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Absolute time and the speed of light

Use this forum to discuss the philosophy of science. Philosophy of science deals with the assumptions, foundations, and implications of science.
Steve3007
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Re: Absolute time and the speed of light

Post by Steve3007 » October 4th, 2018, 1:35 am

Hi Frewah. Good idea to bring life back to this old topic. Whenever a new topic is started in this forum it's usually possible to find an old one that covers very similar subject matter.
Frewah wrote:...The point is that ε and μ are the fundamental properties from which c can be derived.
Yes, absolutely. And a key thing about that is that Maxwell's Equations can be written in the same mathematical form as the equations that describe waves - wave equations. And when that is done, the term that (if they were describing waves) would indicate the speed of the waves is the combinations of ε0 and μ0 as you've said. When this was discovered, the values of ε0 and μ0 as measured by experiments such as those carried out by Faraday gave a value for this speed term equal to the speed of light, as measured by other means.

So this is a classic example of the power of physics to unite phenomena that are previously apparently unrelated. In this case its the strengths of the electric and magnetic fields united together with the speed of light. Who would have thought that experiments involving measuring the size of the forces between magnets and the size of the forces between electrical charges would yield the speed of light! Measured by such means as observing the orbits of the moons of Jupiter. And then, via Special Relativity, the electric and magnetic forces themselves are united (into the single phenomenon of electromagnetism) by observing that magnetism is a relativistic manifestation of the electric force.

The magnetic force is the electric force when the principle of relativity is taken into account.

But a key thing about the discovery that the speed of light emerges from Maxwell's equations (as you've said) is that it emerges as a physical constant. By definition, the concepts of speed and velocity only make sense when we specify what we're measuring that velocity relative to. But the term for 'c' that emerges from Maxwell's Equations, when seen as the speed of electromagnetic waves, doesn't tell us what that speed is measured against. What it does tell us, if Maxwell's equations are valid (as Faraday's experiments suggest that they are) is that the speed will be measured as constant by any observer, in the same way that the values of ε0 and μ0 are measured as constant by any experimenter. And it's that fact, when its implications were considered very carefully, that led to Special Relativity.

barata
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Re: Absolute time and the speed of light

Post by barata » December 3rd, 2018, 10:32 pm

The trip was "instantaneous" because there was no trip. The "distance", therefore geographical points (which is really just a memory of one point, a mental impression of a certain experience, when compared with a present point), is itself merely a 'sense' of distance - and senses are also "wave vibrations". It is sensory perception that gives us relativity. Our brain processes constantly measures, using memories in order to contrast moments and events, for purely survival instinct reasons.

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Re: Absolute time and the speed of light

Post by Wmhoerr » January 15th, 2019, 6:47 pm

I would like to ask Happy recluse or anyone else if they know why light travels at 300km per second and not 200 km per second (say). Measurement does not equal understanding. I know Maxwell did some calculations from basics but i'm not sure whether added any clarity.

Steve3007
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Re: Absolute time and the speed of light

Post by Steve3007 » January 17th, 2019, 10:42 am

Wmhoerr wrote:I would like to ask Happy recluse or anyone else if they know why light travels at 300km per second and not 200 km per second (say). Measurement does not equal understanding. I know Maxwell did some calculations from basics but i'm not sure whether added any clarity.
On one level, we could simply say that this is similar to any other question as to why the universe is as it is, of why it exists in the first place. Perhaps the question has no meaning.

Alternatively we could look at the units in which the speed of light is quoted here and note that they are, of course, units that were invented by human beings as a result of the the scale of time and space of our immediate environment. Metres, kilometres and seconds were invented by humans because they fit human size and human timescales. In some other units, the speed of light would be different. In some units the speed of light is one. In some units Planck's constant is one. In some units the Universal Gravitational Constant is one. etc.

So perhaps the reason why, measured in the human units of metres and seconds, the speed of light is 300,000,000 ms-1 is to do with the physical size of human beings and the timescales over which we live, move and think. And those sizes and timescales are determined by the sizes and timescales of planetary systems that are suitable for the evolution of our kind of life. Perhaps it's only at space/time scales which make the speed of light have that number that intelligent life can evolve.

Perhaps it's like asking why my legs are exactly long enough to reach from my body to the ground.

Steve3007
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Re: Absolute time and the speed of light

Post by Steve3007 » January 17th, 2019, 10:46 am

Unlike physical constants with units, constants that have no units, such as pi, cannot be one. Although, I suppose, I'm only thinking of pi in base 10 arithmetic. In base pi arithmetic, pi is 10. Pi squared is 100. etc.

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Re: Absolute time and the speed of light

Post by Wmhoerr » January 18th, 2019, 9:23 am

Steve3007, you have avoided the question. You are saying that the problem will dissapear if the reference frame is changed. Not it won't. Why can't you just say that you dont know?

Steve3007
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Re: Absolute time and the speed of light

Post by Steve3007 » January 21st, 2019, 6:20 am

Wmhoerr wrote:Steve3007, you have avoided the question. You are saying that the problem will dissapear if the reference frame is changed. Not it won't. Why can't you just say that you dont know?
Why talk about my words as if I'm a politician who's avoiding a question because he has a political axe to grind? I'm just musing about the speed of light out of philosophical interest. But if you just want me to say "I don't know" I'm happy to oblige, if you think that would make for a more interesting conversation.
I would like to ask Happy recluse or anyone else if they know why light travels at 300km per second and not 200 km per second (say).
I don't know.

Fdesilva
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Re: Absolute time and the speed of light

Post by Fdesilva » January 22nd, 2019, 12:01 am

Wmhoerr wrote:
January 15th, 2019, 6:47 pm
I would like to ask Happy recluse or anyone else if they know why light travels at 300km per second and not 200 km per second (say). Measurement does not equal understanding. I know Maxwell did some calculations from basics but i'm not sure whether added any clarity.
I have wondered about this question too. There is one possibility that I have been doing a bit of investigation into. Here we go.
Historically the story goes, that Sir Isaac Newton, on observing the fall of an apple, formulated the theory of gravitational force. He then went on to show that the motion of planets was also due to the same force of gravity, that makes an apple fall. The thought that I wanted to investigate is the following. Suppose Newton made the observation that Hubble did, that is galaxies are moving away from each other due to an expanding universe, would he have then tried to investigate if all motion, that is even the falling of an apple, can be due to the expanding universe?

In other words the expansion of the universe is a fundamental property. The universe expands by creating New Time and New Space. Its like a 4 dimensional balloon that's growing bigger. We live on its edge. The edge of the universe is right here right now. The passage of time we feel is the expansion of time. Every moment we are stepping into new time, new space. Now the speed of light is constant because the (amount of space)/(amount of time) created in any given point is the maximum distance that an object at that point will be able to move. The movement is one with the expansion or one and the same as the expansion.
Here is a link to all that I have written about it http://tianweb.com/hubble.pdf

Steve3007
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Re: Absolute time and the speed of light

Post by Steve3007 » January 24th, 2019, 8:38 am

Suppose Newton made the observation that Hubble did, that is galaxies are moving away from each other due to an expanding universe, would he have then tried to investigate if all motion, that is even the falling of an apple, can be due to the expanding universe?
One apparent difference is that gravity appears to be genuinely universal. Every mass is gravitationally attracted to every other mass. But the expansion of the Universe only appears to be happening on a large scale.

Also, I don't see how this addresses Wmhoerr's question about the specific value of the speed of light (although, as he/she pointed out, I didn't have much success directly addressing that question either).

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Re: Absolute time and the speed of light

Post by Present awareness » January 24th, 2019, 7:30 pm

The speed of light is a measurement, based on a piece of wood 1 meter long. 1000 pieces of wood is 1 km. If you travel over 299,792,458 metres per second, you would be moving at the estimated speed of light.

One second, is also a measurement based on a circle, taking 60 of them to make a minute, or one revolution around the circle. All of these measurements are arbitrary, simply made up by humans to measure things. A meter could be any length of wood and there could be any number of seconds on a clock. Humans came up with an agreed amount of length and seconds in a minute. The point of all this is that light travels at whatever speed you would like to think it travels at, but there is a conventional agreed upon speed.
Even though you can see me, I might not be here.

Fdesilva
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Re: Absolute time and the speed of light

Post by Fdesilva » January 24th, 2019, 8:57 pm

Steve3007 wrote:
January 24th, 2019, 8:38 am
Suppose Newton made the observation that Hubble did, that is galaxies are moving away from each other due to an expanding universe, would he have then tried to investigate if all motion, that is even the falling of an apple, can be due to the expanding universe?
One apparent difference is that gravity appears to be genuinely universal. Every mass is gravitationally attracted to every other mass. But the expansion of the Universe only appears to be happening on a large scale.

Also, I don't see how this addresses Wmhoerr's question about the specific value of the speed of light (although, as he/she pointed out, I didn't have much success directly addressing that question either).
Here is the deal. The universe that is going to be in a say a billionth of a second from now. Does it exist now? What I am saying is that it does not exist now. It is what the universe expands into. The equation of motion of any particle/object in physics is of the form S= f(t) where S is the location of the object in space in relation to some reference frame. Over time S will trace a path. Now what I am saying is that the space that this path enters into is not space that pre existed but new space, just like the time that the object entered to is new time. This is a hypotheses.

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Re: Absolute time and the speed of light

Post by Present awareness » January 24th, 2019, 9:26 pm

Fdesilva wrote:
January 24th, 2019, 8:57 pm
Steve3007 wrote:
January 24th, 2019, 8:38 am


One apparent difference is that gravity appears to be genuinely universal. Every mass is gravitationally attracted to every other mass. But the expansion of the Universe only appears to be happening on a large scale.

Also, I don't see how this addresses Wmhoerr's question about the specific value of the speed of light (although, as he/she pointed out, I didn't have much success directly addressing that question either).
Here is the deal. The universe that is going to be in a say a billionth of a second from now. Does it exist now? What I am saying is that it does not exist now. It is what the universe expands into. The equation of motion of any particle/object in physics is of the form S= f(t) where S is the location of the object in space in relation to some reference frame. Over time S will trace a path. Now what I am saying is that the space that this path enters into is not space that pre existed but new space, just like the time that the object entered to is new time. This is a hypotheses.
I disagree with you and I’m saying that what is going to be, does exist right now. The light that just left the Sun will be here in roughly 8 minutes and 20 seconds. It is traveling through space as we speak and exist in the present moment, it just hasn’t arrived at our point in space yet, but it will.
Even though you can see me, I might not be here.

Fdesilva
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Re: Absolute time and the speed of light

Post by Fdesilva » January 25th, 2019, 1:35 am

Present awareness wrote:
January 24th, 2019, 9:26 pm
Fdesilva wrote:
January 24th, 2019, 8:57 pm


Here is the deal. The universe that is going to be in a say a billionth of a second from now. Does it exist now? What I am saying is that it does not exist now. It is what the universe expands into. The equation of motion of any particle/object in physics is of the form S= f(t) where S is the location of the object in space in relation to some reference frame. Over time S will trace a path. Now what I am saying is that the space that this path enters into is not space that pre existed but new space, just like the time that the object entered to is new time. This is a hypotheses.
I disagree with you and I’m saying that what is going to be, does exist right now. The light that just left the Sun will be here in roughly 8 minutes and 20 seconds. It is traveling through space as we speak and exist in the present moment, it just hasn’t arrived at our point in space yet, but it will.
In any event you are not in one point in space. Relative where you are right now it seems the same. But the earth is rotating whiles going around the sun. The sun goes around the centre of the milky way galaxy and the earth as a result also goes around. The milky way galaxy is moving apart from other galaxies due to the expansion. What do you say?

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Re: Absolute time and the speed of light

Post by Present awareness » January 25th, 2019, 1:53 am

If I’m walking down the street and look behind me, the space I was just in is still there and the space I’m walking towards is also there. Everything is here now, regardless of one’s particular location. Everything is in a state of constant motion from the galactic to the microscopic, even when I feel like I’m sitting still in my chair! However, no matter how far we go or where we move to, we never leave the present moment.
Even though you can see me, I might not be here.

Fdesilva
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Re: Absolute time and the speed of light

Post by Fdesilva » January 25th, 2019, 2:05 am

Present awareness wrote:
January 25th, 2019, 1:53 am
If I’m walking down the street and look behind me, the space I was just in is still there and the space I’m walking towards is also there. Everything is here now, regardless of one’s particular location. Everything is in a state of constant motion from the galactic to the microscopic, even when I feel like I’m sitting still in my chair! However, no matter how far we go or where we move to, we never leave the present moment.
What do you mean by we never leave the present moment?

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