If t=0 the d=0 dilemma?

[Quantum Quack]

"If it rains then I get wet" does not imply that "if it does not rain, then I don't get wet".

you are referring to rain in both cases or is the second case referring to some other source of wetness?


How is movement and distance unrelated?

 

[AlexG]

How is movement and distance unrelated?

The distance exists whether you move along it or not.

 

[CptBork]

When we take an arbitary moment on any time line we can claim that to be t=0 but in doing so in Minkowski/Einstein space time this means that any distance at t= 0 must be also zero.

"Minkowski/Einstein" (flat) spacetime doesn't imply that.

and it is this basic logic that I am trying to sort out.

There's no logic to your argument, that's why you're having trouble sorting it out.

 

[keith1]

...
When we take an arbitary moment on any time line we can claim that to be t=0 but in doing so in Minkowski/Einstein space time this means that any distance at t= 0 must be also zero. ...

Stop! You are not only taking "an arbitrary moment on any time line", you are doing so with "an arbitrary measurement device". You cannot do that Q.Q. That is not allowed.
(See: Uncertainty principle)

 

[funkstar]

you are referring to rain in both cases or is the second case referring to some other source of wetness?

That really, really doesn't matter: The reasoning is still unsound. You've committed a basic logical error. Basically, denying the antecedent. This is in addition to the basic "time implies distance" error.

How is movement and distance unrelated?

I didn't say unrelated, I said different. And they clearly are: Distance has to do with metrics, and movement with dynamics. Metrics are not dependent on dynamics.

 

[AlphaNumeric]

indeed there is no instant of time as light must move a single Planck length.

The Planck time and Planck length are not 'smallest steps', they are the time and length whereby if you want to consider smaller amounts you must include quantum gravity as they signify the sizes at which the gravitational coupling becomes non-perturbative.

so using t=0 to define any given moment is falacious is it not?

No, 't=0' is the physicist way of saying something like "It happened at 5 o'clock". For instance, "Let $$\dot{x} = 0$$ at t=0" is like saying "Initially the ball isn't moving".

When doing something like defining boundary conditions at a particular time what is being done is defining the configuration of a system at a given moment so that we then consider how that changes as time progresses, the system in question can have spatial extension. Space-time is 4 dimensional (usually), which means you need to give 4 coordinates to define a point in it (where and when something happened). Giving only the time component only narrows things down by a 3 dimensional region (you know when but not where). Saying "Let t=T" is a physicist way of defining a space-like hypersurface in space-time, a snapshot of the universe (or whatever system you're looking at).

As the smallest time duration can be is a Planck length. Science is saying that time duration can never be zero.

You should really look up what science says. This is precisely what my previous post was getting at, you don't do even the smallest amount of reading and then you simply assert things based on your ignorance and refuse to listen to anything which doesn't reinforce that. That is the epitome of intellectual laziness and dishonesty.

just wanting to be clear that any given t= 0 is deemed ludicrous by science. According to Keith1's reference to Planck [at least]

Here's a thought, why don't you look up what science says rather than taking someone else's word for it in a thread you started to whine about your misunderstandings of said thing you haven't bothered to read up on.

One can then conclude that the hyper surface of the present as modelled by SRT is indeed a Planck length in time duration.

Firstly, t=T defines a hypersurface in any multdimensional system, be it Newtonian space and time, special relativity space-time, general relativity space-time or abstract spaces like polynomial varieties or moduli Kahler manifolds.

Secondly, special relativity has no notion of the Planck scale since it doesn't include gravity and the Planck scale is defined by gravitational phenomena.

Thirdly even if the Planck time scale were the smallest possible time what it would mean is that if you are letting time 'flow' then you can only do it in steps integer multiples of the Planck time. t=0 is still fine but the next value of the time parameter you'd be allowed to consider would be $$t = T_{\mathrm{Pl}}$$, but not $$t = \frac{1}{2} T_{\mathrm{Pl}}$$.

because for sure SRT would be impossible if t=0 duration as distance would also be zero.

I've already corrected you on this (and not just in this thread). An instant in time means things are 'locked' in place but that doesn't mean distance is zero, just things aren't traversing any distance. At any instance in time the Earth is around 190 million miles from the Sun. Just because in an instant you can't use a physical process to do an actual measurement doesn't mean the distance isn't there. More formally, distances on the hypersurface defined by t=T are still well defined. In fact special relativity is a particularly simple example of this because its metric is constant (unlike many cases in GR) in both space and time. Given a metric g the length s of a curve $$x^{a}(\lambda)$$ for $$0 \leq \lambda \leq 1$$ is obtained from the Pythagorian formula $$ds^{2} = g_{ab}(x) \,dx^{a}dx^{b}$$ and thus

$$s = \int_{0}^{1} \sqrt{g_{ab}\frac{\partial x^{a}}{\partial \lambda}\frac{\partial x^{b}}{\partial \lambda}} d\lambda$$.

The $$\lambda$$ is not a time parameter, it is a parameterisation of the curve. Its often convenient to view it as akin to time but only when you're considering particular kinds of curves (time-like ones, as the name suggests). The length is defined by the curve and the metric. The metric is, in full generality, dependent on space-time position but for SR it isn't, g(x) = g(y) for all x,y in Minkowski space-time. As a result s is independent of time :

$$s = \int_{0}^{1} \sqrt{-\frac{\partial x^{0}}{\partial \lambda}\frac{\partial x^{0}}{\partial \lambda} + \frac{\partial x^{i}}{\partial \lambda}\frac{\partial x^{i}}{\partial \lambda}} d\lambda$$.

t doesn't enter into this at all so its value, fixed or not, is irrelevant. I've explained this to you before but you obviously didn't understand and have made no attempt to understand since.

Using a plank length may complicate things but doesn't change the basic dillemma any ways...

The basic dilemma is you don't understand and so you're trying to convince yourself (because you're sure not convincing anyone who can do relativity) that its okay you don't understand because its all wrong. This is the motivation behind most cranks, they don't understand something and so conclude it must be wrong, else they'd understand it. Look at Motor Daddy, he struggles with the notion of reference frame yet harps on about relativity. Likewise for Geist and you. Farsight aims even higher, trying his best to convince people pretty much all quantum and relativistic stuff from the last century was in some way wrong. And not one of you displays a competency in anything you complain about.

 

[Motor Daddy]

Look at Motor Daddy, he struggles with the notion of reference frame yet harps on about relativity. Likewise for Geist and you. Farsight aims even higher, trying his best to convince people pretty much all quantum and relativistic stuff from the last century was in some way wrong. And not one of you displays a competency in anything you complain about.

I'd appreciate it if you didn't mention my name in threads I'm not participating in. If you disagree with my logic (and I do mean logic) then by all means, I invite you to the thread we are discussing things. Tell me why I'm wrong instead of talking behind my back in a thread I'm not participating in.

 

[Quantum Quack]

That really, really doesn't matter: The reasoning is still unsound. You've committed a basic logical error. Basically, denying the antecedent. This is in addition to the basic "time implies distance" error.

I didn't say unrelated, I said different. And they clearly are: Distance has to do with metrics, and movement with dynamics. Metrics are not dependent on dynamics.

It would be "denial of the anticedent" only if the anwser to the question raised is already known by myself [ which of course it wasn't].

I was obviously working on the invalid premise that time and distance are directly and exclusively related in Minkowski/Einstien Space time and due to this error of understanding have made, according to those who know that it is an error, a "denial of anticedent"
However from my erroneous perspective it was not, but of course it is now.

Regardless, thanks for pointing it out to me.

 

[AlphaNumeric]

I'd appreciate it if you didn't mention my name in threads I'm not participating in.

So I'm not allowed to make reference to anyone who isn't in a thread? Does that mean we're not allowed to reference people like Einstein or Hawking, as they aren't here either?

If you disagree with my logic (and I do mean logic)

No, you don't. You simply assert things without evidence (or even in the face of contradicting evidence) and fail to provide reasoned arguments. When you start disagreeing with experiments its time to either stop BS'ing and admit you're wrong.

It seems more often than not hacks aren't trying to convince others, they are trying to convince themselves of the validity of their claims, perhaps as a way of squaring the facts they don't understand some part of science with their self delusion they couldn't possibly not be capable of understanding something someone else can. You and Farsight have been indulging in such things in some of the more lengthy threads currently on the first page so I mentioned you by name. Anyone whose been here long enough will know precisely what I'm referring to. And its not like I'm doing it 'on the sly', this is in the same subforum as threads you are posting in and you obviously read this thread too. Besides, what are you going to defend yourself with, the same clap-trap as in all your other threads? You've already had plenty of corrections and explainations provided to you, a few of them by me, and if you had anything new to use to defend your assertions you'd have provided it in the other thread so its not like you'll come up with a new defence of your assertions for this thread.

then by all means, I invite you to the thread we are discussing things.

Many people already have. I have in the past. You display the same behaviour as QQ or Farsight (hence why I mentioned you), you just assert things, without evidence or even in the face of evidence, and you incorrectly paraphrase things you denounce because its quite clear you haven't bothered to take the time to understand them.

Tell me why I'm wrong instead of talking behind my back in a thread I'm not participating in.

JamesR is obviously willing to engage in discussion with you, he's presented plenty of explanations about your flawed understanding and yet you haven't taken them on board. It took something like 30 pages to get you to even grasp the concept of a reference frame in a vacuum or anything else for that matter.

You've demonstrated you aren't interested in honest informed discussion so why should I bother when you've shown you'll just ignore anything which doesn't match your preconceptions? I've already spent a fair amount of time explaining to Farsight his mistakes about curvature, so I don't really fancy spending more time on another person with the same sort of mental block. JamesR is doing a good job blowing your arguments apart, I'm not needed to point out your mistakes

 

[Quantum Quack]

The Planck time and Planck length are not 'smallest steps', they are the time and length whereby if you want to consider smaller amounts you must include quantum gravity as they signify the sizes at which the gravitational coupling becomes non-perturbative.

No, 't=0' is the physicist way of saying something like "It happened at 5 o'clock". For instance, "Let $$\dot{x} = 0$$ at t=0" is like saying "Initially the ball isn't moving".

When doing something like defining boundary conditions at a particular time what is being done is defining the configuration of a system at a given moment so that we then consider how that changes as time progresses, the system in question can have spatial extension. Space-time is 4 dimensional (usually), which means you need to give 4 coordinates to define a point in it (where and when something happened). Giving only the time component only narrows things down by a 3 dimensional region (you know when but not where). Saying "Let t=T" is a physicist way of defining a space-like hypersurface in space-time, a snapshot of the universe (or whatever system you're looking at).

You should really look up what science says. This is precisely what my previous post was getting at, you don't do even the smallest amount of reading and then you simply assert things based on your ignorance and refuse to listen to anything which doesn't reinforce that. That is the epitome of intellectual laziness and dishonesty.

Here's a thought, why don't you look up what science says rather than taking someone else's word for it in a thread you started to whine about your misunderstandings of said thing you haven't bothered to read up on.

Firstly, t=T defines a hypersurface in any multdimensional system, be it Newtonian space and time, special relativity space-time, general relativity space-time or abstract spaces like polynomial varieties or moduli Kahler manifolds.

Secondly, special relativity has no notion of the Planck scale since it doesn't include gravity and the Planck scale is defined by gravitational phenomena.

Thirdly even if the Planck time scale were the smallest possible time what it would mean is that if you are letting time 'flow' then you can only do it in steps integer multiples of the Planck time. t=0 is still fine but the next value of the time parameter you'd be allowed to consider would be $$t = T_{\mathrm{Pl}}$$, but not $$t = \frac{1}{2} T_{\mathrm{Pl}}$$.

I've already corrected you on this (and not just in this thread). An instant in time means things are 'locked' in place but that doesn't mean distance is zero, just things aren't traversing any distance. At any instance in time the Earth is around 190 million miles from the Sun. Just because in an instant you can't use a physical process to do an actual measurement doesn't mean the distance isn't there. More formally, distances on the hypersurface defined by t=T are still well defined. In fact special relativity is a particularly simple example of this because its metric is constant (unlike many cases in GR) in both space and time. Given a metric g the length s of a curve $$x^{a}(\lambda)$$ for $$0 \leq \lambda \leq 1$$ is obtained from the Pythagorian formula $$ds^{2} = g_{ab}(x) \,dx^{a}dx^{b}$$ and thus

$$s = \int_{0}^{1} \sqrt{g_{ab}\frac{\partial x^{a}}{\partial \lambda}\frac{\partial x^{b}}{\partial \lambda}} d\lambda$$.

The $$\lambda$$ is not a time parameter, it is a parameterisation of the curve. Its often convenient to view it as akin to time but only when you're considering particular kinds of curves (time-like ones, as the name suggests). The length is defined by the curve and the metric. The metric is, in full generality, dependent on space-time position but for SR it isn't, g(x) = g(y) for all x,y in Minkowski space-time. As a result s is independent of time :

$$s = \int_{0}^{1} \sqrt{-\frac{\partial x^{0}}{\partial \lambda}\frac{\partial x^{0}}{\partial \lambda} + \frac{\partial x^{i}}{\partial \lambda}\frac{\partial x^{i}}{\partial \lambda}} d\lambda$$.

t doesn't enter into this at all so its value, fixed or not, is irrelevant. I've explained this to you before but you obviously didn't understand and have made no attempt to understand since.

The basic dilemma is you don't understand and so you're trying to convince yourself (because you're sure not convincing anyone who can do relativity) that its okay you don't understand because its all wrong. This is the motivation behind most cranks, they don't understand something and so conclude it must be wrong, else they'd understand it. Look at Motor Daddy, he struggles with the notion of reference frame yet harps on about relativity. Likewise for Geist and you. Farsight aims even higher, trying his best to convince people pretty much all quantum and relativistic stuff from the last century was in some way wrong. And not one of you displays a competency in anything you complain about.

now if I am not mistaken that is a fantastic post, on behalf of the readers and myself [ including all the cranks] , thanks!