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[Cy83r]

Objection, 'classical' objects are a collection of almost innumerable quantum effects, the dissociation between physics and quantum physics is a failing of modern science.

[elizibar]

Objection, 'classical' objects are a collection of almost innumerable quantum effects, the dissociation between physics and quantum physics is a failing of modern science.

Let us perform a simple experiment to determine the probability of a classical-scale object quantum tunneling through another such object:

1) Smash head into keyboard.
2) Record whether the head tunneled through the keyboard.
3) Repeat the trial until a statistically significant number of events have occurred.

I'll be over here on the other side of the internet waiting for you to find your first positive tunneling event. Be sure to let me know, I could use a co-authorship on the publication of such a result!

[Razor One]

Elizibar, you owe me a new keyboard. And new nasal passages. I swear the bloody coke came out of my nose!





You don't understand quantum mechanics. I don't either, nor for that matter do experts in the field actually understand quantum mechanics.

Particles can tunnel through objects as a consequence of wave-particle duality. Heisenbergs uncertainty principle explains the phenomenon; it has a statistical probability of appearing on the other side of an object.

Classical objects, such as you, me, this can of coke, our erstwhile starship careering into a rogue asteroid and not quantum tunnelling their way through it are not individual particles. They cannot and can never exhibit wave-particle duality, therefore, heisenberg's uncertainty principle can never apply.

What do you mean by "The dissociation between physics and quantum physics" and how is that a failing of modern science?

And my question is, "so what?"

Just because it makes no sense doesn't necessarily mean anything at all (Hi quantum mechanics, you sick twisted hellscape you), other than that we're in for some seriously bonkers stuff. Is there some physical roadblock to causality violations (other than FTL seeming to be impossible)? Maybe we haven't observed paradoxes simply due to lack of contact with FTL capable civilizations? Maybe one day we'll colonize other solar systems before constructing the colony ships, but will that just be us scratching our heads or will the universe bear any effect from the paradox?

If I had to guess though it's a moot point and FTL is just not going to happen.

Here's a simple method to understand why causality is critical.

2H2 + O2 = 2H2O + Energy

That there is a chemical equation. It shows that when you add two hydrogen molecules (not atoms, molecules) and a molecule of oxygen, the result is two water molecules and energy.

The left side of the equation is the cause.
The right side of the equation is the effect.

Let's remove effect.

2H2 + O2 = ...

Oops. Water can't form. There goes life. The laws of chemistry are absolutely dependent on there being cause and effect. Cause and effect lead to a sequence of events that allow a chemical reaction to occur. Your body, right now, is absolutely dependent on millions of chemical reactions which allow you to live, breathe, percieve and think. If these chemical reactions occurred with no resultant effect, you would die, instantly. If the reactions occurred spontaneously within you without cause, you would also die. Instantly.

Put another way...

Science aims to model the universe. It does this through observation, hypotheses, modelling and experimentation.

Without causality, experimentation is pointless. Experimentation is pointless because one could not construct a model or formulate a hypothesis. One could do neither of these things because observations would never be consistent.

Our entire universe depends on the integrity of causality. It is present in everything from fundamental natural laws through to philosophy. We would not be able to exist if not for causality.

Chucking the book on causality is chucking the book on all existence.

Regarding the Mayan Calendar BS...

I've survived 17 seperate "End of the World!" claims. Earth's a tough old bitch and so am I apparently.

If someone claims they know the day and hour the Earth, or humanity at least, is going kaput, punch them. They're talking shit. They're either insane or trying to get money out of you. Potentially both.

and something that always bothered me with the 'no rest frame' is the speed of light....what exactly is it relative to? and that always makes me think of the speed of sound, there seems to be several similarities here, as you approach the 'barrier' you need more and more energy to overcome.....something in the way...the faster you go, the more wave front you are building up in front of you, creating drag hindering further acceleration...

so, my theory here is that the speed of light is merely the speed of sound in a near vacuum. now chew on that you damn physicists.

Physicists would love nothing more than to be able to go FTL without breaking causality or relativity. They'd be on the research gravy train for life if they could manage that... not to mention all the science groupies they could get

The speed of light in a vacuum, C, is a universal constant. It's not relative to anything as far as I know... perhaps the question there isn't worded properly.

Leaving that aside, I've explained it before. As you try to accelerate to C, the energy required to increase your velocity towards C increases exponentially. In order to attain C you need infinite energy. Infinite. More energy than the entire universe has. More energy than the entire (hypothetical) multiverse has. More energy than you can ever conceivably gather, more energy than can ever be gathered.

It is not possible to match C, let alone exceed it with relativity as it is currently.

That being said, it is possible to exceed the speed of light.

Just not in a vacuum.

In certain mediums, such as air, water, glass and the like, the speed of light actually slows down.

If you were to have a substance where the speed of light is 1 meter per second, you could concievably break the speed of light in that medium just by walking through it. They're called Bose-Einstein condensates. It still doesn't let you break C proper. Universal constants are finnicky like that.

Okay, my brains are starting to explode and these phantom spiders are starting to bite my hands. I've probably got a fair bit wrong but right now my brain needs a rest from the physics talk.

Until later

[dfacto]

Here's a simple method to understand why causality is critical.

2H2 + O2 = 2H2O + Energy

That there is a chemical equation. It shows that when you add two hydrogen molecules (not atoms, molecules) and a molecule of oxygen, the result is two water molecules and energy.

The left side of the equation is the cause.
The right side of the equation is the effect.

Let's remove effect.

2H2 + O2 = ...

Oops. Water can't form. There goes life. The laws of chemistry are absolutely dependent on there being cause and effect. Cause and effect lead to a sequence of events that allow a chemical reaction to occur. Your body, right now, is absolutely dependent on millions of chemical reactions which allow you to live, breathe, percieve and think. If these chemical reactions occurred with no resultant effect, you would die, instantly. If the reactions occurred spontaneously within you without cause, you would also die. Instantly.

Put another way...

Science aims to model the universe. It does this through observation, hypotheses, modelling and experimentation.

Without causality, experimentation is pointless. Experimentation is pointless because one could not construct a model or formulate a hypothesis. One could do neither of these things because observations would never be consistent.

Our entire universe depends on the integrity of causality. It is present in everything from fundamental natural laws through to philosophy. We would not be able to exist if not for causality.

Chucking the book on causality is chucking the book on all existence.

Not really. The universe is obviously causal (barring further physics asshattery), and I can't see why a single point causality violation would automatically negate all existence. It COULD, and causality violations could be a giant "off" switch on the whole operation, but on the other hand it might just be a localized quirk which only impedes physical processes in whatever space-time area it applies to. This is what my question basically is, and I'm pretty sure there's no answer: What does a single causality violation actually mean to the universe?

And now for a sci-fi tangent: causality violations would be the coolest weapon possible. You could cause any effect without requiring an apparent cause. Pair this with a quantum uncertainty luck device and you've got an invincible character.

[Mjolnir]

razor: E=mc2(yeah i know, can't be arsed figuring out how to do a squared 2) tells us that objects in motion have more energy, therefor a increase in energy without a increase in speed should be a increase in mass...these are still pretty small value changes though.

That's not what that equation means. For starters, there's no velocity in it. E = m*c^2 just expresses the equivalence relationship of energy and mass, with the conversion factor the square of the fastest possible relative velocity...c^2. That equation is specifically for the rest mass. The full equation is E^2 = (m*c^2)^2 + p^2*c^2, where p is momentum. Massive particles thus relate rest mass to energy as E = m*c^2, and massless particles like photons relate momentum to energy as E = p*c. For relativistic energy of moving massive particles, you use the whole thing, together with p = γ*m*v if you're working with velocity instead of momentum.

And the concept of relativistic mass has largely been abandoned by physics as being more misleading than useful. When modern physics speaks of mass, they mean the rest mass.

and something that always bothered me with the 'no rest frame' is the speed of light....what exactly is it relative to?

It's not relative to anything. The speed of light in vacuum is always c with respect to the observer. Even if you have multiple observers flying around and flashing lights at each other. c is invariant, lengths and time are not.

and that always makes me think of the speed of sound, there seems to be several similarities here, as you approach the 'barrier' you need more and more energy to overcome.....something in the way...the faster you go, the more wave front you are building up in front of you, creating drag hindering further acceleration...

There's only a very superficial resemblance to drag. There's nothing slowing things down toward some special rest state, and nothing taking energy away from relativistic particles undergoing acceleration...they retain all the kinetic energy added to them. It's not drag, it's geometry, in a non-Euclidian spacetime:
http://en.wikipedia.org/wiki/Minkowski_space

so, my theory here is that the speed of light is merely the speed of sound in a near vacuum. now chew on that you damn physicists.

How can a vacuum with particles averaging a centimeter or so of spacing so effectively propagate waves with wavelengths of a few hundred nanometers? Why isn't vision hopelessly blurred in a near-vacuum due to lack of particles to carry a clear image?

[Mjolnir]

As for quantum tunneling, it does not transmit information faster than light. It is in part a product of our thinking of particles as being little balls with distinct locations and velocities, when they often behave as probability waveforms. Essentially, the waveform of a particle with its mean position right up against a barrier can extend across that barrier, giving it a nonzero probability of interacting with things on the far side and itself moving past a barrier that in classical mechanics would be impassable.

There's not been so much as a hint of an effect that would let us tunnel even elementary particles across macroscopic distances, or anything that would let us use it for FTL communications. Tunneling is pretty well understood, it's the operating principle of several electronic and optical devices and a major obstacle in others. It's just not applicable to sending messages, let alone travel.

Asimov wrote a good story once dealing with cause and effect. I can't recall the name of the story but it relied on a chemical reaction. It was argued that if timed just right, a certain substance would dissolve in water before it actually touched it. When they tried to break causality by preventing the substance from actually dissolving in water, they faced all kinds of natural disasters and deleterious effects until they finally dunked the substance in water.

"The Endochronic Properties of Resublimated Thiotimoline"
http://en.wikipedia.org/wiki/Thiotimoline

[Cy83r]

Objection, 'classical' objects are a collection of almost innumerable quantum effects, the dissociation between physics and quantum physics is a failing of modern science.

Let us perform a simple experiment to determine the probability of a classical-scale object quantum tunneling through another such object:

1) Smash head into keyboard.
2) Record whether the head tunneled through the keyboard.
3) Repeat the trial until a statistically significant number of events have occurred.

I'll be over here on the other side of the internet waiting for you to find your first positive tunneling event. Be sure to let me know, I could use a co-authorship on the publication of such a result!

Statement, quantum tunneling of any scale only requires the proper amount of energy, you are neglecting that the hypothetical classical tunneling event I posited occurs to an object moving above the lightspeed barrier, there may be sufficient energy to cause quantum tunneling of a sufficient majority if not the entirety of such an object just as there may be enough energy to escape the event horizon of a black hole.

What do you mean by "The dissociation between physics and quantum physics" and how is that a failing of modern science?

No working unified theory. If the universe works the way we think it ought to, there is a unified physical theory.

2H2 + O2 = 2H2O + Energy

Energy + 2h2o = 2h2 + o2

All good equations reciprocate and that is less cause and effect that a bureaucratic shuffling of papers. IIRC a proper cause and effect is something that is more or less irreversible by any account of physics, things do not fall upwards unless launched, a shattered glass does not unbreak except in an art film, dead bodies do not spontaneously come back to life except in horror and fantasy films. Time travel and all of the funny conundrums it raises are cute, but the more I think about it, the notions it has spawned seem patently ridiculous.

What I find most amusing is, however, that you claim 'exceeding the c barrier causes time travel' and then say 'because time travel is patently ridiculous, exceeding the c barrier is impossible'. I am still challenging the validity of the first claim, not the second.

And as I understand it, light only slows in a medium because it is being absorbed and emitted by the particles it impacts, so it isn't really slowing down, just jumping around rather than taking the arrow's path. You could argue that the speed of everything slows down when it encounters an intervening medium... so... yeah.

[Razor One]

What I find most amusing is, however, that you claim 'exceeding the c barrier causes time travel'

Work ran late, I have Kendo in the morning tom- today, so I'll only answer this portion for now.

FTL, Causality, Relativity.

Pick two.

In the scenario where we toss causality, we have FTL and Relativity.

FTL = Time travel due to relativity. Because no point in reality is objective but relative, if you should exceed the speed of light at any point, you will appear to an observer somewhere in the universe to be travelling backwards in time.

If you like causality and FTL, then Relativity needs to be junked. This is possible to do by using special reference frames.

Unless you postulate that we should be chucking Relativity out the window in addition to causality, in which case, why not just write physics and science in general off as a bad idea?

...and then say 'because time travel is patently ridiculous, exceeding the c barrier is impossible'.

Perhaps it's just me being tired but... where exactly did I say this?

[Cy83r]

IMPLICATIONS

Also, you take Kendo classes? You win.

But no, seriously, how the hell do you watch someone travel back in time? My brain is running up against a wall here trying to imagine what negative time looks like. Everybody says, oh well neg time is time travel, but why? Is it just because we have so many stories that that's the first thing we think of. Somebody please tell me where the math says negative time is traveling into the past because I can't read the math.

But wait, hang on a second, what if negative time is impossible, like negative mass, it would then be imaginary time, right? And what does that look like?

And relativity itself is hard for me to conceptualize, being an amoral objectivist (that is objectivism without Ayn's moral bull) and a nihilist, idealist, utilitarian, determinist, and masochistic hedonist among other collections of contradictions. I accept that perception can be relative, but I rail against the idea that this phenomenon carries over to the physical execution of events. The math may allow it, but the math has allowed falsities before, and this seems to my perception and understanding to be wrong. Not only is my intuition screaming in protest, a bad gauge of the weather itself, but examples given do not seem to follow relativity in their explanations.

For instance, in the argument about the two duelists striking each other before they even shoot, both duelists moved under propulsion before observing their time and then firing. To my understanding this is a completely invalid example of relativity in action and would not result in the proposed outcome for the obvious reason that both induce upon themselves a new velocity at the start of the duel and thus are both said to be in movement and that neither can be said to be able to claim the state of being at rest relative to the other.

[junk]

IMPLICATIONS

Also, you take Kendo classes? You win.

But no, seriously, how the hell do you watch someone travel back in time? My brain is running up against a wall here trying to imagine what negative time looks like. Everybody says, oh well neg time is time travel, but why? Is it just because we have so many stories that that's the first thing we think of. Somebody please tell me where the math says negative time is traveling into the past because I can't read the math.

But wait, hang on a second, what if negative time is impossible, like negative mass, it would then be imaginary time, right? And what does that look like?

And relativity itself is hard for me to conceptualize, being an amoral objectivist (that is objectivism without Ayn's moral bull) and a nihilist, idealist, utilitarian, determinist, and masochistic hedonist among other collections of contradictions. I accept that perception can be relative, but I rail against the idea that this phenomenon carries over to the physical execution of events. The math may allow it, but the math has allowed falsities before, and this seems to my perception and understanding to be wrong. Not only is my intuition screaming in protest, a bad gauge of the weather itself, but examples given do not seem to follow relativity in their explanations.

For instance, in the argument about the two duelists striking each other before they even shoot, both duelists moved under propulsion before observing their time and then firing. To my understanding this is a completely invalid example of relativity in action and would not result in the proposed outcome for the obvious reason that both induce upon themselves a new velocity at the start of the duel and thus are both said to be in movement and that neither can be said to be able to claim the state of being at rest relative to the other.

Unless I'm mistaken they've tested time dilatation recently and it does actually happen

[Nemo]

They've tested time dilation multiple times. It works.
http://en.wikipedia.org/wiki/Time_dilat ... tion_tests

You're hanging up on negative time, there is no negative time. Ignore time for a minute, think of physical space. When you go "up" you have a positive velocity, "down" is also movement with a positive velocity, "left & right" both positive movement, "ah ha! forwards and back!" newp still positive movement both ways. There is no negative movement, just velocities in different directions, and always forwards. Similar thing with time. The human mind thinks of time as a set of train rails with "future" and "past" owing to the way our memory works, but that's not reality. One moves through time just as one moves through space, one moves through space just as one moves through time.


Lets change the 'tachyon' pistol duel, because, honestly, pistol duels? Who does that anymore? Two starships start at point A and travel in perfectly opposite directions. Starship 1 and 2 both accelerate to .999...c and hold course and speed for 1 minute. Each fires their FTL 'tachyon' pulse cannons directly aft, targeting the other ship. Each ship scores a hit on the other ship before they fire their weapons. Say whu? With time dilation aboard ship 1, ship 2 doesn't have the time to get up to speed. With the dilation aboard ship 2, ship 1 never got up to speed. Since both ships are hit and destroyed before they fired, neither ship fires. Since neither ship fires both ships fire.... Say Whu? Causality has been seriously mangled.

As far as I know, for FTL to work there has to be some external force connecting separate reference frames so that causality is maintained. We don't see that. We're stuck slowboating.

[icekatze]

hi hi

In Outsider, the problems associated with FTL travel are somewhat mitigated by circumstance. Ships are limited in how far back in time they can travel due to the velocities and distances involved. Nobody is jumping across the universe, and nobody is getting up to highly relativistic speeds during the jump process, so time dilation isn't as bad as it could be.

Still, you could set up two ships in two nearby systems, have one jump over to the next system with a message, transmit the message to the second ship just before it jumps back to the first system. That would get you some time travel, but the transit time in physical space required for a successful jump makes doing this process indefinitely a difficult proposition. So you're still going to be limited by the first point.

There may also be some temporary warping of hyperspace that occurs when a ship makes a hyperspace jump that could dilate return jumps further into the future than they might otherwise be. Not a universal frame of reference, but more like a temporary local pseudo-frame-of-reference.

[Mjolnir]

But no, seriously, how the hell do you watch someone travel back in time? My brain is running up against a wall here trying to imagine what negative time looks like. Everybody says, oh well neg time is time travel, but why? Is it just because we have so many stories that that's the first thing we think of. Somebody please tell me where the math says negative time is traveling into the past because I can't read the math.

It isn't an issue at all if FTL phenomena don't exist.

And relativity itself is hard for me to conceptualize, being an amoral objectivist (that is objectivism without Ayn's moral bull) and a nihilist, idealist, utilitarian, determinist, and masochistic hedonist among other collections of contradictions. I accept that perception can be relative, but I rail against the idea that this phenomenon carries over to the physical execution of events. The math may allow it, but the math has allowed falsities before, and this seems to my perception and understanding to be wrong. Not only is my intuition screaming in protest, a bad gauge of the weather itself, but examples given do not seem to follow relativity in their explanations.

Again, time dilation is measured fact, an effect that commonly has to be taken into account for modern time and navigation systems. It's not a perceptual effect, it's not an illusion. Clocks taking different paths do in fact experience different amounts of time before meeting again. The difference is predictable by the math of relativity and repeatably measurable by experiment.

For instance, in the argument about the two duelists striking each other before they even shoot, both duelists moved under propulsion before observing their time and then firing. To my understanding this is a completely invalid example of relativity in action

It's perfectly valid, up to the point where a FTL signal is involved, such signals being considered nonsensical in relativity. It's an illustration of how FTL signaling or travel doesn't make sense. The nonsensical results aren't a flaw in the argument, they are the whole point of the argument.

and would not result in the proposed outcome for the obvious reason that both induce upon themselves a new velocity at the start of the duel and thus are both said to be in movement and that neither can be said to be able to claim the state of being at rest relative to the other.

Each sees themselves as being at rest, with the other moving. Every observer in an inertial frame can consider themselves to be at rest. It does not matter how they might have accelerated from some arbitrary reference point.

[Cy83r]

They've tested time dilation multiple times. It works.

Never said it didn't.

Lets change the 'tachyon' pistol duel, because, honestly, pistol duels?

'tachyon' pistol duel

'tachyon'

'tachyon'

'tachyon'

'tachyon'

Ah, I see what I missed now.

However, if both parties are experiencing roughly the same rate of dilation then... aren't they still reacting at the same speed and thus hit each other at roughly the same rate of delay? After all, the article said, IIRC, they were hitting each other instantly after firing, but FTL does not necessarily imply instant transmission from point to point, just that the transmission is faster than the propagation of light, like some sort of very odd hypersonic boom mixed with a doppler effect.

Actually, this is very much like hypersonic objects, targets are being hit by hyperlight particles, which means that they are hit before they would ever have a chance to register to oncoming object let alone the actions leading up to whatever launched said HL object at them. Even if time is wonkified according to the HL object, this effect would only occur according to the HL object, observers still react normally between the firing and being hit, time will pass forwards and the HLO will arrive sometime after, even a tiny fraction of sometime, being launched. If anything, the target suffering from heavy time dilation is only hit faster than one in a state of lower dilation and a firer in a high dilation state only sees the impact result faster. None of this implies that the effect would occur in an instant nor does it imply that some combination of of high dilation actor and HLO induces the HLO to break causality. It all just happens really really fast from the HDA's perspective and since it is an HLO it all happens really really fast from anyone's perspective (because, let's face it, in the grand scheme of things, light is really freaking slow).

[Mjolnir]

However, if both parties are experiencing roughly the same rate of dilation then... aren't they still reacting at the same speed and thus hit each other at roughly the same rate of delay?

You're thinking about the setup like they're actually moving at some definite velocity with respect to a fixed rest frame. There's no fixed rest frame.

After all, the article said, IIRC, they were hitting each other instantly after firing, but FTL does not necessarily imply instant transmission from point to point, just that the transmission is faster than the propagation of light, like some sort of very odd hypersonic boom mixed with a doppler effect.

That is only to simplify things a bit. Non-instantaneous FTL signaling is equivalent to signaling limited by the speed of light for a distance followed by instantaneous signaling.

Actually, this is very much like hypersonic objects, targets are being hit by hyperlight particles, which means that they are hit before they would ever have a chance to register to oncoming object let alone the actions leading up to whatever launched said HL object at them. Even if time is wonkified according to the HL object, this effect would only occur according to the HL object, observers still react normally between the firing and being hit, time will pass forwards and the HLO will arrive sometime after, even a tiny fraction of sometime, being launched. If anything, the target suffering from heavy time dilation is only hit faster than one in a state of lower dilation and a firer in a high dilation state only sees the impact result faster. None of this implies that the effect would occur in an instant nor does it imply that some combination of of high dilation actor and HLO induces the HLO to break causality. It all just happens really really fast from the HDA's perspective and since it is an HLO it all happens really really fast from anyone's perspective (because, let's face it, in the grand scheme of things, light is really freaking slow).

Again, you're assuming a fixed rest frame, with a universal clock that time dilation is measured in reference to. Relativity doesn't work that way.

[icekatze]

hi hi

Simply put, from the perspective of both duelists, time for their opponent is moving slower than it is for themselves. This is not a paradox -at least it isn't up until the point where you go faster than light.

graphical explanation

[Cy83r]

Simply put, from the perspective of both duelists, time for their opponent is moving slower than it is for themselves.

Wait, no, that can't be right, from the perspective of someone at a high time dilation, everything else moves faster... doesn't it?

[Mjolnir]

Simply put, from the perspective of both duelists, time for their opponent is moving slower than it is for themselves.

Wait, no, that can't be right, from the perspective of someone at a high time dilation, everything else moves faster... doesn't it?

No. Leaving out the complexities of GR and gravitational time dilation, time dilation isn't absolutely high or low, it is a function of relative motion between observers. Events in another frame can appear to move faster than normal, but this is a result of doppler effects, not time dilation...time dilation always means clocks in the other frame run slower.

[Nemo]

They've tested time dilation multiple times. It works.

Never said it didn't.

That part was for junk. Left out mah quotes.

[Cy83r]

Simply put, from the perspective of both duelists, time for their opponent is moving slower than it is for themselves.

Wait, no, that can't be right, from the perspective of someone at a high time dilation, everything else moves faster... doesn't it?

No. Leaving out the complexities of GR and gravitational time dilation, time dilation isn't absolutely high or low, it is a function of relative motion between observers. Events in another frame can appear to move faster than normal, but this is a result of doppler effects, not time dilation...time dilation always means clocks in the other frame run slower.

...wait, time dilation is a function of acceleration, correct? What happens when a ship stops accelerating? No, that can't be right, the potential energy is still there so you'd still be under the effect, or at least you should. Fuck it, I don't understand these physics anymore.