|
Post by Progenitor A on Oct 5, 2010 19:59:00 GMT 1
But I have given you the Cambridge formula No you haven't. You have not said how F is calculated. And it is odd that you call it "field strength", not "acceleration due to gravity". Please provide a link to the website where you got your formula from. Oh my God! Another squabble starting!
|
|
|
Post by eamonnshute on Oct 5, 2010 20:44:03 GMT 1
WUM
|
|
|
Post by carnyx on Oct 5, 2010 21:49:21 GMT 1
olmy. You appear to have lost your rag. To restore it, I suggest you look at the situation with two of your springbobs. When they are together, they will vibrate at the same frequency and so their phases will be the same. If you moved one of these 'clocks' to a different place where 'g' was different, (either millions of miles away, so as to reduce the 'g'' force, or by placing it in an accelerating reference frame .. such as a centrifuge..to increase the G force, you will find that its phase will change. In other words, this 'clock' will show a different time than the static one.
It may be worth saying that Einsteins's view was that clocks that are futher away from earth run faster, and clocks closer run slower. He also said that this will happen with accelerations of any kind because they are indistinguishable from accelerations due to gravity (e.g. 'g')
So, as Newton defined the strength of acceleration due to 'g' in terms of the inverse square of distance between masses (and so, the shape of the gravitational field), the fact that any accelerating clock will slow down relative to one that is accelerating at a slower rate, is integral to Newton's wolrd-view.
@sta,
I hope you too can contemplate Einsteins's rule of equivalence;
" It is not possible to distinguish between the force due to acceleration, and the force due to gravity"
Then, could you tell me what, exactly, you mean by a gravitational field, and how you would measure and map it?
abacus9900
As I said earlier, 't' is a relative count between two chains of events. In other words, how can you measure (e.g.quantise) the interval between two events?.. and the answer is .. only by reference to a counting of events in another chain of events. This search for ever-faster chains of events that we can detect and count ( i.e to quantise) gets us to physical measurement limits, both of the minimum energy level needed to communicate an event, and so distance. Beyond that limit is the world of quantum physics, where we can not be entirely sure of things, so we have to start using probabilities. So 't' is always going to stay as a relative counting between events, and I suppose you could find the smallest lump or quantum of 't' .. or 'event' that it is possible for us to resolve. I guess it would have to be expressed in distance travelled by light, as we have no faster means of communication just yet.
(As a digression, and talking of the smallest packet of energy, I find if fascinating that the unaided human eye is actually capable of detecting just one photon)
|
|
|
Post by abacus9900 on Oct 5, 2010 22:03:08 GMT 1
So, you are talking about correlations. Do you think that what we regard as causal events are really just coincidences that are somehow predetermined?
|
|
|
Post by olmy on Oct 5, 2010 22:17:48 GMT 1
When they are together, they will vibrate at the same frequency and so their phases will be the same. If you moved one of these 'clocks' to a different place where 'g' was different, (either millions of miles away, so as to reduce the 'g'' force, or by placing it in an accelerating reference frame .. such as a centrifuge..to increase the G force, you will find that its phase will change. In other words, this 'clock' will show a different time than the static one. Time dilation is not about absolute time (phase), it's about durations (period or frequency). I've given you the formula for that. The formula is exactly equivalent to the one you used for the pendulum. You pointed to the g in that to support your fruit-loop 'theory'. It is not in the spring formula. You can't have it both ways. You are simply wrong. ...the fact that any accelerating clock will slow down relative to one that is accelerating at a slower rate, is integral to Newton's wolrd-view. Piffle.
|
|
|
Post by olmy on Oct 5, 2010 22:25:53 GMT 1
Cambridge UniversityT’=T(1 + F/c 2) where T' = dilated time T= reference time F= gravitational field strength c= speed of light Thus if F is a weak field, little time dilation occurs If F is a strong field then more dilation occurs I wonder why you didn't give the link (not). You can find it here - in the pdf for "General Relativity"... www.damtp.cam.ac.uk/user/tong/concepts.htmlThe 'F' appears as a Phi (p14) and refers to potential, just like Speaker said. If you doubt that, go to page 15, where Phi is given for a point mass as -GM/r, then consult... en.wikipedia.org/wiki/Gravitational_potential#Mathematical_form
|
|
|
Post by carnyx on Oct 5, 2010 23:06:32 GMT 1
olmyYou seem to be having difficulty with the implications of a change of phase, i.e. that it is also a change of frequency, and also of pulse-length, and also period, and in a clock..a change of 't' (BTW it is amusing to see you dismissing Einstein's thinking, as 'piffle' ) abacus9900Time-as-a-flow is not an independent physical property. 't' is a relative measurement, a correlation if you will, between two separate chains of events. Try this one; How can you prove that the intervals between successive ticks of a clock are the same? (i.e. that the clock can be used to measure 't' ?)
|
|
|
Post by Progenitor A on Oct 6, 2010 7:08:30 GMT 1
|
|
|
Post by olmy on Oct 6, 2010 7:46:25 GMT 1
You seem to be having difficulty with the implications of a change of phase, i.e. that it is also a change of frequency, and also of pulse-length, and also period, and in a clock..a change of 't' Drivel. Phase is quite independent of period. Take a look at: en.wikipedia.org/wiki/Simple_harmonic_motionYou have no grasp even of basic Newtonian mechanics and yet you want to tell every one else that Einstein was wrong. (BTW it is amusing to see you dismissing Einstein's thinking, as 'piffle') Einstein was right. You are wrong. The problem is that you don't understand either Newtonian mechanics or Relativity. I really don't know why so many people seem to think that they can tell everyone else about how the universe works when they can't even tackle the most basic of scientific problems themselves... It sort of comical, in a tragic sort of way. A bit like some who struggles to understand a child's construction set trying to tell the world's aerospace engineers that they don't know how to design aircraft...
|
|
|
Post by olmy on Oct 6, 2010 7:56:15 GMT 1
Did you wonder what that funny point-down triangle symbol was that relates the two...? It's a vector differential operator. The acceleration arises from the gradient of the potential. If you read on in the wiki link, it explains this... "The gravitational field, and thus the acceleration of a small body in the space around the massive object, is the negative gradient of the gravitational potential." en.wikipedia.org/wiki/Gravitational_potential
|
|
|
Post by Progenitor A on Oct 6, 2010 8:15:25 GMT 1
What she's referring to is the gravitational potential, which is a measure of the stored energy in an object which is a direct measure of the amount of energy required to place an object in a given position above the earth. The original energy required had to oppose the gravitation force, therefore, gets stored in an object and when released, such an object falls towards the earth by expending kinetic energy. Well, it is unclear what she means by gravitational potential She could mean, as you say the potential energy of a mass in a gravitational field Or she could mean the definition of gravitational potential which is that force required to move a mass so that it is not affected by another mass's gravitational field There is similarity between the two, but also an essential difference. For example in the uniform gravitational field as STA has defined it( Constant accelerating force unrelated to distance) a mass can never escape the gravitational field of another mass and the gravitational potential is infinite. Of course in a real gravitational filed the amount of work needed to move a mass away from another decreases in proportion to the inverse square of the distance to be moved. However, assuming that STA means potential energy (which in a uniform gravitational field [as defined by STA] never decays as distance increases), here is a thought experiment Remember that STA maintains (I think) that time dilation is due to gravitational potential energy, and that is simply a function of a mass moving a distance against a restraining force. hence in a gravitational filed if identical masses are at heights h1 and 2h1 then one mass has twice the potential energy of another (and according to STA the higher mass has less time dilation than the lower mass) Now here is the thought experiment A simple square strong frame is constructed on gravity-free space(this experiment can also be conduced in a gravitational field). Two springs with clocks attached to one end are stretched and hooked to the frame. One spring is weak, the other strong. Both springs are stretched to the full extent of the frame. The potential energy of the strong spring is much greater than the weak spring. There is a big difference between their potential energies Does the clock on the strong spring run slower than the clock on the weak spring?
|
|
|
Post by Progenitor A on Oct 6, 2010 8:35:03 GMT 1
You seem to be having difficulty with the implications of a change of phase, i.e. that it is also a change of frequency, and also of pulse-length, and also period, and in a clock..a change of 't' Drivel. Phase is quite independent of period. Hi Carnyx This guy appears to not read properly what you have said frequency =d(phase)/dt If the rate of phase changes so does frequency If the frequency changes so does the period If there is a 'jump' in phase, the rate of phase change has changed and new fgrequencies arise. If the same clock is moved to a different gravitaional field and a phase change occurs, then new frequencies have popped up. Just as you said In an oscillating suspended spring, gravity affect the oscillation periods in that the weaker the gravitational force the more rapid the decay of oscillation - the stronger the gravitational force the slower is the decay of oscillation. Hence there are multiple frequencies present in such an oscillating spring - the basic mode and higher frequencies and the weaker the gravitational field the higher are the amplitudes of higher frequences compared to the basic mode. In timing applications these higher frequencies (shorter periods) will interfere with the basic mode making timing less reliable unless they are filtered out.
|
|
|
Post by olmy on Oct 6, 2010 9:02:58 GMT 1
This guy appears to not read properly what you have said frequency =d(phase)/dt If the rate of phase changes so does frequency If the frequency changes so does the period Oh, the irony! Look, simple harmonic motion (pendulums and spring oscillators) is defined by x(t) = A cos(wt + phi) Where w = 2 pi times frequency. en.wikipedia.org/wiki/Simple_harmonic_motionThe period (do either of you know any trigonometry, what 'cos' means?) is defined entirely by w. You can tell that by the fact that it is the bit that is multiplied by time. The phase is phi. The phase depends on the initial conditions... "The frequency of the motion is determined by the intrinsic properties of the system (often the mass of the body and a force constant), while the amplitude and phase are determined by the initial conditions (displacement and velocity) of the system. " -- From the above link. The sort of pseudo-time dilation that carnyx is trying to argue for would need a change in w, which, in the case of the spring (but not in the case of the pendulum) does not depend on the acceleration due to gravity (g).
|
|
|
Post by Progenitor A on Oct 6, 2010 9:17:32 GMT 1
Hi again Carnyx
This guy simply does not read what is written!
Phi, a phase angle is measured in degrees Frequency is d(phi)/dt
Hence if d(phi) = 2pi and dt =1 sec, then frequency =1Hz!
If d(phi)/dt changes so does frequency.
Perhaps he is being deliberately obtuse?
|
|
|
Post by olmy on Oct 6, 2010 9:28:52 GMT 1
Hi again Carnyx This guy simply does not read what is written! Phi, a phase angle is measured in degrees Frequency is d(phi)/dt Hence if phi = 2pi and dt =1 sec, frequency =1Hz! If d(phi)/dt changes so does frequency. Perhaps he is being deliberately obtuse? Oh, for goodness sake! If you actually spend a tiny bit of time thinking, it would help. Fine, if you want to use none-standard terminology in this context, we can call the instantaneous 'phase' the entire 'angle'. In simple harmonic motion, in that case, the 'phase' will be ph = wt + phi Then, guess what? d(ph)/dt = w. I will repeat the point.... The sort of pseudo-time dilation that carnyx is trying to argue for would need a change in w, which, in the case of the spring (but not in the case of the pendulum) does not depend on the acceleration due to gravity (g). Get it now or do you want to expose your ignorance even more....?
|
|