View Full Version : Time and Light


Quantum Quack
10-21-08, 06:01 AM
Wanting to clarify the time and light issue I drew this diagram that shows a light source [star] and a speckled light field shown as a snapshot.
Every speckle shown can be analoguous with a photon particles position relative to the star.

I have placed in this light field 6 relative Observers all traveling at relative velocity with differring vectors to each other and the light source.


http://zeropointtheory.com/images/stories/images/time/diag01.jpg

The question is do they all share the same Hyper Surface Of The Present ?[t=hsp]

I would think that they do but to do so I think would contradict the issue of non-simultaneity for SRT.

Can it be unambiguously stated that :
"If light speed is invariant no matter where a photon event occurs it must be always at the hyper surface of the present ot t=hsp" [ or something to that effect?]

Care to discuss?
Is there a better way to phrase the question?

BenTheMan
10-21-08, 12:24 PM
What is "hyper surface of the present"?

Isn't "present" defined locally for each observer?

rpenner
10-21-08, 01:18 PM
The content of the SRT includes that observers in relative motion can disagree that events not happening in the same place happen at the same time. Thus there is no absolute Hyper Surface Of The Present.

The Mechanical Universe (http://www.learner.org/resources/series42.html) covers some of these topics.

YouTube demo reel of animations from The Mechanical Universe (http://www.youtube.com/watch?v=bvV0p7BpjEU).

Hat tip to Blake Stacey of Science after Sunclipse (http://scienceblogs.com/sunclipse/2008/10/friday_video_the_mechanical_un.php)

Quantum Quack
10-21-08, 03:40 PM
What is "hyper surface of the present"?

Isn't "present" defined locally for each observer?
According to SRT Yes I guess it is defined locally however as you can see in the image I posted all observers seem to share the same hsp or present moment.

I found to be true then this implies a contra to SRT's non- simultaneity as every light event must occur at the same universal presnt moment and thus the "NOW" is an absolute constant.

http://zeropointtheory.com/images/stories/images/time/diag01.jpg

Can you tell me if the above "speckle" diagram image makes sense to you Ben?

Can you see how every speckle of light must share the same present moment [hsp]

the diagram referred to with regards to the HSP is:
http://zeropointtheory.com/images/stories/images/lightc.png
courtecy wiki

Quantum Quack
10-21-08, 03:55 PM
The content of the SRT includes that observers in relative motion can disagree that events not happening in the same place happen at the same time.
and this is exactly what is in contention.
As shown in the "speckle" diagram 01 (http://zeropointtheory.com/images/stories/images/time/diag01.jpg) all observers regardless of relative Velocity must experience their light events simultaneously. Even though their tick rates are different.
And as the entire universe can be considered as a light field then all light events must happen at the same universal moment making the HSP an absolute constant reagrdless of relative velocity of RF.

SRT forbids the use of an absolute reference frame or aether. However light itself is commony used as an absolute reference frame and although not an aether it certainly could be mistaken for one.

What I would like to determine is how my contention is invalid as I fail to see a flaw in the logic. [ which puts me in a difficult position and at odds with SRT]

rpenner
10-21-08, 04:33 PM
That is addressed in the Demo Reel above, betrween marks 7:00 and 8:03.

Quantum Quack
10-21-08, 05:25 PM
That is addressed in the Demo Reel above, betrween marks 7:00 and 8:03.
no it doesn't address it unfortunately.
It only shows SRT's position on light and time.
I am asking that we review this position.

Using light as the absolute reference frame rather than an object of matter.

I do realise that SRT disallows the use of light as a reference frame and that I guess is what is in contention.
Why is it that the most important part about a light effect model is excluded from being a reference frame?
It is afterall the whole reason for SRT existance, that being the invariance of light.

I shall refer to the image I posted again:

http://zeropointtheory.com/images/stories/images/time/diag01.jpg

Again I ask how the logic or reasoning of a universal t= thsp constant is an unavoidable conclusion.

camilus
10-21-08, 07:16 PM
I have a sort of off topic question, but didnt want to start a whole new thread.

Does light have mass? Doesnt the Einstein's relativistic mass equation require light to be massless?

Reiku
10-21-08, 07:46 PM
I have a sort of off topic question, but didnt want to start a whole new thread.

Does light have mass? Doesnt the Einstein's relativistic mass equation require light to be massless?

Not really Camilus. By theory, light acts as thought it is massless, but their are mathematical equations (designed my i add), that can describe the momentum of a photon even if it is massless for E^2-pc^2=(Mc^2)^2 so M=0 for photons, or any massless particles.

Reiku
10-21-08, 07:47 PM
(And yes... to add) -- Einsteins theory treates the photon as being massless.

camilus
10-21-08, 09:25 PM
Not really Camilus. By theory, light acts as thought it is massless, but their are mathematical equations (designed my i add), that can describe the momentum of a photon even if it is massless for E^2-pc^2=(Mc^2)^2 so M=0 for photons, or any massless particles.

I was talking about this equation:

m = {m_0 \over sqrt{1 - (\frac{v}{c})^2}

obviously, if v=c, then the bottom is zero. as is the case with light.

rpenner
10-21-08, 10:58 PM
The biggest problem with that equation is that it doesn't work in equations like \mathbf{F} = m \mathbf{a}.

\mathbf{F} = \left(
\mathbf{1} +
{
{\mathbf{v}\mathbf{v}^t}
\over
{
1 - ( \frac{v}{c} )^2
}
}
\right) {{m_0 \mathbf{a}}\over{\sqrt{1 - ( \frac{v}{c} )^2 }}} where \mathbf{v}\mathbf{v}^t = {{1}\over{c^2}}\left( \begin{array}{ccc} v_x^2 & v_x v_y & v_x v_z \\ v_x v_y & v_y^2 & v_y v_z \\ v_x v_z & v_y v_z & v_z^2 \end{array} \right).

http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html

// Edit, or:
\mathbf{F} = {{m_0 \mathbf{a}}\over{\sqrt{1 - ( \frac{v}{c} )^2 }}} + {{v}\over{c^2}} {{m_0 \mathbf{v} \cdot \mathbf{a}}\over{ \left(1 - ( \frac{v}{c} )^2 \right) ^{\frac{3}{2}}} }

camilus
10-21-08, 11:00 PM
The biggest problem with that equation is that it doesn't work in equations like F = m a


but it works with F = {dp \over dt} = m {dv \over dt}

rpenner
10-21-08, 11:25 PM
But that's incorrect.

\begin{eqnarray}
F = {{dp}\over{dt}} = {{d(\gamma(v) m_0 v)}\over{dt}} = m_0 ( \gamma(v) {{dv}\over{dt}} + {{d\gamma(v)}\over{dt}} v ) & = & m_0 ( \gamma(v) {{dv}\over{dt}} + {{d\gamma(v)}\over{dv}}{{dv}\over{dt}} v ) \\ & = & ( 1 + {{1}\over{\gamma(v)}} {{d\gamma(v)}\over{dv}} v ) m_0 \gamma(v) {{dv}\over{dt}} \\ & = & ( 1 + {{1}\over{\gamma(v)}} \gamma^3(v) {{v}\over{c^2}} v ) m_0 \gamma(v) {{dv}\over{dt}} \\ & = & ( 1 + \gamma^2(v) {{v^2}\over{c^2}} ) m_0 \gamma(v) {{dv}\over{dt}} \end{eqnarray}

camilus
10-22-08, 12:33 AM
According to wikipedia, http://en.wikipedia.org/wiki/Special_relativity#Force

rpenner
10-22-08, 03:22 AM
Yes. Everyone agrees on F = {{dp}\over{dt}} but since {{dp}\over{dt}} \neq m_0 \gamma a it is generally incorrect to say F = m a when relativity is important.

If you really want to memorize F = m a + m{{\gamma^2 v \cdot a}\over{c^2}}v , that is your privilege. Myself, I find it more useful to memorize p = m_0 \gamma v, since I never attach a relativistic mass to a set of spring scales.

Quantum Quack
10-22-08, 03:26 AM
Given that my post [#7] has yet to be addressed the workings you are showing may actually prove to be irrelevant

rpenner
10-22-08, 03:34 AM
No. The workings I am showing are textbook. The textbook is based on the historical and experimental tests of SRT and theories which are indistinguishable from SRT. Specifically, it is an engineering fact that clocks in orbit cannot be synchronized with clocks on the ground because there can be no agreement on simultanity.

But if you would like to dig below the theory to the experimental backing which the theory currently enjoys, you are in luck:
http://relativity.livingreviews.org/Articles/lrr-2005-5/index.html
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

Quantum Quack
10-22-08, 03:43 AM
No. The workings I am showing are textbook. The textbook is based on the historical and experimental tests of SRT and theories which are indistinguishable from SRT. Specifically, it is an engineering fact that clocks in orbit cannot be synchronized with clocks on the ground because there can be no agreement on simultanity.

But if you would like to dig below the theory to the experimental backing which the theory currently enjoys, you are in luck:
http://relativity.livingreviews.org/Articles/lrr-2005-5/index.html
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html
so I guess that means you are not prepared to address the topic?

BenTheMan
10-22-08, 12:44 PM
Given that my post [#7] has yet to be addressed the workings you are showing may actually prove to be irrelevant

Using light as the absolute reference frame rather than an object of matter.

You can't use light as an absolute reference frame, because it moves with the same speed in all reference frames. Doing so would imply that light has a rest frame, which is not true by postulate.

Bishadi
10-22-08, 01:36 PM
You can't use light as an absolute reference frame, because it moves with the same speed in all reference frames. Doing so would imply that light has a rest frame, which is not true by postulate.

Pretty much the same thing i was told 26 years ago, that light cannot be held upon mass, yet what is a quantum jump?

Where does the photon come from in a decay process?

These are items that Bohr posed to Einstein at the Copenhagan meetings and Einstein lost the debate.

I guess that is why the matrix mechanic threads were removed from this section.....

there is a bias by a few on this site.....

Quantum Quack
10-22-08, 06:04 PM
I have created a web site devoted to this issue amongst other similar.
the link to the relevant article is:
http://zeropointtheory.com/index.php?option=com_content&view=article&id=52&Itemid=61
any comments would be appreciated.:)