also have knowledge of how the cells are supposed to be arranged in the first place, so scanning errors can be corrected by fitting them to a computer model of cellular structure. There's a rather large margin for error, at least in the nanometer range.

 

And then there's the data stream with absolutely no errors...

 

This is what forward error correction and erasure coding are for.

 

Let's see, even if you could encode each atom (and you would need the atomic number and the absolute position) in just one bit, it would still take you 2 x 10^17 seconds to send the signal at 10 GHz. I think that works out to be something over 6 billion years, just to finish transmission. Hope you're not in a hurry

 

Not sure how you're doing your calculation. Let me do my own:

 

Humans are made out of redundant/self-similar structures. ~50 trillion cells, many of which contain nearly identical copies of the same organelles. For example, there's no need to individually represent each ribosome in the data stream, instead we can store the structure of a single ribosome and reproduce it everywhere ribosomes are found in our body.

 

Employing such methods of data compression I'm going to ballpark a human as approximately 1 exabyte of data. Applying immensely redundant forward error correction we'll take this up to 10 exabytes of data.

 

How about instead of 10 GHz we use a figure of 1 billion quadratures/symbols per second (i.e. 1 gigabaud). Employing quadrature amplitude modulation we could encode a large number of bits per quadrature using crazy future technologies. Let's go nuts and say 1 kilobit per quadrature. That alone is 1 terabyte every 8 seconds.

 

Now, let's employ multiplex mode transmission: one thousand simultaneous data streams. We're now at 1 exabyte per 8 seconds.

 

So, approximate time to transmit our compressed and erasure coded human signal over this crazy future data transmission apparatus: 80 seconds.

 

If you're beaming yourself back from Mars, of course, it will take 4 minutes for the radio/light beam to reach Earth.

 

Teleporting a human is not an insurmountable engineering challenge, although right now it probably seems as crazy as transmitting the entire contents of the Library of Alexandria 100 times over in less than a second would've seemed to the early Egyptians.

 

It is an interesting setup for philosophical debates though. And what happens when you accidentally press the "broadcast" button, and a copy of you steps out of each of multiple machines? (Aside from taking over the world, that is )

 

I invite you to read the linked chapter from the Mind's I where Dennett asks just this question:

 

http://themindi.blogspot.com/2007/02/introduction.html

[iNow]

It doesn't need to be exact. Just "close enough," and generally cells are rather flexible as to how they're configured. We also have knowledge of how the cells are supposed to be arranged in the first place, so scanning errors can be corrected by fitting them to a computer model of cellular structure. There's a rather large margin for error, at least in the nanometer range.

 

<...>

 

Humans are made out of redundant/self-similar structures.

I think many of these issues could be ameliorated using fractal geometry. Your mention of self-similar structures reminded me of this.

[Sisyphus]

It seems like pretty much any scifi that involves "teleporting" ends up raising those philosophical questions. Hell, even Star Trek does. Did Dennet imply it was his idea?

[bascule]

It seems like pretty much any scifi that involves "teleporting" ends up raising those philosophical questions. Hell, even Star Trek does. Did Dennet imply it was his idea?

 

God no, and the identity problem harkens all the way back to Aristotle and Locke.

[foodchain]

If the premise behind that "machine" were close to true none of the past or current problems with cloning animals should exist I would think. To do a copy and paste of a human being or slug with such data compression technologies would be tragic to say the least on the other side.

[purintjp]

I totally agree, Jill, but just to be pedantic, as we currently understand the cosmos, no mass can travel faster (or at) the speed of light.

 

 

And yet most scientists believe that entire galaxies can travel away faster

then light as long as they are "carried" along by the expansion of

space/time. It seems we just need something to "carry" us along to

achieve the same result. Who knows what that might be.

[JillSwift]

And yet most scientists believe that entire galaxies can travel away faster

then light as long as they are "carried" along by the expansion of

space/time. It seems we just need something to "carry" us along to

achieve the same result. Who knows what that might be.

Can you point to a source where scientists have ever published anything making that claim?

[purintjp]

I was under the impression that far distant galaxies are a lot farther away than can

be explained by the age of the universe. We are seeing only the light from the very

beginning of the universe of the galaxies farthest away. Who knows exactly where

they are now. If you look at my post in Cosmology and Astronomy 'Big Bang Paradox'

you will see Martin trying to explain it to me. Perhaps I misunderstood. If so, mea culpa.

[Mr Skeptic]

Can you point to a source where scientists have ever published anything making that claim?

 

More properly, "the distance between us and the galaxy is increasing faster than it would if the galaxy was traveling at the speed of light away from us". The galaxy is not really moving away from us, but rather space is expanding in between us.

[Janus]

It seems like pretty much any scifi that involves "teleporting" ends up raising those philosophical questions. Hell, even Star Trek does. Did Dennet imply it was his idea?

 

Frederik Pohl takes an interesting twist on on this in Wall Around a Star. In it, he uses tachyon transmission for teleporting over interstellar distances. The rub is that you only send a copy; the original stays home.

 

The moral dilemma comes in the fact that the copy can never return home, and in the story gets sent somewhere that is not too desirable to be. Thus when you use it, you are exiling a version of "you" to a distant world. Also, when the original steps into the device he does so with the expectation that he will just step back out without have gone anywhere, so the when the copy steps out of the other end with that same expectation, only to find himself on another world, it is quite a shock.

[D H]

I was under the impression that far distant galaxies are a lot farther away than can be explained by the age of the universe.

Not quite. The distant galaxies are a lot further further away than can be explained without considering the expansion of space. The recession rate of those very distant galaxies is greater than the speed of light, thanks to the expansion of space. So, to answer the question raised by the title of the thread: We are traveling at light speed, and then some -- with respect to those distant galaxies, that is. That of course does not answer the intent of the question.

 

The answer to the intent of the question is to stop reading so much science fiction and get a bit more down to Earth, or at least get a bit closer to the Milky Way.

[The Clairvoyant]

The answer to the intent of the question is to stop reading so much science fiction and get a bit more down to Earth, or at least get a bit closer to the Milky Way.

 

That's not answering the question, it's just giving advice (albeit poor advice seeing as a/ I hardly read any science fiction and b/ i'm as close to the milky way as you are ! )

 

To get to a stage where we eventually do travel at light speed what stages are needed 'on the way' to discovering how to do it ? What stage do you all think we're currently at ? Surely, scientists 'somewhere' are working on this project as this is surely the next big step for mankind ?

[purintjp]

I guess I was trying to make a point that it is possible to travel away from something faster than the speed of light if you are being "carried" rather then accelerating. It is pretty hard to wrap your mind around the difference.

As far as being closer to the Milky Way, I believe that practical infinity is easily less than a 1000 light years away and although I love all the gee-whiz stuff that comes out of scientific research I think it is probably a colossal waste of time to ascribe any sort of practical application or use in today's world. I think we would be better

served to allocate more money and time to Quantum Research as we are far more likely to reap any real world benefits. Of course, I am just and idiot without scientific credentials.

[D H]

Can you point to a source where scientists have ever published anything making that claim?

Davis, T.M. and Lineweaver, C.H. (2001), "Superluminal recession velocities", AIP Conf. Proc. 555, 348, DOI:10.1063/1.1363540 http://arxiv.org/abs/astro-ph/0011070

 

To get to a stage where we eventually do travel at light speed what stages are needed 'on the way' to discovering how to do it ? What stage do you all think we're currently at ? Surely, scientists 'somewhere' are working on this project as this is surely the next big step for mankind ?

What stage we're currently at: The state of the art is chemical propulsion. Mankind has a grand total of five tiny vehicles on escape trajectories from the solar system: Pioneer 10 and 11, Voyager 1 and 2, and New Horizons. The first four are well beyond any of the planets. New Horizons is en route to Pluto. That is the best we have done with, and is close to the best we can possibly do with chemical propulsion.

 

Beyond the state of the art: There's ion drive propulsion. Not much oomph, yet. Ion propulsion has moderately high specific impulse but incredibly low thrust. It took SMART-1 over a year to attain go from mid Earth orbit to lunar orbit. VASIMR has promise to bridge the gap between the high thrust / low impulse world of chemical rockets and the extremely low thrust / high impulse world of ion propulsion. Ion propulsion will not get us to the stars. Any kind of propulsion that requires the vehicle to carry the fuel with it will not get us to the stars. The non-relativistic Tsiolkovsky rocket equation is a very brutal equation. The relativistic rocket equation makes the Tsiolkovsky rocket equation look tame.

 

Propulsion that does not require carrying fuel with the vehicle is the realm science fiction. Solar sails have been tested on a very small and very limited scale. Bussard ram jets are science fiction, but plausible science fiction. Beyond that is science fantasy.