Can Time Travel Truly Allow Us to Visit the Past?

[bayan]

do you people believe in time travel?

I do not mean to be able to slow the time down, but to actually go backwards in time!

Please give reason too (if possible

 

[Sirus]

Well, in theory you can travel into the future when you travel faster than light. But that is also impossible in theory, so it's a bit of a contradiction. For now, all this stuff is just theoretical.

 

[Gonzolo]

Well, in theory you can travel into the future when you travel faster than light. But that is also impossible in theory, so it's a bit of a contradiction. For now, all this stuff is just theoretical.

Isn't regular time dilatation "travel into the future"? Slightly less than the speed of light brings you there. Consider the twin "paradox". The one who has left the planet and come back is "in the future" just about as much as you would want him to be.

It is travel into the past which is more delicate. Nothing in conventionnal theories really allows it as far as I know.

 

[primal schemer]

Well, in theory you can travel into the future when you travel faster than light. But that is also impossible in theory, so it's a bit of a contradiction. For now, all this stuff is just theoretical.

You don`t need to go faster than the speed of light to go into the future.

I think there is a slight difference in terminology here. According to relativity it is possible for person A to travel into the future of person B. For example, if you remain on earth, and I get in a really fast spaceship and travel around at speeds close to the speed of light for a while, then it may take an hour or so of me flying around to travel a couple of years into your future.
(I don`t have the formulae for working out how fast/how long handy, but the speed would need to be very close to the speed of light.)
Getting back in time is a whole different story though...

Perhaps somebody could clear something up, but according to relativity, the closer you travel to the speed of light the faster (in time) you travel according to people standing still. So, if my reasoning is correct, if you are capable of traveling at a miniscule speed below the speed of light, then in theory you can travel as far in the future (according to other people) as you want.
So, (and I`m asking someone to clear this up rather than saying it is definitely true), would it be possible to travel, say, thousands of years into person B`s future in a fraction of a second if person A was going *really* close to the speed of light.

Anyway, the difference in terminology I mentioned at the start refers to the difference between MY future and YOUR future. It is possible to me to go into your future (and vice versa), but me going into my own future is an entirely different matter that brings up a whole load of other 'back to the future' style questions.

Although I have never heard of anything that will allow us to go back in time to, say, the stone age, I remember reading somewhere that it could be theoretically possible to set up some sort of portal at time X that will allow anybody to travel forwards and backwards between time X and X + Y. (where Y is a positive time). Although as far as I remember, this relied on *alot* of if's https://www.physicsforums.com/images/icons/icon9.gif
Unhappy

 

[Gonzolo]

So, (and I`m asking someone to clear this up rather than saying it is definitely true), would it be possible to travel, say, thousands of years into person B`s future in a fraction of a second if person A was going *really* close to the speed of light.

The answer "tends towards a yes", with serious limitations. What prevents us to apply this is the unimaginable energy that would be needed to accelerate someone to a sufficient speed. A Saturn rocket goes only a small fraction of c and most of its power is only to compensate the Earth's G-field. Now you need enough power to accelerate to near c, 4 times : away from the Earth + decceleration, and back. The faster you want to do this trip, and the further in the future you want to go, the more energy you need, and it is not a linear relation.

Then there is the fact that a human can only support a few g's comfortably. Time travel into the future in a fraction of a second would mean accelerating so fast... well I won't write what I imagine the person would look like.

 

[pervect]

do you people believe in time travel?

I do not mean to be able to slow the time down, but to actually go backwards in time!

Please give reason too (if possible

Time travel may be possible through wormholes. But do wormholes exist? It's hard to say at this point. Even if wormholes do exist, there are some mechanisms that may prevent them from becoming time machines (chronology protection postulates, due to Hawking).

There's a pretty good popular article on wormholes and time machines by John Cramer, a physicsist, reprinted from his "Alternate Views" column in analog.

http://www.npl.washington.edu/AV/altvw33.html

If you browse around this webstie, he's written a few other columns about the same topic, as more information became available.

 

[omin]

do you people believe in time travel?

I do not mean to be able to slow the time down, but to actually go backwards in time!

Please give reason too (if possible

I'm just beginning physics study, so take that in consideration when you read my answer.

Basic common sense says time travel is impossible. I think Newtons laws imply the impossibility also.

Reason: Each object that exists in all of the universe is dictated by the laws of physics. Time travel implies breaking the laws of physics.

Time travel into the future implies: I can slow the physics laws in my frame of reference, while the laws of physics operate at a faster rate outside my reference. But, that's not how physics works.

The clock inside a spaceship that leaves the Earth at near the speed of light will tick according to it's physical make-up, not it's relative speed to any thing else.

If a clock makes one tick every second, and it's going 1.0 meter per second, that means over one meter, one tick will sound. So, when it's going this velocity away from the Earth, one tick will have sounded and it will be one meter away from the Earth.

If it's going 1 million meters per second, one tick will occur every million meters. 3 million meters per second, will result in one tick every three million meters.

The clock will not slow down based upon speed. The rest of the universe will not speed up because of the clocks relative speed. Time is based upon the movement of objects in the universe, therefore time can't speed up or slow down either.

But, if other forces act upon things at high speed, causing what appears to be time travel, then it's a specific force that acts upon the clock, not mere speed.

Many claim, very fast speed causes time travel. Bull! Speed merely causes distance travel.

 

[Gerinski]

Reason: Each object that exists in all of the universe is dictated by the laws of physics. Time travel implies breaking the laws of physics.

Several interpretations of the laws of physics (as described by current theories) allow for time travel into the past theoretically, without creating any conflict with the laws themselves.
Wormholes, Frank Tipler's rotating cylinder, or cosmic strings are just some examples.

The problem is that the solutions allowing for time travel into the past require very extreme conditions, so we could not check them out so far (and we may never be able to do so). Time travel into the past is just possible theoretically (as a mathematical solution to the equations).

Even if the theoretical solution yields a time travel into the past, it's not clear at all which past it would be, the same that was experienced by the traveling entity (a time loop), or a different one (perhaps a parallel universe in the multiverse)

 

[mijoon]

...... I think Newtons laws imply the impossibility also....

This is the age of Einstein, not Newton. Even though Einstein himself was not happy about it, he had to admit that time travel is possible. Look up Godels solution, for example.

The effects predicted by relativity theory have been experimentally verified to many, many decimal places. And that's no bull.

 

[Gonzolo]

I'm just beginning physics study, so take that in consideration when you read my answer.

When you start learning about relativity, you will learn that Newton never asked himself whether the light coming from the headlamps of a moving car was traveling faster than that from a standing lamp-post. If you try to solve this problem, you come up with the conclusion that clocks can depend on nothing but speed. As any junior physicist and upwards, starting with Einstein, I can, with elementary mathematics, in less than a page of demonstration show that intervals of time between the ticks of a clock depends on its speed. Your reasoning is only o.k. if you're moving slowly, it doesn't work if you're going half the speed of light.

Elementary relativity says you can go into the future. (Particles do it all the time in accelerators.)

Advanced relativity wonders whether you can go into the past. (Only Doctor Who, Micheal J. Fox and the like have done this yet.)

 

[Ba]

And as I understand it that if you travel close to the speed of light then to the people in a different referance frame you will travel faster in time according to those people, but at the same time from your referance frame those people in the other referance frame will be traveling faster in time than you. So I think that if you go out and back close to the speed of light that your time phase to the people will be the same as their time phase to you. Maybe?

 

[Gonzolo]

And as I understand it that if you travel close to the speed of light then to the people in a different referance frame you will travel faster in time according to those people, but at the same time from your referance frame those people in the other referance frame will be traveling faster in time than you. So I think that if you go out and back close to the speed of light that your time phase to the people will be the same as their time phase to you. Maybe?

At some point, you have to turn around to meet each other again. If both reference frames turn around at exactly the same rate etc, you are right. If only one does and it comes back to join the other, the situation is asymetric and the "phase" as you call it is different, resulting in definitive time dilatation of the accelarated frame relative to the other.

 

[omin]

If an object must travel what we call forward through time, then relative to everything else, it must slow down while everything else speeds up.

The amount of energy it would expend, must then be drawn from it to the system outside itself.

Energy flows at a rate determined by the all things physical.

All energy is conserved, and all rates of flow of energy are consistent between objects that exist in the universe.

When the energy of the object that must slow down to travel through time flows backs to the system outside itself so it can move faster, there is a equal and opposite physical effect, which is the rate determined by physical laws, making it impossible for time to appear different to either reference frame.

I think the effects of time travel people are stating is just unawareness of some force acting upon the matter that appears to be traveling through time.

Fields of force of some sort seem like they could have an effect as things move at high speeds, where they don't have the same amount of an effect at low speeds. A frictive medium must create the rate of energy change, giving the illusion of time travel. With my limited knowledge, and I admit it is, time travel is only possible when things can't be accounted for. I say ignorance of some force makes time travel possible only.

 

[Gonzolo]

If an object must travel what we call forward through time, then relative to everything else, it must slow down while everything else speeds up.

Yes, its time must "slow down", not its speed. That happens with decaying particles.

The amount of energy it would expend, must then be drawn from it to the system outside itself.

Not necessarily.

Energy flows at a rate determined by the all things physical.

If you mean that it flows according to the laws of physics, I agree. But the fact that c is invariant is practically a law of physics now.

All energy is conserved, and all rates of flow of energy are consistent between objects that exist in the universe.

Rates of flow of energy... I agree that all must always be consistent.

When the energy of the object that must slow down to travel through time flows backs to the system outside itself so it can move faster, there is a equal and opposite physical effect, which is the rate determined by physical laws, making it impossible for time to appear different to either reference frame.

Not quite sure what you mean. When a rocket slows down near a planet, the planet couldn't care less. The equal and opposite effect is between the rocket and its fuel.

I think the effects of time travel people are stating is just unawareness of some force acting upon the matter that appears to be traveling through time.

What people? What force? There is no physical evidence of this "force" you mention.

Fields of force of some sort seem like they could have an effect as things move at high speeds, where they don't have the same amount of an effect at low speeds. A frictive medium must create the rate of energy change, giving the illusion of time travel. With my limited knowledge, and I admit it is, time travel is only possible when things can't be accounted for. I say ignorance of some force makes time travel possible only.

Well, until you can demonstrate that such a "force" and "frictive medium" exist, time dilatation is true, and has, on the other hand, been verified experimentally with very fast particles and very precise atomic clocks. "some sort of force", "seems", "think", and unstated "physical laws" won't do much to convince serious physicists. If you are confortable with classical mechanics (end of high school level), I invite you to grab any book on special relativity and look for a single mistake in the mathematical reasoning.

 

[bayan]

Well, until you can demonstrate that such a "force" and "frictive medium" exist, time dilatation is true, and has, on the other hand, been verified experimentally with very fast particles and very precise atomic clocks. "some sort of force", "seems", "think", and unstated "physical laws" won't do much to convince serious physicists. If you are confortable with classical mechanics (end of high school level), I invite you to grab any book on special relativity and look for a single mistake in the mathematical reasoning.

Those books are full of mistakes and i will someday prove it (Hopefully).

 

[Gonzolo]

Light momentum, increase of mass, a maximum speed that is constant, and time dilatation come from experimental observations themselves, not books.

What relativity books do is make sense of it all, binding these effects together in a coherent theory.

 

[omin]

Gonzolo,

A have a first clock tied to a string. At the other end of the string is the second clock. I swing the second clock around the first clock. I bring the second clock near the speed of light, while the first clock is at near rest compared to me.

The energy had to go through the first clock to get to the second clock.

With this in mind, did the second clock really move further than the first clock?

 

[Gonzolo]

The energy did not have to go through the first clock at all. You could simply put this 1st clock on a table nearby, unstringed and swing the second clock. When you stop swinging and compare the clocks, the one that has swinged (the second) will have lagged.

 

[omin]

The energy did not have to go through the first clock at all. You could simply put this 1st clock on a table nearby, unstringed and swing the second clock. When you stop swinging and compare the clocks, the one that has swinged (the second) will have lagged.

No, no. I'm implying a connection here that isn't as easy to see without a string. Let's add your third clock under the first clock.

But as far as the first two clocks, the energy must be via the first clock to get to the second clock, right? If not, how does the second clock move?

 

[Gonzolo]

Well I'm saying that string or not, connexion or not, there is a lag. The non-moving clock could be hanging from a blimp floating on Jupiter.

If you insist on having all the clocks on a string, let's stick with only two such that :

(pivot hand)-----(1stclock)-----(2ndclock)

then since the second clock has a greater speed, it lags relative to the first, it has more energy, more mass, and it is shorter.

Whether there is a first clock on the string or not is irrelevant to the 2nd. The second clock knows nothing of the first. No energy is transmitted via the first clock or anywhere. The first has its KE, and the second has its greater KE, and that's all.

The 2nd could have started moving by fixing a small rocket to it, but once it starts making revolutions, it doesn't stop (gravity might make it fall down), just like the Earth never stops spinning.

Now if you decide to pull on the string you can give it energy, but you don't have to do this anymore than a nail would. Any energy you would need is only to counter gravity and air friction.

 

[omin]

If you insist on having all the clocks on a string, let's stick with only two such that :

(pivot hand)-----(1stclock)-----(2ndclock)

then since the second clock has a greater speed, it lags relative to the first, it has more energy, more mass, and it is shorter.

I can't go that far yet. I need to stop you there.

The second clock has greater speed?

The pivot hand exerts a force upon the first clock.
The first clock exerts a force upon the string.
The string exerts a force upon the second clock.

The force is exerted upon the first clock is constant, but the first clock doesn't appear to be moving as fast as the second clock that is receiving about half of the force and expressing it as kinetic energy?

I'll claim the force in the first clock as more of a static (internal force) than kinematically expressed force, making the collective speed of each clock equal, thus energy equal?

Or is there energy loss outward from the second clock or inward flow to the pivot hand making a density of energy settle toward one of the clocks?

 

[NoTime]

do you people believe in time travel?

I do not mean to be able to slow the time down, but to actually go backwards in time!

Please give reason too (if possible

Sure.
Get on a fast enough plane and travel from say New York to California.
You can arrive before you left.
Even easier.
In some locations there is a local time warp. So you can simply walk across the street and end up a whole hour in the past.
Even easier still.
Live in the right location.
You don't have to travel at all. You jest end up in the past or future occasionally.

Did you mean travel to your past?
In that case - No.

 

[Gonzolo]

I can't go that far yet. I need to stop you there.

The second clock has greater speed? ?

Ok, first of all, I want to make it clear that whatever we learn in school (pre-university) is called classical physics (and electricity). For most people, it is all that they will ever need to know about physics, and even for most engineers (and I dare say most physicists), they will never have to use relativity (any extra years of study an engineer does is always for systems at low speeds : no relativity needed). What relativity does is account for the upper limit of speed, but it contains all of what school says, so it is crucial that you understand classical mechanics before going to far in relativity. The effects we are talking about here are only for fun (unless you ever become a theoretical physicist). But I think you're not through with classical physics. (It's ok though, we've all been there.)

Ok, back to the problem, now, but let's get the classical thing going first, so : masses instead if clocks, we don't need the needles.

Suppose you swing the masses at 1 revolution per second. Clearly, the 2nd one does a greater diameter : d2, than the 1st : d1. It therefore has a greater speed, d2/t > d1/t. This is totally classical, any engineer knows this. Same frequency of revolution, but different speed.

The pivot hand exerts a force upon the first clock.
The first clock exerts a force upon the string.
The string exerts a force upon the second clock.

Application of a force doesn't mean using energy : remember W = fd. If d is 0, W is zero, and f and d must be in the same direction. Our swinging masses have d and f in perpendicular directions => no energy is used (f along string, d on circle diameter).

The force is exerted upon the first clock is constant, but the first clock doesn't appear to be moving as fast as the second clock that is receiving about half of the force and expressing it as kinetic energy?

The force is split in two. There is no "appear", the speeds are completely (classically) different as I said above.

I'll claim the force in the first clock as more of a static (internal force) than kinematically expressed force, making the collective speed of each clock equal, thus energy equal?

No, they are exactly the same types of force, both centripetal and static. There is no "collective speed", see what I said above. Only a unique angular speed. But all I have said about relativity applies to linear speed (length per second), not angular (angle per second). I'm always talking about linear speed (that is what c is.).

Or is there energy loss outward from the second clock or inward flow to the pivot hand making a density of energy settle toward one of the clocks?

No energy loss at all. No flow of energy. Only balanced forces. Let's get this classical thing right before going back to relativity.

 

[ArmoSkater87]

Sure.
Get on a fast enough plane and travel from say New York to California.
You can arrive before you left.
Even easier.
In some locations there is a local time warp. So you can simply walk across the street and end up a whole hour in the past.
Even easier still.
Live in the right location.
You don't have to travel at all. You jest end up in the past or future occasionally.

Did you mean travel to your past?
In that case - No.

By saying "fast enough" I am guessing you mean faster than the speed of light, which we all know is impossible. So from your example it would be impossible to time travel into the past, but it would be possible to time travel into the future because of time dilation.

As for time travel to the past, there are ways to theoretically do it. One way is to use a cosmic string (i think that's what its called). A cosmic string is i believe left over from the big bang and has a very high density, and causes the space around it to warp dramatically. You can think of the warp as a pizza made into a cone by cutting one slice out. Since light goes straight, light would have to travel down and up the inside of the cone, taking a longer time, while you can take a short cut around the cone. This makes it seem like you traveled faster than lightspeed because you got to the other side before the light would. Since you went faster than light did, you traveled into the past.

Another way is by using a black hole. If black holes spin, then that means because of its enormous gravitational field, it bends the space around it so much that it spins it around while the black holes is spinning it self (sorry for the bad terminology, i don't know how to really explain it). Now predend like you went next to the black hole with a spaceship and started traveling around the black hole with the spaceship at very high speed, close to the speed of light. So someone outside the spinning space and huge warp, it would seem like the spaceship is traveling faster than light because the space itself it moving with the spaceship also, giving the impression that the ship is going faster than light to someone outside the space where the gravity has that kind of an effect.
There are time machines that are being built right now that are similar to the black hole situation, one of them will have a cilinder where there would be very high energy laser beams circling around, which bend the space a great deal and in a sense, also bend time into a "loop" if u think of time as a straight line.

Anyways, to put it short, i don't know all that much about time travel, i just watch a lot of TV programs, but i do know that the laws of physics don't forbid the possibility of time travel to the past, there are ways of geting around other laws that do forbit it, like traveling faster than the speed of light.

 

[Gonzolo]

By saying "fast enough" I am guessing you mean faster than the speed of light, which we all know is impossible. So from your example it would be impossible to time travel into the past, but it would be possible to time travel into the future because of time dilation.

No, it is called a joke, related to time zones.

 

[ArmoSkater87]

?

 

[Gonzolo]

NoTime is referring to the fact that if you leave New York by jet at 7 am (sunrise), you will arrive in L.A. at about 10 am New York Time (it takes about 3-4 hours to go from New York to L.A.).

But during this time, the Earth has rotated so that it is now sunrise in L.A., so perhaps 7 am local time.

Time zones... jet lag... GMT... Eastern time... Central time... "Tonight at 8/7 central..."

Hopefully, no one confuses this with relativity.

 

[PatPwnt]

Yes, its time must "slow down", not its speed. That happens with decaying particles.



Not necessarily.


If you mean that it flows according to the laws of physics, I agree. But the fact that c is invariant is practically a law of physics now.



Rates of flow of energy... I agree that all must always be consistent.



Not quite sure what you mean. When a rocket slows down near a planet, the planet couldn't care less. The equal and opposite effect is between the rocket and its fuel.



Well, until you can demonstrate that such a "force" and "frictive medium" exist, time dilatation is true, and has, on the other hand, been verified experimentally with very fast particles and very precise atomic clocks. "some sort of force", "seems", "think", and unstated "physical laws" won't do much to convince serious physicists. If you are confortable with classical mechanics (end of high school level), I invite you to grab any book on special relativity and look for a single mistake in the mathematical reasoning.

Haven't they also tested it with super sonic jets?

 

[ArmoSkater87]

NoTime is referring to the fact that if you leave New York by jet at 7 am (sunrise), you will arrive in L.A. at about 10 am New York Time (it takes about 3-4 hours to go from New York to L.A.).

But during this time, the Earth has rotated so that it is now sunrise in L.A., so perhaps 7 am local time.

Time zones... jet lag... GMT... Eastern time... Central time... "Tonight at 8/7 central..."

Hopefully, no one confuses this with relativity.

Ohhhhh...LOL, wow i was being dumb, i get what he meant now.

 

[NoTime]

Ohhhhh...LOL, wow i was being dumb, i get what he meant now.

Wow

I've had people really misread my comments before, but...

Glad you finally got it.

 

[pervect]

Ok, first of all, I want to make it clear that whatever we learn in school (pre-university) is called classical physics (and electricity). For most people, it is all that they will ever need to know about physics, and even for most engineers (and I dare say most physicists), they will never have to use relativity

IMO this is becoming less and less true as technology progresses.

Precision timekeeping applications now have to routinely account for general relativistic effects, so anyone involved in that field will need some familiarity with not only special, but general, relativity. GPS systems also involve relativity (of both sorts). For physicists, anyone who works with a particle accelerator will use relativity.

 

[Gonzolo]

Haven't they also tested it with super sonic jets?

I believe so, with extremely precise atomic clocks.

And pervect's post above suggests that it might have to be accounted for in GPS systems.

 

[pervect]

Here's a URL and a quote as far as relativity and GPS goes

http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Unit5/gps.html

Because an observer on the ground sees the satellites in motion relative to them, Special Relativity predicts that we should see their clocks ticking more slowly (see Lecture 32). A straightforward calculation using special relativity predicts that the on-board atomic clocks on the satellites should fall behind clocks on the ground by about 7 microseconds per day because of the slower ticking rate.

Further, the satellites are in high orbits, where the curvature of spacetime due to the Earth's mass is less than it is at the Earth's surface. A prediction of General Relativity is that clocks closer to a massive object will seem to tick more slowly than those located further away (see Lecture 20 on Black Holes). As such, when viewed from the ground, the clocks on the satellites would appear to tick faster than identical clocks on the ground. A calculation using general relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day.

The combination of these special and general relativitic effects means that, if not accounted for, the clocks on-board each satellite would tick faster than clocks on the ground by about 38 microseconds per day (45-7=38)! This sounds small, but the high-precision required of the GPS system requires nanosecond accuracy, and there are 1000 nanoseconds in a microsecond. If these effects were not taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and in general errors in global positions would accumulate at a rate of about 10 kilometers each day!

 

[Gonzolo]

Indeed. A further motivation for me to dive into those tensors.

 

[omin]

Suppose you swing the masses at 1 revolution per second. Clearly, the 2nd one does a greater diameter : d2, than the 1st : d1. It therefore has a greater speed, d2/t > d1/t. This is totally classical, any engineer knows this. Same frequency of revolution, but different speed.

Application of a force doesn't mean using energy : remember W = fd. If d is 0, W is zero, and f and d must be in the same direction. Our swinging masses have d and f in perpendicular directions => no energy is used (f along string, d on circle diameter).

Application of Force means energy is expressed. Distance is a consequence of the mass's Acceleration. Acceleration of this mass is a consequence of a Force exerted upon it, which requires another mass with velocity and a collision of both masses. If Distance is zero, no Force exists which means no Energy is expressed. And, if no Energy is expressed, no Force can exist.

Force is expressed when change of velocity occurs. Although the distance between the first and second clock appears to not change because of the string, they are accelerating in relation to the human who spins them. This force is applied directly to the first clock and must be maintained to keep the clocks spinning. A constant force is exerted upon the clocks and therefore is an expression of energy.

The force is split in two. There is no "appear", the speeds are completely (classically) different as I said above.

The speed (motion) is implied to be internal in the first clock, because the force upon the first clock must supply constant supply force for the second clock.

No, they are exactly the same types of force, both centripetal and static. There is no "collective speed", see what I said above.

When I think of static force, it means the movement is not as apparent to my vision and I have to use deduction to find it, where kinetic force means I notice it visually and is axiomatic. I don't see the first clock moving as much as I see the first clock. I know the first clock isn't loosing it mass where force occurs, so it looses motion outwardly to the second clock. This motion travels to the string and then to the second clock. It is a wave of energy.

What I don't know is if the wave of energy is building up toward the outside or if it's perfectly distributed.

Only a unique angular speed. But all I have said about relativity applies to linear speed (length per second), not angular (angle per second). I'm always talking about linear speed (that is what c is.).

When a constant supply of energy is supplied to this circumstance, and we isolated all outside forces upon this system (for now), we may see this in a linear way, because all things will settle as constant. So we may apply the what you are calling linear logic to it.

No energy loss at all. No flow of energy. Only balanced forces. Let's get this classical thing right before going back to relativity.

But how is the balance of forces occurring here expressed? Perfect distribution of force across the first clock and across the second clock or is there a greater density of force, thus energy being expressed in one the clocks?

Once we get through this part, we can deal with the time travel question.

 

[Gonzolo]

...constant force is exerted upon the clocks and therefore is an expression of energy.

This not how energy is defined in standard physics. When a rock is set on the ground, gravity exerts a force on the rock, the rock exerts a force on the earth, yet no energy is converted, because W = fd = f(0) = 0. For energy to be used, the rock has to move in the direction of the force. If you open a trap door under the rock, then there is energy conversion, because d will not be zero, the rock will move along the force (it will gain kinetic energy).

Imagine a spinning dumbell in space. Where is energy used? There are millions of forces between its atoms, yet it doesn't use energy at all. I don't see what you mean by "expression of energy". Any energy that is used to keep the clock in the air is to compensate for losses due to gravity (up and down oscillations, which we should ignore) and a bit for friction. In space, no energy would be needed to keep it going.

The speed (motion) is implied to be internal in the first clock, because the force upon the first clock must supply constant supply force for the second clock.

I don't see what you mean by "internal speed".

When I think of static force, it means the movement is not as apparent to my vision and I have to use deduction to find it, where kinetic force means I notice it visually and is axiomatic. I don't see the first clock moving as much as I see the first clock. I know the first clock isn't loosing it mass where force occurs, so it looses velocity outwardly to the second clock. This velocity travels to the string and then to the second clock. It is a wave of energy. I know this much.

Static forces means the forces are in equilibrium. Whereas Dynamic forces means their is movement along forces. You might call our system kinematic I suppose (not dynamic though), but in static and kinematic cases, there is no tranfer of energy. When something is already spinning (kinematic), centripetal force balances centrifugal force, but no force is along the motion.

What I don't know is if the wave of energy is building up toward the outside or if it's perfectly distributed.

There is no build up of energy, most was given in the beginning, whatever you add is to compensate for losses due to gravity (this should be ignored). There is more towards the outside though. A simpler system (without losses) is a spinning dumbell in space. You do not have to constanly supply energy to compensate losses in this case.

(mass)----(clock 1 = pivot)----(clock 2)

When a constant supply of energy is supplied to this circumstance, and we isolated all outside forces upon this system (for now), we may see this in a linear way, because all things will settle as constant. So we may apply the what you are calling linear logic to it.

If you do wish to supply constant energy (over what is need to compensate up and down oscillations), then it will be spinning faster and faster and faster and faster and this complicates things besides the point.

 

[omin]

This not how energy is defined in standard physics. When a rock is set on the ground, gravity exerts a force on the rock, the rock exerts a force on the earth, yet no energy is converted, because W = fd = f(0) = 0.

This is a contradiction in terms. We must not confuse things. The basis of the argument without this defined will make nothing intelligeable. I can't go through everything and do a logic operation without making it too time consuming. I'm not moving on until we speak clearly on this issue.

Force implies motion. Where there is no motion there is no force. Where there is gravity, there surly is motion, even internally.

 

[Gonzolo]

No problem. You must first understand that a force, as defined in physics, (and as can be extended in all fields of life), does not necessarily imply motion, and where there is no motion, there can be forces (in equal and opposite directions, such as the net force is zero). The walls of a house exert a force on the roof all the time. Yet nothing moves.

 

[omin]

No problem. You must first understand that a force, as defined in physics, (and as can be extended in all fields of life), does not necessarily imply motion, and where there is no motion, there can be forces (in equal and opposite directions, such as the net force is zero). The walls of a house exert a force on the roof all the time. Yet nothing moves.

Force always implies motion. Otherwise, potential energy would be matter of some sort that created velocity, rather than having it internalized in some way. Energy is niether created nor destroyed.

What cannot be confused here, so we can move on, is the differentiation between the momentum concept and the energy concept. Momentum is based upon vector principles and energy is based on scalar principles. The concept of momentum seems conventionally to not represent motion that is internalized or expressed in small particle high velocity forms not seen by the human eye. Energy does account for this internalized motion or unseen particle accelerations.

Energy can be traced in all forms directly sensed or deduced because the energy concept covers all known forms when motion tranfers during interaction. Momentum may not be fully accouted for because it's limited to one form, for example the visually sensed motion form implied by it's vector limitations.

Does this help with distinguishing the contradiction of say that gravity force upon the rock, the trapdoor underneath the rock is the support force, but their the net force is zero. Force is zero if we use momentum, but not energy.

Let's stick to the concept that covers all bases.

If so, let's finish the rotational motion clock example, because I want to point out the example serves as a basis to prove time travel is not possible.

 

[Gonzolo]

"Force always implies motion."

Where did you learn that?

 

[spacetime]

beleive

You say beleive? yes I beleive. But I don't know the reason. But I have faith. And I feel physics, to some extent, progresses by having faith in certain things. It may not be able to prove them.

spacetime
http://www.geocities.com/physics_all/index.html

 

[Ba]

The normal force does not imply motion neither does the frictional forces, they are counteracting forces.

 

[omin]

"Force always implies motion."

Where did you learn that?

It's been an ongoing assumption of mine for awhile. Here is the basis of my reasoning:

Since, acceleration is based upon velocity, acceleration cannot exist without velocity. Velocity is based upon speed and direction. Velocity cannot exist without speed. Speed is based upon the displacement. Speed cannot exist without displacement. Displacement is based upon measurement and motion. Displacement cannot exist without motion.

Since, force is based upon acceleration, acceleration upon velocity, velocity upon speed, speed upon displacement, and displacement upon motion, force cannot exist without motion.

 

[Gonzolo]

I see. However, be wary of personnal theories here, the Theory Development section more appropriate for that. The rest of the site uses ands stick to standard physics.

Note that each of : acceleration, velocity, and position can be zero independantly. A force is a vector which can assume any value, independantly of what it acts upon, and it is quite stricly defined mathematically. What you are introducing is basically acceleration under a new name.

It is the net force which is F = ma. If this is zero, then a is zero, but not necessarily v and x. We may well have F = F1 + F2 + F3 +... where each of F1, F2 ... can be defined as what ma would be in the absence of the other forces.. It is quite possible that F1, F2, and F3 sum together to make 0 = ma, in which case we would a mass with a = 0. Once this result is obtained, we could care less about F1, F2, F3 ... individually, but it is them that got us to a, v and x ultimately. They are quite useful in this respect. I have yet to see how you would solve such a problem with your assumption.

The spinning clocks are still interesting, see you in the other thread.

 

[omin]

When I learned to count it began with the number one, not zero. Zero has never been taught to me as a value.

This assuption I'm introducing a new theory is smattering. That's what the physics books are implying and teaching, I've checked through the classic mechnanics of atleast four, and nothing is contradictory about what I've said about Net Force equaling zero and energy concepts.

This is the proof I have to offer: Force that equals zero only means that it is not sensed and implies momentum concepts, vs. energy which accounts for the motion that seems to disappear or cancel.

Do you have proof that proves what I am saying is incorrect in representing things accurately?

And just because a book may not explain a nuance of classic physics doesn't mean it doesn't exist like: velocity is just average velocity, which means velocity never truly occurs in perfection, but acceleration does.

 

[Ba]

What about weight and normal force, these two forces and these cancel out to 0 with respect to an outside observer. And yet people still measure weight and compare it to other people's weight. Also the normal on a horizontal surface is used for friction it's there and it's needed with the coefficiant of friction to find the frictional force. Yet all together the vertical force is zero that's not to say these two forces aren't acting on it. After all it's a totally different zero force than somebody in freefall.

 

[Gonzolo]

When I learned to count it began with the number one, not zero. Zero has never been taught to me as a value.

This assuption I'm introducing a new theory is smattering. That's what the physics books are implying and teaching, I've checked through the classic mechnanics of atleast four, and nothing is contradictory about what I've said about Net Force equaling zero and energy concepts.

This is the proof I have to offer: Force that equals zero only means that it is not sensed and implies momentum concepts, vs. energy which accounts for the motion that seems to disappear or cancel.

Do you have proof that proves what I am saying is incorrect in representing things accurately?

And just because a book may not explain a nuance of classic physics doesn't mean it doesn't exist like: velocity is just average velocity, which means velocity never truly occurs in perfection, but acceleration does.

If it suits your needs, I have no problem with that. But until I learn alternative expressions for rotary motion (which I am 100% open to), I see no reason for abandoning centripetal and centrifulgal forces. The concepts have proven themselves useful beyond Newton's wildest dreams. Another example is that we couln't find the radius of the trajectory of an electron in a B-field in a simpler way.

 

[omin]

Ba,

Istn't the vertical force implied in the coefficiant of friction?

 

[Alkatran]

Otherwise, potential energy would be matter of some sort

I found that quote funny.

Anyways, energy is NOT force.

People often get confused about this concept because of electricity. They 'use' electricty. Real energy never gets 'used'. The kinetic energy in something can move it forever!

A good example is this: if energy is exchanged or expended because of forces, what happens to a rope strung between two walls? (taught) We'll say this rope won't ever break. Since there is a force being exerted on the rope it must eventually 'run out' of energy right? Then what, it can't pull at all? You could start pulling at that rope and stretch it forever!

Also, acceleration does not imply speed, it implies CHANGE in speed. Energy does not imply force and force does not imply energy. Think of it this way: I accelerated at 5 kajillion meters per second per second for 0 seconds.

How much did my speed change? Well duh, 0. There was no time for it to happen! It's THE SAME THING for force and energy. There was no distance for the energy to change over!

Don't believe me? Look at the units. Speed is acceleration * time. Energy is force * distance. For change in speed from acceleration you need time. For change in energy from force YOU NEED DISTANCE.

 

[Ba]

Istn't the vertical force implied in the coefficiant of friction?

No the coefficient of friction is the roughness of the surface, the force of friction is the coefficient times the normal force (vertical force).