Questions about time

[edd]

Well said Dazza. If I might digress a little, one of the most important symmetries IMHO is that between momentum and inertia. Maybe that ought to be energy-momentum with the word kinetic thrown in too, or it might be better to talk about a symmetry between energy and mass as per Einstein's E=mc² paper. But anyway and in simple terms, momentum is resistance to change-in-motion when you're trying to slow something down, whilst inertia is resistance to change-in-motion when you're trying to speed it up.

Errr no.

And I don't think you're using 'symmetry' in quite the same way as theoretical physicists are.

 

[DazzaD]

Errr no.

And I don't think you're using 'symmetry' in quite the same way as theoretical physicists are.

Yes that was not quite what I meant Farsight .. I meant in a stricter mathematical sense in set theory... not as in spotting analogous patterns in physics...

 

[Farsight]

No you could not. If we entertain the idea that if the bottom ship "pulls away" from the other two and breaks that pretty pattern... how do you infer from that that it is moving at TWICE the speed of the others? (without knowing anything about time or distance?)

I said the bottom two ships start moving to the right. Then you see this:
______________
_______ ______________
______________ ______________

Also the purpose of a natural system of units is to make the physical constants have a numerical value of one... not the chosen SI unit for it, or any other chosen method of measuring it, but the physical constant itself (considered to be natural in the sense it is outside of human intervention in a theoretical and conceptial sense and not dependent on a chosen 'weirdness' particular to some person)...

All points noted, I said there's a hint, that's all.

 

[sol invictus]

Well said Dazza. If I might digress a little, one of the most important symmetries IMHO is that between momentum and inertia. Maybe that ought to be energy-momentum with the word kinetic thrown in too, or it might be better to talk about a symmetry between energy and mass as per Einstein's E=mc² paper. But anyway and in simple terms, momentum is resistance to change-in-motion when you're trying to slow something down, whilst inertia is resistance to change-in-motion when you're trying to speed it up. And motion is relative. Couple that with Compton scattering and pair production & annihilation and the wave nature of matter, and surely all you're dealing with is trying to alter a free-running wave in an open path or a standing wave in closed path. It beats me why this isn't common knowledge after a hundred years, and instead people talk about the mystery of mass and the Higgs boson, when the Higgs mechanism is responsible for only 1% of the mass of matter. Why hasn't somebody turfed the "ad-hoc" Higgs sector out of the standard model and replaced it with another symmetry.

Farsight's posts are like physics Mad Libs.

 

[Kwalish Kid]

Delete

 

[Farsight]

And I don't think you're using 'symmetry' in quite the same way as theoretical physicists are.

Yes that was not quite what I meant Farsight .. I meant in a stricter mathematical sense in set theory... not as in spotting analogous patterns in physics...

Make your mind up Dazza. Decide whether you're talking about Symmetry (physics) or Symmetry in mathematics. Do some careful checking on what you say. Then do some careful checking on the experiments I've referred to, and then do some carful checking of Does the Inertia of a Body Depend Upon Its Energy Content?. I'm not pulling your leg with the mass thing.

 

[Michael C]

But we really do use the motion of light to define both the second and the metre.

Can you define either a second or a metre uniquely in terms of the motion of light?

 

[Tubbythin]

Make your mind up Dazza. Decide whether you're talking about Symmetry (physics) or Symmetry in mathematics. Do some careful checking on what you say. Then do some careful checking on the experiments I've referred to, and then do some carful checking of Does the Inertia of a Body Depend Upon Its Energy Content?. I'm not pulling your leg with the mass thing.

It should be fairly clear that I was talking about this.

 

[Tubbythin]

Well said Dazza. If I might digress a little, one of the most important symmetries IMHO is that between momentum and inertia. Maybe that ought to be energy-momentum with the word kinetic thrown in too, or it might be better to talk about a symmetry between energy and mass as per Einstein's E=mc² paper. But anyway and in simple terms, momentum is resistance to change-in-motion when you're trying to slow something down, whilst inertia is resistance to change-in-motion when you're trying to speed it up. And motion is relative. Couple that with Compton scattering and pair production & annihilation and the wave nature of matter, and surely all you're dealing with is trying to alter a free-running wave in an open path or a standing wave in closed path.

Errrm. Pardon?

 

[Tubbythin]

I don't know if anybody has tried, but there's a hint of it in the c=1 in natural units.

Natural units are defined for convenience, nothing more. Things like
E² = p²c² + m²c⁴become
E² = p² + m² which is less faff.

We don't say it's c=1 "motiuns" or "kilomots" or anything similarly alien. But we really do use the motion of light to define both the second and the metre. See what I said in post #151.

I already responded to that post. The choice of units for v and c in the Lorentz factor is entirely arbitrary so long as you use the same units for both v and c. Please tell me you do actually understand units.

And like I was saying, you work out the time dilation due to relativity velocity by saying v is some fraction of c without having to refer to seconds or metres.

For convenience. You could just as well do it in mm/decade if you wanted to.

 

[Tubbythin]

Ever looked at the Schrödinger equation?

Ever noticed how the left-hand side is related to spatial coordinates and the right-hand side to time?

 

[DazzaD]

Make your mind up Dazza. Decide whether you're talking about Symmetry (physics) or Symmetry in mathematics. Do some careful checking on what you say. Then do some careful checking on the experiments I've referred to, and then do some carful checking of Does the Inertia of a Body Depend Upon Its Energy Content?. I'm not pulling your leg with the mass thing.

Tubbythin beat me to it but I clearly mentioned the mathematics behind the physics and was talking about the conservation laws corresponding to the symmetries of groups as used in particle physics.

In any case, the first paragraph of your Physics Symmetry link says the same thing.

The 'symmetry in maths' and 'symmetry in physics' as you distinguish them are one and the same for me...

http://en.wikipedia.org/wiki/Noether's_theorem

 

[Perpetual Student]

Can you define either a second or a metre uniquely in terms of the motion of light?

It's one of the most telling things about cranks in science that there is no logic or evidence that can deflect them from their ill conceived ideas.
Modern physics is based on defining time and space as both fundamental and quantifiable aspects of the universe. Motion may be fundamental in some philosophic sense -- I don't really know -- but the fact that it is not quantifiable dooms it to remain a secondary or emergent concept. This discussion has no scientific basis and has no other real purpose.

 

[Farsight]

I'm the one supplying the evidence and the logic here. You aren't. Instead you're the one dismissing it.

Can you define either a second or a metre uniquely in terms of the motion of light?

Yes. That's how they are defined. The second is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom". That relates to the NIST Caesium fountain clock where hyperfine transitions emit microwaves. There's a "resonant frequency" which is said to be 9,192,631,770 Hz. To define the second we do something similar to sitting in a boat counting oncoming ocean waves bobbing us up and down. When we get to to 9,192,631,770, we say that's a second, so the frequency is 9,192,631,770 Hz by definition. Then once we've got the second we then define the metre as "the distance travelled by light in 1⁄299,792,458th of a second". That's like saying how far the waves move whilst they bob us up and down 30.66 times. Note that if the waves were to move towards us slower, our second would be bigger, but the metre is unchanged because the slower light and the bigger second cancel each other out. Also note that we use the second and metre to measure the local speed of light, so we always measure 299,792,458 m/s regardless of gravitational potential.

 

[Farsight]

Natural units are defined for convenience, nothing more. Things like
E² = p²c² + m²c⁴...

I'll use this to try to explain something to you.

Couple that with Compton scattering and pair production & annihilation and the wave nature of matter, and surely all you're dealing with is trying to alter a free-running wave in an open path or a standing wave in closed path.

Errrm. Pardon?

Before pair production you've got a massless photon, a mere electromagnetic wave wherein E² = p²c². Afterwards, say that you only just had enough energy to create the electron and positron so they don't fly apart. You're in the rest frame of the electron, and you've got E² = m²c⁴. Then the electron and positron annihilate and it back to E² = p²c². There's a flipflop between the terms. The wave was in an open path moving through space at c. Then it was in a closed path. Then it was in an open path again. It isn't magic, and it isn't mysterious. It's just a change in configuration.

 

[Michael C]

Can you define either a second or a metre uniquely in terms of the motion of light?

Yes. That's how they are defined. The second is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom".[...]

That definition is not in terms of the motion of light. Of course, once we have defined a unit of time, we can define a unit of distance by using the speed of light, using the usual relation between speed, distance and time, but we cannot define a unit of time nor of distance using "the motion of light" alone.

None of you motion fanatics have been able to come up with a way to quantify "motion".

 

[Tubbythin]

I'll use this to try to explain something to you.

Ok...

Before pair production you've got a massless photon, a mere electromagnetic wave wherein E² = p²c². Afterwards, say that you only just had enough energy to create the electron and positron so they don't fly apart.

If the photon only has just enough energy to pair produce, then it will almost certainly Compton scatter instead (or be photo-absorbed). But I'm willing to ignore this fact for the time being.

You're in the rest frame of the electron, and you've got E² = m²c⁴.

Well the total energy of the system is E 2m_ec².

Then the electron and positron annihilate and it back to E² = p²c².

Well, in general, the positron will annihilate with a completely different electron than the one it was produced with but I suppose in the extremely unlikely event that a 1.022 MeV photon pair produces then the same electron and positron might annihilate with each other.

There's a flipflop between the terms.

Well, not really. The only flip-flop is because of the manufactured case of a 1.022 MeV photon. In a real situation (where photon energy is well above the threshold energy) then we have:

Initially:
E² =p₁²c²where p1 is the initial energy of the photon
then after pair production we'd have something like (someone can check this if they like):
E² = (p_e+p_p)c² + 4m_ec²where p_e and p_p are the momenta of the electron and positron respectively and m_e is the (rest) mass of the electron.
Then the electron and positron would fly off and gradually lose energy through interactions with atomic electrons. Then eventually the positron would slow down to close to the velocity of the atomic electrons and annihilate with an atomic electron and we'd have:
E² = (p_a+p_b+p_c)c² where p_a+p_b represent the momenta of the two 511 keV photons and p_c is the sum of all the momenta transferred through collision with atomic electrons by the electron and positron and any any residual momentum the pair-produced electron may have when the positron annihilates.

To summarise, the flip-flopping you talk about only occurs, in principle, if the photon has an energy equal to twice that of the electron rest mass energy. In reality, even when this criterion is met (an extremely rare occurrence) pair production is highly unlikely.
And yet this is meant to underline your whole theory?

The wave was in an open path moving through space at c. Then it was in a closed path. Then it was in an open path again.

Pardon.

It isn't magic, and it isn't mysterious.

It also isn't accurate.

 

[Perpetual Student]

That definition is not in terms of the motion of light. Of course, once we have defined a unit of time, we can define a unit of distance by using the speed of light, using the usual relation between speed, distance and time, but we cannot define a unit of time nor of distance using "the motion of light" alone.

None of you motion fanatics have been able to come up with a way to quantify "motion".

All you will get here is continued obfuscation and deflection -- the tricks of science cranks. One cannot define a unit of motion. Modern physics has defined space and time as fundamental for this very reason, otherwise we would be stuck in the mud of Aristotle's "motion" -- no Newton, no Maxwell, no physics.

 

[Farsight]

That definition is not in terms of the motion of light. Of course, once we have defined a unit of time, we can define a unit of distance by using the speed of light, using the usual relation between speed, distance and time, but we cannot define a unit of time nor of distance using "the motion of light" alone.

That's exactly what we do. Come on, think it through. You're sitting in a gedanken rowboat ready to count the waves passing you by, only I've pressed my gedanken freeze-frame button. So there's no motion. None whatsover. So the waves don't move, the boat doesn't move, you don't move, and electromagnetic propagation doesn't propagate. So you can't think because all the signals in your brain are stopped, and you can't see because light is stopped too. I've stopped motion, not time, and now there is no time. Then when I press my play button you count 9,192,631,770 waves passing you by, then you declare that that's a second and proceed to define the metre and assert that the speed of those waves is 299,792,458 m/s. And when I rewind and press my fast-forward button, you still count 9,192,631,770 waves passing you by, then you declare that that's a second and proceed to define the metre and assert that the speed of those waves is 299,792,458 m/s. It doesn't matter how fast those waves are going, you use them to define your second and your metre, and you always say they're going at 299,792,458 m/s.

None of you motion fanatics have been able to come up with a way to quantify "motion".

You haven't quantified time either. And worse, you haven't really quantified the speed of light. When I show you the Shapiro delay and optical clocks losing synchronisation at different elevations, you explain it away using something that nobody can see. And when I subject you to gravitational time dilation you insist that time's passing slower not light. What time? I can see light moving, but I can't see time passing. There are no motion fanatics. Just people with an eye for what's actually there.

 

[Michael C]

That's exactly what we do. Come on, think it through. You're sitting in a gedanken rowboat ready to count the waves passing you by, only I've pressed my gedanken freeze-frame button. So there's no motion. None whatsover. So the waves don't move, the boat doesn't move, you don't move, and electromagnetic propagation doesn't propagate. So you can't think because all the signals in your brain are stopped, and you can't see because light is stopped too. I've stopped motion, not time, and now there is no time. Then when I press my play button you count 9,192,631,770 waves passing you by, then you declare that that's a second and proceed to define the metre

That definition has nothing to do with the motion of light. It has to do with the transition between two states of a caesium atom. We happen to use this phenomenon for the definition because we have found out that it is particularly stable in time.

and assert that the speed of those waves is 299,792,458 m/s. And when I rewind and press my fast-forward button, you still count 9,192,631,770 waves passing you by, then you declare that that's a second and proceed to define the metre and assert that the speed of those waves is 299,792,458 m/s. It doesn't matter how fast those waves are going, you use them to define your second and your metre, and you always say they're going at 299,792,458 m/s.

Yes, as I already said, once you have produced a definition of the second, you can use the speed of light to define the metre.

You haven't quantified time either

No, I haven't quantified time: it has already been quantified by mainstream science. We use this quantification in a mathematical model of physical events which has proven to be extremely accurate.

And worse, you haven't really quantified the speed of light. When I show you the Shapiro delay and optical clocks losing synchronisation at different elevations, you explain it away using something that nobody can see.

No, it's not "explained away". The mathematical model using the standard x, y, z, t coordinates and the standard concept of reference frames predicts exactly what happens in these cases. It's all perfectly logical.

And when I subject you to gravitational time dilation you insist that time's passing slower not light. What time? I can see light moving, but I can't see time passing. There are no motion fanatics. Just people with an eye for what's actually there.

It all boils down to this: you decide, because you can't see time that it doesn't exist. You decide, because you see things moving, that "motion" does exist. That's all.

I'm still waiting for your mathematical model of reality where "motion" is a fundamental quantity and there is no time dimension.