# Gravity Works Like This

When you speak of an object not moving for a duration, how has the observer experienced or referenced that duration without any motion (macro, molecular, atomic)? The common mistake is to forget the experience of time or the reference to a change of time (like a clock) requires motion.

Empirically change requires motion, hence a change in time requires motion. It is common and intuitive to think of time as changing, being separate and void of motion but nothing can be observed to change physically without a change in position (motion/time are the same). That is why time is said to have come into existence at the big bang, in a singularity there is no space (separation) in which to calculate a change in position (motion), therefore no way to calculate time which is the same and coincident. Time can only be observed empirically when there is some increment of space to account for a change in position.

When you get your head around that, the coupling of space and time is as obvious as any axiom can be, space (separation) requires the ability to change position to have any meaning, and the ability to change position requires space.
Good stuff Maxila. Hence time travel is science fiction.

Time travel as per the twin paradox [which isn't a paradox] is possible, and has been achieved many times with sub atomic and other inert particles.
If we could one day achieve relativistic speeds, or perceived relativistic speeds like the Alcubierre drive, then time travel at least to the future is possible.

Actually, time travel is science friction, but that isn't important right now.

Actually, time travel is science friction, but that isn't important right now.

Well it is seen with muons for instance, and as I say, "as per the twin paradox" not anything like that which Rod Taylor did in the movie "tHE tIME tRAVELLER"

Time travel as per the twin paradox [which isn't a paradox] is possible, and has been achieved many times with sub atomic and other inert particles.
If we could one day achieve relativistic speeds, or perceived relativistic speeds like the Alcubierre drive, then time travel at least to the future is possible.

You are correct. It is impossible for anything NOT to travel forward through time. The experienced rate of travel is affected by speed and acceleration, time dilating to a slower rate with increasing energy. It is not possible to travel backward through time(the past no longer exists, there is no place to travel to). Everything(the whole Universe)travels forward through time at the rate determined by the energy of local spacetime. The rates are all Relative to speed and acceleration. Time travel is actually a requirement of spacetime, even if you slow your own personal experienced time to a stop(by speed or acceleration), you still travel forward in time.

Grumpy

So did you understand where your own assumptions and beliefs on which you based your criticism of Maxila was a 'fallacious' purely NON-physical philosophical base ONLY?

Actually, yes I do. A while ago I got the pleasure of reading through Maxwell's "Matter and Motion" and he lays out pretty much what I did there, explicitly noting that questions of space, time and movement were all linked together by a specific Set of related assumptions. He also notes that without these assumptions, one is unable to do physics. So he suggests that, until people can do better, we all accept that these assumptions are a part of physics.

Einstein actually did better: he replaced those assumptions with slightly different ones and he and others were able to show that we could do physics better (on a number of pragmatic grounds, including accuracy) with the new assumptions.

If someone wants to do away with time and replace it with motion, then they are free to do so if they can demonstrate that they can do the work of physics with those applications.

It's a common mistake of people who do not actually do science or philosophy to think that they have discovered something deep when they discover the connection between motion and time. I wish these people would simply stick to doing drugs for their head rush.

I haven't discovered anything, I have simply stated empirical facts (testable and verifiable). It is also common for people to ignore and rationalize away facts in order to justify existing beliefs, whether they be defending the bible, or science, that human nature is unchanged. I won't waste much time arguing with someone who continually rationalizes their thoughts as they wish, even when they are in contradiction to empirical, observable facts. Ignoring facts in defense of your beliefs is not science it is faith.

I haven't discovered anything,
I'll agree to that.

I have simply stated empirical facts (testable and verifiable).
Well, no. You have made claims about the constant relationship between the ability to observe time passing and some kind of motion. This is not an observation, this is a theoretical claim. Someone sitting in a room where there is no motion may pass for a while noticing the passage of time but not any motion; it is our theoretical commitment to the motion in their brain and body that allows this to not count as a counter-example to your claim.

It is also common for people to ignore and rationalize away facts in order to justify existing beliefs, whether they be defending the bible, or science, that human nature is unchanged. I won't waste much time arguing with someone who continually rationalizes their thoughts as they wish, even when they are in contradiction to empirical, observable facts. Ignoring facts in defense of your beliefs is not science it is faith.
Oh, wait, you think that you are talking about me, when it is you ignoring the fact that there is no actually performed science of physics where one can just have movement without time.

Actually, time travel is science friction, but that isn't important right now.

Time travel in relativity theory is traveling into the future of a different proper frame of reference. For example: For the relativistic rocket, constant acceleration g_earth, the prediction for proper time in the rocket frame is 28 earth years to Andromeda. The prediction for the proper frame of the earth is 2,000,000 earth year to Andromeda. The distance in the rocket proper frame is 28 light years and 2,000,000 light years in earth's proper frame.

So the tick ratio

dTau_rocket/dTau_earth = 28_earth year/2,000,000_earth year = 1.4E-15.

Theoretically the rocket could return to earth 4,000,000 years later than when they left. It's happening 'every tick' between the GPS satellite and earth based clocks. On an infinitesimal scale. Time travel in your own proper frame is what's impossible.

This is a cool formula you can derive from the Schwarzschild metric which I like to call a relativistic time travel equation. Just for the fun of it. This is for an orbit and both the SR and GR relativistic time dilation are included in the derivation.

Problem 7, page 4-32, Exploring Black Holes.\

The derivation

Put the derivative of the effective potential term (from the equation of motion) into quadratic form (to find critical values)

r*^2 - L*^2r + 3L*^2 = 0

Where

r* = r/M, and L* = L/mM

Then divide through by L*^2 and manipulate to get

r*^2/L*^2 = r* - 3 [saving this for a later
substitution]

Setting dr = 0 in the Schwarzchild metric and
substituting dphi = (L*/r*^2)dTau the metric becomes

dTau^2 = (1 - 2/r*)dt^2 - (L*^2/r*^2)dTau^2

To find the ratio dTau^2/dt^2 divide through by the
bookkeeper time dt^2 and simplify to

(dTau/dt)^2 = (1 - 2/r*) / (1 + L*^2/r*^2)

Now substitute 1/(r*-3) for L*^2/r*^2 and simplify to

dTau/dt = (1 - 3M/r)^1/2

This following example uses the time travel equation in a way which might be interesting to you. Note that the time intervals dTau and dt are different but that they both measure time intervals as recorded by a clock in a specific coordinate system. dt for Earth and dTau for the spaceship orbiting the black hole.

Abe signs on with the crew of 'Warp Drive 1' while Bill remains on Earth. Warp Drive 1's maiden voyage is to visit a solar mass (M = 1477 meters) black hole, free fall to a knife edge orbit just outside the photon sphere at r = 3.000001M, remain in orbit for 172,800 seconds (Two Earth days) wristwatch time (dTau), and then return to Earth arriving ~ 9.5 years in Earths future. During the warp phase of the journey the ship remains in an inertial rest frame so the difference in wristwatch rate for Abe and Bill is minimal during this phase of the journey.

What will be the difference in elapsed wristwatch time, dTau, for Abe with respect to the elapsed coordinate time, dt, for
Bill when they meet upon Abe's return? Keeping in mind that dTau is measured with Abe's wristwatch (shipframe) and the wristwatch time for
Bill is measured with Bill's wristwatch (Earthframe).

From the Schwarzchild geometry a time travel equation

dTau/dt = (1-3M/r)^1/2

Substituting 172,800 seconds for dTau, 3.000001M for r, and 1477 meter for M, then solving for dt

dt = 172,800s / 5.7735x10-4 = 299298529.2s

Since there are 3.156x107 seconds / Earth year

299298529.2 seconds / 3.156x107 seconds / Earth year
= ~ 9.48 Earth year

When Abe returns the twins can determine whether the prediction was correct by just comparing clocks.

So you might play with this in the weak field. Set r for an orbit around the Sun. This equation includes the gravitational and SR component of time dilation.

dTau/dt = (1-3M/r)^1/2

PhysBang

Oh, wait, you think that you are talking about me, when it is you ignoring the fact that there is no actually performed science of physics where one can just have movement without time.

You cannot even describe a single event, much less a series of events that we call movement, without designating a point in time in the description. When someone says they saw an explosion, for example, you can look all you like at that point in space but unless you did so at the exact moment when the explosion occurred you will not see that event. IE there can be no event without a time to occur within. There is no way to describe an event without including a specific time or series of times(as well as locations in space). The time is the stage upon which events occur, it is in no way inhibited by anyone's inability to measure it(which is all movement does, give you a means to measure it).

brucep

Time travel in your own proper frame is what's impossible.

Rather, the time travel rate(into the future)is invariant to you within your own frame. You will always see your own rate of travel into the future as being the same, as will all clocks that are within that frame. That is an actual physical property. All frames see themselves as the "normal" ones, everyone else's frame is the one that looks dilated.

Grumpy

I think this person makes some valid points:
And don't tell me that knowledge is "subjective". Knowledge has to be represented in a brain, and that makes it as physical as anything else. For M to physically represent an accurate picture of the state of Y, M's physical state must correlate with the state of Y. You can take thermodynamic advantage of that - it's called a Szilard engine.

Or as E.T. Jaynes put it, "The old adage 'knowledge is power' is a very cogent truth, both in human relations and in thermodynamics."

And conversely, one subsystem cannot increase in mutual information with another subsystem, without (a) interacting with it and (b) doing thermodynamic work.

Otherwise you could build a Maxwell's Demon and violate the Second Law of Thermodynamics - which in turn would violate Liouville's Theorem - which is prohibited in the standard model of physics.

Which is to say: To form accurate beliefs about something, you really do have to observe it. It's a very physical, very real process: any rational mind does "work" in the thermodynamic sense, not just the sense of mental effort.

(It is sometimes said that it is erasing bits in order to prepare for the next observation that takes the thermodynamic work - but that distinction is just a matter of words and perspective; the math is unambiguous.)

(Discovering logical "truths" is a complication which I will not, for now, consider - at least in part because I am still thinking through the exact formalism myself. In thermodynamics, knowledge of logical truths does not count as negentropy; as would be expected, since a reversible computer can compute logical truths at arbitrarily low cost. All this that I have said is true of the logically omniscient: any lesser mind will necessarily be less efficient.)

"Forming accurate beliefs requires a corresponding amount of evidence" is a very cogent truth both in human relations and in thermodynamics: if blind faith actually worked as a method of investigation, you could turn warm water into electricity and ice cubes. Just build a Maxwell's Demon that has blind faith in molecule velocities.

Engines of cognition are not so different from heat engines, though they manipulate entropy in a more subtle form than burning gasoline. For example, to the extent that an engine of cognition is not perfectly efficient, it must radiate waste heat, just like a car engine or refrigerator.

"Cold rationality" is true in a sense that Hollywood scriptwriters never dreamed (and false in the sense that they did dream).

So unless you can tell me which specific step in your argument violates the laws of physics by giving you true knowledge of the unseen, don't expect me to believe that a big, elaborate clever argument can do it either
http://lesswrong.com/lw/o5/the_second_law_of_thermodynamics_and_engines_of/

brucep said:
Time travel in your own proper frame is what's impossible.
The speed of light is constant; you can't change it by moving "away from" your own frame of reference.

You are correct. It is impossible for anything NOT to travel forward through time. The experienced rate of travel is affected by speed and acceleration, time dilating to a slower rate with increasing energy. It is not possible to travel backward through time(the past no longer exists, there is no place to travel to). Everything(the whole Universe)travels forward through time at the rate determined by the energy of local spacetime. The rates are all Relative to speed and acceleration. Time travel is actually a requirement of spacetime, even if you slow your own personal experienced time to a stop(by speed or acceleration), you still travel forward in time.

Grumpy

BINGO!!!
Thanks Grumps!

I think this person makes some valid points:http://lesswrong.com/lw/o5/the_second_law_of_thermodynamics_and_engines_of/

The speed of light is constant; you can't change it by moving "away from" your own frame of reference.

Nobody is changing the local measurement of the speed of light. What I showed you is a comparison of the rocket clock with a clock on earth [using relativity theory to make the predictions]. Both are measured in the local proper frame where the clock resides. All measurement of the local speed of light in the Rocket frame will be invariant c [for example: set up an experiment to measure the local speed of light inside the ship during the journey]. Earth measures the distance to Andromeda as 2,000,000 light years. Over it's path the rocket measures the distance to Andromeda as ~ 28 light years. A little further because the rocket can never reach c. The path of the rocket to Andromeda and back to earth is equivalent to the Twin Paradox. The time dilation is associated with the change in instantaneous speed over the Rockets g_earth acceleration from the beginning to the end of the journey. Time dilation is not associated with acceleration. The measurement of time and length in the rocket proper frame are invariant. The measurement of time and length on the earth are invariant. Relativity predicts both the distance and time measured in the proper frame are invariant. When the ship returns to earth ~ 56 years have elapsed in the Rocket proper frame and 4,000,000 years have elapsed on Earth. The GPS proofs this. That's why it's an important test for relativity theory [GR]. The GPS satellite clock and the earth clock are the twins.

Good morning, Grumpy.

You are correct. It is impossible for anything NOT to travel forward through time. The experienced rate of travel is affected by speed and acceleration, time dilating to a slower rate with increasing energy. It is not possible to travel backward through time(the past no longer exists, there is no place to travel to). Everything(the whole Universe)travels forward through time at the rate determined by the energy of local spacetime. The rates are all Relative to speed and acceleration. Time travel is actually a requirement of spacetime, even if you slow your own personal experienced time to a stop(by speed or acceleration), you still travel forward in time.

Grumpy
Careful, mate. The 'spaceTIME' construct is an ABSTRACTION not the REAL THING in which things 'happen/move'. Here is Einstein again on the express approach/method OF 'abstraction' from reality and effectively leaving the mechanistic etc properties/entities/processes 'behind' in the math analysis/modeling approach they took back then...
More careful reflection teaches us, however, that the special theory of relativity does not compel us to deny ether. We may assume the existence of an ether; only we must give up ascribing a definite state of motion to it, i.e. we must by abstraction take from it the last mechanical characteristic which Lorentz had still left it. We shall see later that this point of view, the conceivability of which I shall at once endeavour to make more intelligible by a somewhat halting comparison, is justified by the results of the general theory of relativity.----Einstein

So any 'travel' in the purely MATH ABSTRACTION 'construct' of 'spaceTIME' is pure fantasy abstraction as well....NOT reality at all. Since you can't 'travel back in "time axis' as you can 'do' in a graph by just 'moving' your pencil back along the abstract representation 'time graph axis'.

So practically no-one except you and paddo now still SERIOUSLY and REALLY 'believe in time travel' of any sort except in abstract concept/idea, not reality.

Motions can happen in all directions in space and REVERSE IN-SPACE direction. You can't REVERSE 'in-time direction' in any real sense whatsoever. Hence NO 'time travel' is or can 'happen' in reality. Ever. Period.

Hi PhysBang.

Actually, yes I do. A while ago I got the pleasure of reading through Maxwell's "Matter and Motion" and he lays out pretty much what I did there, explicitly noting that questions of space, time and movement were all linked together by a specific Set of related assumptions. He also notes that without these assumptions, one is unable to do physics. So he suggests that, until people can do better, we all accept that these assumptions are a part of physics.

Einstein actually did better: he replaced those assumptions with slightly different ones and he and others were able to show that we could do physics better (on a number of pragmatic grounds, including accuracy) with the new assumptions.

If someone wants to do away with time and replace it with motion, then they are free to do so if they can demonstrate that they can do the work of physics with those applications.

Thanks for the polite and courteous response on point, mate. Much appreciated.

Yes, as you just confirmed, they are all 'abstract assumptions', not reality-referential entities/mechanisms/processes etc. As Maxila has patiently and necessarily often pointed out, the ONLY real empirical observable and connection is the MOTIONS/CHANGES IN SPACE context, not an abstract 'spaceTIME' context which Albert himself was only an ABSTRACTION construct not the reality (we'll call it UNIFIED 'energy-space', as some mainstreamers are increasing doing because it represents real things not abstractions) which the 'spacetime' approach/method left behind because they hadn't enough empirical understanding of the underlying 'energy-space' at the time, as Einstein said...

More careful reflection teaches us, however, that the special theory of relativity does not compel us to deny ether. We may assume the existence of an ether; only we must give up ascribing a definite state of motion to it, i.e. we must by abstraction take from it the last mechanical characteristic which Lorentz had still left it. We shall see later that this point of view, the conceivability of which I shall at once endeavour to make more intelligible by a somewhat halting comparison, is justified by the results of the general theory of relativity.----Einstein

So it's time we went back to reality basics with the knowledge and insights and experimental techniques and computer simulations etc in order to review what we may have missed all this time because of the abstract-math approach which still doesn't treat/interpret the observbles in the reality context but the abstract context which effectively stifles any 'professional review' of the real entities etc from the get-go becaue of bias and pre-conclusions based on early abstraction/assumption which you mention above.

RC

More careful reflection teaches us, however, that the special theory of relativity does not compel us to deny ether. We may assume the existence of an ether; only we must give up ascribing a definite state of motion to it, i.e. we must by abstraction take from it the last mechanical characteristic which Lorentz had still left it(the ether). We shall see later that this point of view, the conceivability of which I shall at once endeavour to make more intelligible by a somewhat halting comparison, is justified by the results of the general theory of relativity.----Einstein

You quote the man, but obviously do not understand the English he is speaking. He wasn't talking about Relativity, he was discussing the possibility of the existence of ether in Relativity. Later on he explains that since the last possible characteristic an ether would have(movement)is eliminated by Relativity it is not logical to posit it's(the ether's) existence(IE there is no evidence that an ether exists, so why invent it).

Are you really that...er...intellectually challenged?

Grumpy

brucep said:
Nobody is changing the local measurement of the speed of light.
I didn't say they could. I said nobody can move away from their own frame (it doesn't make any sense either).

Hi Grumpy.

PhysBang

You cannot even describe a single event, much less a series of events that we call movement, without designating a point in time in the description.

Didn't you understand what Einstein explained about two simultaneous events being actually involved when you or I speak of 'time'? He said: "Like you observe the 'event' of the hand on your watch reaching 7 Oclock location on the dial, and the train pulling into the station."

See? YOU are the one in your 'observational construct' involving TWO EVENTS for your 'time' comparison to make sense, else there is nothing to 'compare to' and your 'time' concept is meaningless and only 'philosophical 'overlay' by YOU, not the observable reality events themselves IN COMPARISON motions/events construct.

When someone says they saw an explosion, for example, you can look all you like at that point in space but unless you did so at the exact moment when the explosion occurred you will not see that event. IE there can be no event without a time to occur within. There is no way to describe an event without including a specific time or series of times(as well as locations in space). The time is the stage upon which events occur, it is in no way inhibited by anyone's inability to measure it(which is all movement does, give you a means to measure it).

You are again effectively bringing purely 'philosophical concepts' and not real physical things to your 'overlay' ON observations, mate.

Consider: You are a fighter pilot at cruising at 30,000 feet, and you were already looking straight ahead through your HUD (ie, heads-up-display-on-screen) and a flak shell bursts within your field of HUD view WHICH ALSO displays the current TIME in your LOCAL 'time' coordinate. There are TWO events you see and COMPARE to tell what 'time' an event happened compared to the 'standard' timing event (your HUD clock display). You must be aware and compare BOTH events to make sense of it. Else it's just disjoint data until there is a construct for comparison of the two event occurrences to some 'standard' observational construct.

Again, as Albert made clear in his address quoted in earlier post, the 'spaceTIME' construct is and ABSTRACT thing, by design and intent to leave behind the last vestiges of real things. So 'time' CAN NOT BE a 'stage' or 'pre-requisite' or 'cause' or 'consideration' for ANYTHING happening before it DOES happen all on its own as part of the CONTINUAL universal processing which overall has NO 'beginning' or 'ending' point from which the UNIVERSE ITSELF has to 'start its clock/analysis' from.

The universe, unlike us humans, does NOT NEED to 'describe' OR 'analyze' anything; nor does it need' to 'tell time' before its real energy-space processes CONTINUE unabated whether we are here to 'observe', 'locate', 'time' and 'compare' events or not.

And if the universe didn't exist in itself physically really and mechanistically processing, then the idea/concept of 'time' would be a purely an academic and philosophical one, not 'real' or 'physically determining' of anything at all. That's the point Penrose and Einstein and Maxila and I and all others NOT in thrall to abstract 'spacetime' can see clearly NOW that we have escaped that 'abstractions thrall' by looking again at the reality left behind by the 'spacetime' approach long ago, as explained by Einstein himself in the previous quote.

RC
You quote the man, but obviously do not understand the English he is speaking. He wasn't talking about Relativity, he was discussing the possibility of the existence of ether in Relativity. Later on he explains that since the last possible characteristic an ether would have(movement)is eliminated by Relativity it is not logical to posit it's(the ether's) existence(IE there is no evidence that an ether exists, so why invent it).

Are you really that...er...intellectually challenged?

Grumpy

He was speaking of an approach which effectively IGNORES an real things and just abstracts/predicts based on observed motions/behavior. It stops considering the underlying real things (energy-space) and eventually substitutes the maths abstraction 'space-time' and goes from there....so effectively "by abstraction take from it the last mechanical characteristic" which the real things involve....in preference for the abstraction construct that followed. There is no 'space-time' in reality, only energy-space' (the motions in space being the observable processes of the features' of/on that energy-space for REAL.

Your reading bias is still set to 'belief confirmation', not 'objective take' in the whole context where Einstein himself went on later to bemoan...
Ever since the mathematicians invaded my theory, I don't understand it myself anymore!-----Einstein

Which is why your and poor pado's deluded 'belief' in 'time travel' in any real 'travel' in some 'abstract construct 'space-time' GRAPH CARTOON 'explanations' is not quite the basis for you and paddo to criticize Maxila or anyone else on the matter. Your 'beliefs' are no match for the reality in review lately.

So it's still "Warp Speed Mr Sulu!" for you and pado, is it? Mate, it's time to put away comic book 'understandings and beliefs' and other childish things, and step out into the reality which was left far behind by the mathematicians whom Albert jokingly but seriously prophetically warned were abstracting their way to incomprehensibility, even to the theory's originator way back then! Cheers.

Good morning, Grumpy.

Careful, mate. The 'spaceTIME' construct is an ABSTRACTION not the REAL THING in which things 'happen/move'. Here is Einstein again on the express approach/method OF 'abstraction' from reality and effectively leaving the mechanistic etc properties/entities/processes 'behind' in the math analysis/modeling approach they took back then...

No, it is real, very real, and it can be measured contrary to what you think....
And time travel ala the twin paradox can certainly happen if GR is valid, and that we all know it is.
You need to be careful also undefined in the silly unsupported claims you make as if they are a faitre complei, when they are just abstractions in your head.
Your delusions also continue in saying only me and Grumpy adhere to that opinion, when it is nearly all that have contributed save for you and Farsight.
So again, stop making stories up on the run.

Over to you for your usual scathing, ego intensive rant....
Happy sailing undefined.