Why two mass attracts each other?

[hansda]

if it is then i have answered your question way before.. Did you read that comment?

What is your logic?

 

[hansda]

No. Proper time is not dependent on clocks at all.

See wiki on proper time.

See the following wiki quote on proper time:

In relativity, proper time is the elapsed time between two events as measured by a clock that passes through both events. The proper time depends not only on the events but also on the motion of the clock between the events. An accelerated clock will measure a smaller elapsed time between two events than that measured by a non-accelerated (inertial) clock between the same two events. The twin paradox is an example of this effect.

From this wiki quote, it can be said that "proper time" is dependent on clock.

 

[ash64449]

What is your logic?

Equivalence principle.

It says that acceleration is indistinguishable from gravitational effects.

And you know that gravity is always attractive.

So you can change the above statement and say:

Acceleration is indistinguishable from a force that acts like attractive.

And note that this cannot work for electrostatic effects. By this i mean the effect of positive charge attracting a negative charge because Charge is considered a fundamental Quantity and that fundamental quantity is the one that causes attraction.

And Mass is a fundamental quantity. It was earlier thought that this fundamental quantity is the one that causes gravitational attraction.

But we know that it works quite differently because of relativity.

 

[ash64449]

See wiki on proper time.

See the following wiki quote on proper time:

From this wiki quote, it can be said that "proper time" is dependent on clock.

Yes.. but proper time can indeed on special circumstances be measured by the clocks.

Note what actually Wikipedia says. it depends on motion or direction taken by the clocks and as a result they measure different proper time.

 

[ash64449]

You should first understand what proper time actually means..

Proper Time is the invariant interval between the two events. and sometimes it can be measured by the clocks.

I will tell you the reason why proper time is invariant for SR and why it is not for GR. And because it is not applicable for GR, and that is why i said that your arrow of time is not same as proper time.

Think about a smooth fabric of space-time.. That part of the space-time is flat. So that region of space-time is called inertial reference frame.

Think about the two events. In the space-time,these two events is invariant.. It can never change.

Because different bodies move in different state of uniform motion,they will disagree on the "timing" of events and spatial separation.
But they will agree with the invariant interval between the two events.

If the invariant interval is time-like, that invariant interval is called proper time and that is the reason why i said proper time is invariant.

Now think about those two events itself but now the space is curved.now note how the invariant interval between the two events curves.

So as a result,they will have different proper time for the object that causes the curvature.

But if we look at another object that has different mass(energy),it will have different curvature for the same events and as a result they will say they have different proper time.

I hope you have understood.

To other poster.. I am open for correction.. There might be mistakes and i am happy if you point it.. because as a result i will learn new thing.

EDIT: Note that uniform motion cannot cause any curvature in space-time and that is the reason why everyone agrees on proper time.

I think this is exactly what Wikipedia said...

 

[hansda]

Equivalence principle.

Which equivalence principle, you are following? There are many equivalence principles. Give the specific statements of the principle you are following or give reference.

It says that acceleration is indistinguishable from gravitational effects.

Give reference.

And you know that gravity is always attractive.

That is Newtonian concept. Einstein's concept is different.

So you can change the above statement and say:

Acceleration is indistinguishable from a force that acts like attractive.

You are following 'Newtonian model' or 'Einstein's model' or mixing both the models?

And note that this cannot work for electrostatic effects. By this i mean the effect of positive charge attracting a negative charge because Charge is considered a fundamental Quantity and that fundamental quantity is the one that causes attraction.

OK.

And Mass is a fundamental quantity.

NO. Energy is more fundamental than mass.

It was earlier thought that this fundamental quantity is the one that causes gravitational attraction.

Are you referring Newtonian model?

But we know that it works quite differently because of relativity.

I think here you are considering 'Einstein's model'.


I think perhaps you are mixing up the 'two models of gravity'. Consider any one model and try to explain.

 

[hansda]

You should first understand what proper time actually means..

Proper Time is the invariant interval between the two events. and sometimes it can be measured by the clocks.

I will tell you the reason why proper time is invariant for SR and why it is not for GR. And because it is not applicable for GR, and that is why i said that your arrow of time is not same as proper time.

Think about a smooth fabric of space-time.. That part of the space-time is flat. So that region of space-time is called inertial reference frame.

Think about the two events. In the space-time,these two events is invariant.. It can never change.

Because different bodies move in different state of uniform motion,they will disagree on the "timing" of events and spatial separation.
But they will agree with the invariant interval between the two events.

If the invariant interval is time-like, that invariant interval is called proper time and that is the reason why i said proper time is invariant.

Now think about those two events itself but now the space is curved.now note how the invariant interval between the two events curves.

So as a result,they will have different proper time for the object that causes the curvature.

But if we look at another object that has different mass(energy),it will have different curvature for the same events and as a result they will say they have different proper time.

I hope you have understood.

To other poster.. I am open for correction.. There might be mistakes and i am happy if you point it.. because as a result i will learn new thing.

EDIT: Note that uniform motion cannot cause any curvature in space-time and that is the reason why everyone agrees on proper time.

I think this is exactly what Wikipedia said...

What do you mean by the word "invariant"?

 

[Tach]

When we meet up at event2 a year later, your clock reading is lower than mine, and you have experienced 11 months of time.

Correct.

But the separation between event1 and event2 is the same for both of us.

You just contradicted what you said above, so this is false.

We don't miss each other by a month.

Correct application of SR says that you are wrong. Markus told you this twice already.

 

[Farsight]

...So she experiences acceleration at three points during her journey, which is exactly what induces the differences in proper times between the observers.

That's incorrect. We can set up two twins scenarios. In scenario¹ twin B¹ goes on a one-light-year round trip. In scenario² twin B² goes on a two-light-year round trip. They both experience identical accelerations. However the proper-time difference between A¹ and B¹ is not the same as the proper-time difference between A² and B². Acceleration is needed in each scenario, both of which consist of the initial departure event and the final homecoming event. It's also needed to achieve relative motion. But it's that relative motion along with distance which induces the difference in proper times.

Note that this is all about proper times, not coordinate times.

I didn't say it was about coordinate times. The proper times are merely the number of reflections in their respective parallel-mirror light clocks. They cannot compare the number of reflections unless they have an initial and final event where they're both at the same location. They synchronise their clocks at the initial event and compare readings at the final event.

You simply do not get any paradoxes when working only in purely inertial frames - I can even prove this to you mathematically, for the general case. Would you like to see it?

No, because there simply aren't any paradoxes anyway. But speaking of purely inertial frames, one passing-clock scenario involves triplets. Triplet B passes triplet A and shouts out "What time is it?" Triplet A tells him, and B sets his clock accordingly. He then passes triplet C coming the other way, who shouts out "What time is it?" Triplet B tells him, and C sets his clock accordingly. Triplet C later crashes into triplet A, and their clocks are damaged and so stop. The difference in their readings is as per the standard twins scenario, but depends on relative motion and distance rather than acceleration per se. Like I said you need the acceleration to get relative motion, and of course the BC handover emulates the travelling-twin turnaround which is a deceleration then an acceleration. But note that here we have three inertial frames A B and C. The accelerations in the standard twins scenario can be idealised as instantaneous changes-of-frame A to B to C then back to A. Also note that every time one triplet passes another, they each claim that the other's clock is running slower than his own. But there's no paradox to it, it's just relativity. Again, see the Simple inference of time dilation due to relative velocity. It's due to relative velocity (I said relative motion), not acceleration per se.

 

[Farsight]

Another funny mistake, John, that illuminates your level of understanding, or lack of thereof. The twins paradox is all about elapsed proper time, not about clock rate.

The clock rates aren't the same. If they were, the travelling twin wouldn't come back time-dilated, would he now? And note that proper time is merely the number of reflections in the parallel-mirror light clock. That's all it is. There's no time flowing between the mirrors. They aren't literally "measuring the flow of time".

You are freely mixing up two different concepts. Markus nailed you further on your lack of understanding of elapsed proper time as a function of path through spacetime.

I'm not mixing them up at all, and Markus didn't nail me. I explained the twins paradox using light paths lengths through space, referring to the simple inference of time dilation due to relative velocity which is in turn based on Pythagoras's theorem. Elapsed proper time isn't actually "a function of path through spacetime". Spacetime is an abstract mathematical space, typically depicted as a "block universe". It presents all times at once, and therefore is static. The travelling twin moves through space, not along some path through spacetime. There is no motion in spacetime, or through it. So elapsed proper time is a function of path through space, which is modelled using spacetime.

but the separation between event1 and event2 is the same for both of us.

You just contradicted what you said above, so this is false.

No I didn't, and it's true. The separation is given by the light-path-length. Check it through.

We don't miss each other by a month.

Correct application of SR says that you are wrong. Markus told you this twice already.

Tach, you don't end up living in my past! Look, if you'd like me to explain this to you some more, just say the word. Alternatively if you prefer to be insincere, that's up to you.

 

[Undefined]

Relativity is not Newtonian mechanics.

Personal attacks, no. All I'm saying is that Farsight may suffer from Shell Shock and that could be the reason I don't understand him. I still try to see the good in everyone. But yes, maybe this is my failing.

Who said it was? The point was that according to SR, it is only relative motion speed only, not acceleration, which determines "time dilation" effects observed by one observer of the other's motion/speed. This is what the "experts" have been telling the "cranks" for years now in their "corrections" of the "crank" impression that accelerations were important in time dilation effects/differences between clocks in relative motion. Now Tach and others claim that accelerations are relevant after all? Does it strike you as funny that the "cranks" were right all along, and now Tach invokes acceleration history as part of the "explanation" which he and the other "experts" previously rejected when it was invoked by "cranks"?

And if Farsight kept saying the same "personal baiting" things to you that you keep posting about him, would he be reported for "breaking site rules" and get a warning and suspension? Or would he be allowed to get away with it like you seem to be? About your claim: "I still try to see the good in everyone." Can you support that claim with reference to consistent number of posts of yours where this is sincerely evident and not sarcastically meant?

 

[Undefined]

Another funny mistake, John, that illuminates your level of understanding, or lack of thereof. The twins paradox is all about elapsed proper time, not about clock rate. You are freely mixing up two different concepts.
Markus nailed you further on your lack of understanding of elapsed proper time as a function of path through spacetime.

Why do you post this to Farsight as if it explains or supports anything except your and Markus Hanke's about face concerning the role of acceleration history in SR scenarios? For years I have read you and other "experts" tell "cranks" that (non-gravitational) acceleration history has no effect on time dilation observed between purely relative motion/speed frames. Now when it is convenient for your "corrections", (non-grav) acceleration history is all-important all of sudden? Does this mean that the "cranks" have been correct all along, and you have been wrong all along?

 

[Beer w/Straw]

Blah blah blah.

You'd argue anything for Farsight. As if it would magically give credence to your own delusional pseudoscience. Hopefully this will give you pause for introspection. Still, I'm betting that you wont shut up under your own powers.

Oh, and your arguments have always been inconsistent fantasies just incase you need a bit more encouragement. I can't say I envy you for your neurosis. Get well soon.

 

[Tach]

duplicate

 

[Tach]

When we meet up at event2 a year later, your clock reading is lower than mine, and you have experienced 11 months of time.

In mathematical terms, the "stay at home" twin measures

$$T=1yr$$ on his clock

while the "traveling twin" measures

$$\tau=\int_0^T{\sqrt{1-(v/c)^2}dt}<T$$

But the separation between event1 and event2 is the same for both of us. We don't miss each other by a month.

Wrong: $$\tau=\int_0^T{\sqrt{1-(v/c)^2}dt}<T$$

$$\tau=11mo$$ and $$T=1yr$$

This is freshman physics , John, when will you ever learn?

 

[Undefined]

You'd argue anything for Farsight. As if it would magically give credence to your own delusional pseudoscience. Hopefully this will give you pause for introspection. Still, I'm betting that you wont shut up under your own powers.

Oh, and your arguments have always been inconsistent fantasies just incase you need a bit more encouragement. I can't say I envy you for your neurosis. Get well soon.

How can you get that from my post? I was neither arguing for or against anything Farsight said or didn't say, I was posting about what Tach and Markus Hanke said about acceleration as part of their "explanation" and "correction" of what Farsight said or didn't say. There is a difference, yes? I addressed Tach's and Markus Hanke's posts as to their consistency with what "experts" have been telling the "cranks" for years about acceleration NOT being an effective factor in SR time dilation observed effects on clocks etc. Have you got that straight please before making more unsubstantiated claims about what I was addressing, Beer w/Straw? So you keep baiting and flaming and pretend to the high ground in some way based on your mistakes? Is that a new way of "doing science" which you recommend to newbies here?

 

[Markus Hanke]

It's due to relative velocity (I said relative motion), not acceleration per se.

Wrong. And not only is it wrong, but it also directly contradicts directly the source you yourself referenced !
So once again - what is called the "twin paradox" in physics literature is not just any old gedanken experiment, but a very specific set of circumstances, namely the comparison between an inertial and a non-inertial frome of reference in terms of the proper times they measure. That is how "twin paradox" is defined :

http://dictionary.reference.com/browse/twin+paradox

You can come up with any differing setup you like, that's up to you, but then it will no longer be the "twin paradox", and you shouldn't call it that.

In the classical "twin paradox" as defined above, the difference in proper times is due to acceleration, not relative motion, just as the definition says. Mathematically, the stay at home twin measures a proper time between events A and B of

$$\displaystyle{\tau _{stationary}=\int_{A}^{B}\sqrt{\eta _{\mu \nu }dx^{\mu }dx^{\nu }}}$$

whereas the travelling ( and accelerating ) twin measures

$$\displaystyle{\tau _{travelling}=\int_{A}^{B}\sqrt{g _{\mu \nu }dx^{\mu }dx^{\nu }}}$$

which are quite obviously not the same, even though they connect the same two events A and B in space-time. If both frames were somehow inertial ( which, of course, is impossible given the setup ), they would both measure

$$\displaystyle{\tau =\int_{A}^{B}\sqrt{\eta _{\mu \nu }dx^{\mu }dx^{\nu }}}$$

meaning their proper times always agree. In fact, the only way to get a disagreement in proper times when connecting the same two events in space-time is for the metric tensors of the reference frames to be different, as in the above; and any metric tensor differing from $$\eta _{\mu \nu }$$ means that the observer experiences acceleration.

 

[Markus Hanke]

Why do you post this to Farsight as if it explains or supports anything except your and Markus Hanke's about face concerning the role of acceleration history in SR scenarios? For years I have read you and other "experts" tell "cranks" that (non-gravitational) acceleration history has no effect on time dilation observed between purely relative motion/speed frames. Now when it is convenient for your "corrections", (non-grav) acceleration history is all-important all of sudden? Does this mean that the "cranks" have been correct all along, and you have been wrong all along?

See my last post. What is called the "twin paradox" is a very specific scenario that involves the comparison between two frames, one of which is inertial and the other one is not. Your argument is therefore meaningless in this context, because we are not comparing two symmetric frames in relative motion, that is why acceleration is important "all of a sudden".

Btw, if you compare two purely inertial frames, then obviously the acceleration history has no impact on time dilation between the frames, simply because there is no acceleration, otherwise the frames wouldn't be inertial ! The kind of time dilation you find between purely inertial frames if symmetrical, i.e. you can freely interchange the frames without changing the physical outcome. Not so in the "twin paradox" scenario - you cannot interchange the frames, because they are physically distinguishable due to the presence of acceleration in one of them. That is the whole point.

So, to sum up :

1. Time dilation between inertial frames is a function of their relative velocity only, and has nothing to do with acceleration. Proper time between two given events A and B is an invariant, so all observers will agree on it, regardless of their state of relative motion.
2. Time dilation between inertial and non-inertial frames does depend on acceleration history, and the proper times here are no longer the same for all observers. That is why the travelling twin measures a shorter proper time than the stationary twin.

Also, acceleration and the presence of a gravitational field are physically indistinguishable as per the equivalence principle; "non-gravitational acceleration" is a term that makes little physical sense.

 

[Tach]

So you keep baiting and flaming and pretend to the high ground in some way based on your mistakes? Is that a new way of "doing science" which you recommend to newbies here?

But you are not a "newbie", you are "RealityCheck" sockpuppet. You have been trolling this forum for a long time under the "RealityCheck" name (until you got banned).
Beer w/Straw got your number, so did many others.

 

[ash64449]

What do you mean by the word "invariant"?

invariant means dosen't change