No, I compared c transit times to curved space and flat space - sorry if it came across as ‘direct route’ in curved space time.
The point was if light has to go around a massive body that is distorting space, it will take longer than if that body wasn’t there, and spacetime was therefore flat.
A thought experiment. Imagine a cube of arbitrary size hurtling through the cosmos. I could measure the size of the cube by measuring the transit time from a corner of the cube to the edges to get t(x,y,z). How would that cube relate then to what we call passing time? Is it that td(x,y,z) (td for cube size) are fixed in relation to each other but tr time (for time relative) is simply c‘s transit time to an arbitrary relative reference to td(x,y,z)?
The point was if light has to go around a massive body that is distorting space, it will take longer than if that body wasn’t there, and spacetime was therefore flat.
A thought experiment. Imagine a cube of arbitrary size hurtling through the cosmos. I could measure the size of the cube by measuring the transit time from a corner of the cube to the edges to get t(x,y,z). How would that cube relate then to what we call passing time? Is it that td(x,y,z) (td for cube size) are fixed in relation to each other but tr time (for time relative) is simply c‘s transit time to an arbitrary relative reference to td(x,y,z)?
I see it more predicts effects but in practice has little to do with realisation. Also pointing out the entangled mess behind the Dirac work I linked to. 😉 My hero as he came up with an idea that I call a Dirac pulse.
Correct but does the term Space Time help or confuse. Time is often referred to as an arrow. Something "space" moves along and the "rate" is effected by gravity. EMR is also effected by gravity but isn't the yardstick used to measure that also time? Plus deflection of course. That is bending 3D space or is it - gravity attracts things.
Many people link space-time with Albert Einstein, who proposed special relativity in 1905. However, it was Einstein's teacher, Hermann Minkowski, who suggested space-time, in a 1908 essay.
I think that is the point I'm pondering. If you accelerate a body in free space at 1G where there is no gravity, it will feel forces that are no different from those it would experience if placed on the surface of the Earth - this was one of Einstein's great thought experiments.
However, how does a body in deep space experience mass? You can think of it as the body having its time relationship to everything else in the universe being shifted while it undergoes acceleration. During that process, energy is dissipated to create the accelerative force that enables the object's time relationship to be moved. When the accelerating force is removed, the body is once again weightless, but it has a new set of time relationships compared to what it had before. It will, of course, have new momentum/velocity and will simply coast along until acted upon by another force.
In summary, a change in time relationships was brought about by energy dissipation (to generate the force).
The same accelerative forces are taking place on the Earth and every other large clump of matter in the cosmos. You have matter which has atoms and molecules getting moved around by heat and by atomic energy (electrons moving around nuclei etc) and all of these forces add up to have the same net effect - time is being generated and that's what is perhaps warping the space around a large body, and it affects mass.
All of this of course begs the question: how is the Higgs field involved in this? I wonder what Einstein would have made of it?
However, how does a body in deep space experience mass? You can think of it as the body having its time relationship to everything else in the universe being shifted while it undergoes acceleration. During that process, energy is dissipated to create the accelerative force that enables the object's time relationship to be moved. When the accelerating force is removed, the body is once again weightless, but it has a new set of time relationships compared to what it had before. It will, of course, have new momentum/velocity and will simply coast along until acted upon by another force.
In summary, a change in time relationships was brought about by energy dissipation (to generate the force).
The same accelerative forces are taking place on the Earth and every other large clump of matter in the cosmos. You have matter which has atoms and molecules getting moved around by heat and by atomic energy (electrons moving around nuclei etc) and all of these forces add up to have the same net effect - time is being generated and that's what is perhaps warping the space around a large body, and it affects mass.
All of this of course begs the question: how is the Higgs field involved in this? I wonder what Einstein would have made of it?
I think I can show it's a longer path and takes more time with a thought experiment.
Suppose a ray of light from a nearby star goes halfway through the galaxy (big inverse-square losses but bear with me), goes around a black hole (doing an approximate 180), comes back to Earth and we see it. Does that take a longer time than the light that comes to us directly from the star?
That statement is back to front in terms of elementary physics, as I will demonstrate below.
(Remember we are talking about "deep space" where there are no gravitational influences.)
If a mass is acted upon by an unbalanced force it will undergo an acceleration in the direction of the unbalanced force.
During the period during which the unbalanced force is applied the mass will gain kinetic energy.
Energy is not "dissipated" to "create" the acceleration force. The fact is that the unbalanced force, by doing work against the inertia of the mass, converts chemical energy (in rocket fuel presumably) to kinetic energy.
The words "dissipate" and "create" are totally inappropriate in this discussion since energy can neither be created nor destroyed, but can only be converted from one form to another.
Last edited:
Fair enough, the terms are inappropriate in a formal physics sense and I accept that. I should have worded that more carefully.
It does not change the fact that in converting one form of energy into another, inertia and momentum were involved, or that the object's time references were changed which is the point I was making.
It does not change the fact that in converting one form of energy into another, inertia and momentum were involved, or that the object's time references were changed which is the point I was making.
Thanks for your response to my question, but I was thinking more in terms of how "local curvature" might affect the transit time of light past a star.
By the way Galu, that statement of mine does not imply that energy is lost or destroyed. After all, heat sinks get hot because heat energy is dissipated by the output devices so you are exchanging electrical energy for heat energy.
🙂
You know exactly what it means Galu, because we've discussed using c as a cosmic ruler enough times on the thread!
Let us assume two objects are moving next to each other in space. I then measure the time difference between the two objects wrt each other I note that it is not changing between them, although it will be changing to a 3rd object that is not moving with them. If I accelerate one of the original two objects away, the time difference between the two objects will change (and possibly with the 3rd). So the original two objects' time reference (call it difference if that feels more comfortable) has changed wrt each other and with the 3rd object (All times relative of course).
Dirac was difficult: https://www.npr.org/2009/10/02/113435529/physicist-paul-dirac-is-the-strangest-man
But clearly gifted. 🙂
If you want to talk about General Relativity in a General Way, you cannot omit Amelie Noether:
https://en.wikipedia.org/wiki/Emmy_Noether
I, of course, am an Information Theorist with a Constantinides Number of 1:
https://en.wikipedia.org/wiki/Claude_Shannon
All is Information:
TBH, I just made that up. We never published a paper together, but I did attend some of his entertaining courses on Digital Signal Processing at I.C. Nor with Alan Turing:
https://en.wikipedia.org/wiki/Alan_Turing
Another flippin' Genius. Cambridge, the Light Blues, of course. The Home of Mathematics. Why 5, 8 and 24 are the best numbers in the Universe:
https://www.scientificamerican.com/article/octonions-web-exclusive/
🙂
But clearly gifted. 🙂
If you want to talk about General Relativity in a General Way, you cannot omit Amelie Noether:
https://en.wikipedia.org/wiki/Emmy_Noether
I, of course, am an Information Theorist with a Constantinides Number of 1:
https://en.wikipedia.org/wiki/Claude_Shannon
All is Information:
TBH, I just made that up. We never published a paper together, but I did attend some of his entertaining courses on Digital Signal Processing at I.C. Nor with Alan Turing:
https://en.wikipedia.org/wiki/Alan_Turing
Another flippin' Genius. Cambridge, the Light Blues, of course. The Home of Mathematics. Why 5, 8 and 24 are the best numbers in the Universe:
https://www.scientificamerican.com/article/octonions-web-exclusive/
🙂
Last edited:
Britannica has a run down on him
https://www.britannica.com/biography/Paul-Dirac
Can't copy paste from it. Interesting comment about methods of cancelling infinities and his feelings about it.
Let's examine what "using c as a cosmic ruler" might mean.
In spacetime there is no separate space and time.
Space and time may be regarded as just two different directions in the continuum called spacetime.
As they are the same thing, there is no requirement to use different units for space and time.
Since the speed of light c is an absolute, if we replace time (t) with c times time (ct) we can replace time in seconds with time in metres.
By that reckoning, 1 second would be ~ 3 x 10^8 metres.
So, in spacetime, distance and time units are the same, which is counterintuitive to our normal understanding of these two quantities in our everyday lives.
Words are fascinating. Humpty Dumpty talked about them, and there was that thing on the radio when I was a teen: "there's a sign on the wall, but she wants to be sure ..."
Welcome to the forum, and thanks for the opinion expressed in this, your first, post.
However, although the orbits of quarks in nucleons can account for the electromagnetic force and the strong nuclear force, I can find no mention of a link with gravity in other scientific publications.
Keep reading - there's a lot more to contemplate in this thread!
Anything that has mass also generates it's own gravity field. That seems to be generally accepted.
That has nothing to do with the premise of the abstract that started off this thread.