Is the speed of light a constant? Or can it vary? If so, in what kinds of situations, or how much?

Platte · Jul 25, 2024

Hans Blaster said:
Name one.

LHS 3154b
Discovered in 2023, this planet has a mass ratio that's more than 100 times greater than Earth's and the sun's. This discovery challenges current theories about how planets form around small stars.
ROXs 42 Bb
Discovered in 2013, this gas giant exoplanet is nearly 500 light-years away from Earth and is likely the largest known planet in the universe.

sjastro · Jul 25, 2024

Platte said:
I never said to adjust anything. I simply stated a fact which is we are unable to measure the one way speed of light. My point wasn’t to use light in support of Creation - but to point out that since we don’t know than it shouldn’t be used to debunk it. It seemed to me that most people didn’t realize that and I havnt really seen it be mentioned (that the One way speed of light can’t be measured). I’m not an advocate for YEC. God creating the world young wouldn’t make much sense if He wanted the Earth to be hospitable and functional for Adam from the beginning.

Hasn't it been made perfectly clear to you the one way speed of light has been debunked because it is not science.
Do you understand the speed of light is 299,792,458 m/s and the modern definition of a metre as has been explained to you is the distance travelled by light in one second namely 1/299,792,458.
If the speed the light v was infinitely large in one direction it would mean the length of a metre would be zero.

Do you think it makes any sense for a metre to be a zero length in one direction and non zero in the opposite direction?

Platte said:
Have no idea who that is.

A Jason Lisle video was presented earlier in this thread who is a physicist and YECist and advocates the speed of light in one direction is infinite.

sjastro · Jul 25, 2024

Platte said:
Yes it was discussed there. The light topic was moved here so more science minded people could confirm what I said - that the one way speed of light cannot be measured.

You didn’t find that interesting? I find little things like that very interesting

Platte wrote,
also It is interesting that we can’t see any planets further than 6000 light years away. Planets are seen with reflective light which we do know is 186,000 miles per second.

The science minded people have not confirmed what you said as you seem to be under the impression the one way speed of light is a relevant topic in science.

Let me emphasise again it is not science, its blind acceptance would mean we would have to throw out legitimate science on the age of the universe which is based on two methods.

(1) The use of temperature variations in the cosmic radiation background which gives information on density, composition and expansion rate of the early universe as well providing cosmological parameters from which the age of the universe can be calculated.
(2) Using redshift measurements from galaxies and their distances determined from variable light sources such as Cepheid variables and type 1a supernovae supernovae.

The relevant issue is that both methods produce age ranges that do not overlap which may be due to problems with the data or perhaps requires new physics to resolve.

Hans Blaster · Jul 25, 2024

Platte said:
LHS 3154b
Discovered in 2023, this planet has a mass ratio that's more than 100 times greater than Earth's and the sun's. This discovery challenges current theories about how planets form around small stars.

13 x the Earth mass = 0.00004 Sun mass. No star is that small

Platte said:
ROXs 42 Bb
Discovered in 2013, this gas giant exoplanet is nearly 500 light-years away from Earth and is likely the largest known planet in the universe.

4 x the mass of Jupiter = 0.004 Solar masses. No star is that small either.

Carl Emerson · Jul 25, 2024

essentialsaltes said:
That's entirely separate from the one-way versus two-way speed of light.

I agree - science does not support such a theory, but science does support time changing its rate.

Platte · Jul 26, 2024

sjastro said:
Hasn't it been made perfectly clear to you the one way speed of light has been debunked because it is not science.
Do you understand the speed of light is 299,792,458 m/s and the modern definition of a metre as has been explained to you is the distance travelled by light in one second namely 1/299,792,458.
If the speed the light v was infinitely large in one direction it would mean the length of a metre would be zero.

View attachment 352201

Do you think it makes any sense for a metre to be a zero length in one direction and non zero in the opposite direction?

A Jason Lisle video was presented earlier in this thread who is a physicist and YECist and advocates the speed of light in one direction is infinite.

No problem. If the one way speed of light (direct light) has been measure then point me to that. I am not advocating for it to be unequal to 2 way light. I’m simply pointing out that we don’t know and that it could be significantly different or it could be the same

Platte · Jul 26, 2024

sjastro said:
The science minded people have not confirmed what you said as you seem to be under the impression the one way speed of light is a relevant topic in science.

Let me emphasise again it is not science, its blind acceptance would mean we would have to throw out legitimate science on the age of the universe which is based on two methods.

(1) The use of temperature variations in the cosmic radiation background which gives information on density, composition and expansion rate of the early universe as well providing cosmological parameters from which the age of the universe can be calculated.
(2) Using redshift measurements from galaxies and their distances determined from variable light sources such as Cepheid variables and type 1a supernovae supernovae.

The relevant issue is that both methods produce age ranges that do not overlap which may be due to problems with the data or perhaps requires new physics to resolve.

I havnt made any claim of relavance to anyone. I simply said science will confirm that we have not and cannot test the one way speed of light.

Do you agree from a science Standpoint that we have not and cannot measure the one way speed of light. That we (Einstein) make the assumption that it is the same as 2 way?

Platte · Jul 26, 2024

Hans Blaster said:
13 x the Earth mass = 0.00004 Sun mass. No star is that small

4 x the mass of Jupiter = 0.004 Solar masses. No star is that small either.

The smallest known star is named EBLM J0555-57Ab and it's the smallest star ever measured, at just a sliver larger than Saturn.

https://www.skyatnightmagazine.com/news/smallest-known-star-discovered

Tinker Grey · Jul 26, 2024

Platte said:
The smallest known star is named EBLM J0555-57Ab and it's the smallest star ever measured, at just a sliver larger than Saturn.

https://www.skyatnightmagazine.com/news/smallest-known-star-discovered

Mass and dimensions are not the same thing.

Platte · Jul 26, 2024

Tinker Grey said:
Mass and dimensions are not the same thing.

Agree. Dimensions are what I’m looking at

BNR32FAN · Jul 26, 2024

Neogaia777 said:
Ok, so I watched the video.

But time itself is different depending where you are at in the universe, etc. Depending upon where you are in the universe, that time is always "now", etc, and the universe is the same age equally everywhere, despite whatever images there is that you are seeing of them from where you are currently at in it currently, etc.

He brought up that what if the images we are seeing from where we are in the universe, what if those are not older, etc? And so I'm wondering if you could disprove that theory/hypothesis by proving that they are maybe, etc?

By proving that the images/radio signals themselves are older, but that the place itself is not actually, etc. Wouldn't that disprove the hypothesis that the one way speed of light could be different maybe, etc? Or would it not really, etc?

What do you think?

Take Care/God Bless.

Why would time be different in different parts of the universe?

BNR32FAN · Jul 26, 2024

sjastro said:
The example I gave shows the anisotropic speed of light is a mathematical issue which doesn't reflect reality.

As has been stated earlier in this thread it is impossible to measure the one way speed of light so it is pointless for young earth creationists to speculate on velocities.
A point to consider is Occam's razor, where the simplest explanation is usually the best where the speed is c in all directions.

Well when you’re dealing with young earth creationists you’re dealing with people who believe that the creation process was a miracle and therefore not expected to coincide with the natural laws of science. After all why should creation be expected to coincide with science any more than the virgin birth, the resurrection, or any other miracles recorded in the Bible?

BNR32FAN · Jul 26, 2024

sjastro said:
You are not going to travel at the speed of light because you have non zero mass.
The issue will always be an inability to synchronize clocks at the source and destination, the clock at the destination must know exactly when light is emitted from the source as measured by the clock at the source.
To do this a signal at the source travelling at an infinite speed must be emitted at the same time as the light and instantaneously reach the clock at the destination after which both clocks are synchronized.

The clocks could be synchronized if both clocks were synchronized here on earth and someone brought one of them to the destination.

Hans Blaster · Jul 26, 2024

Platte said:
The smallest known star is named EBLM J0555-57Ab and it's the smallest star ever measured, at just a sliver larger than Saturn.

https://www.skyatnightmagazine.com/news/smallest-known-star-discovered

Who measures stars by radius for "smallest"?

Platte · Jul 26, 2024

Hans Blaster said:
Who measures stars by radius for "smallest"?

Radius is how we measure the size of a circular object. Size is the amount space an object occupies.

Hans Blaster · Jul 26, 2024

Platte said:
Radius is how we measure the size of a circular object. Size is the amount space an object occupies.

Mass is how astronomers discuss "small" and "large" stars, not radius.

But this is all a distraction from your claims about reflected light being "special".

Platte · Jul 26, 2024

Hans Blaster said:
Mass is how astronomers discuss "small" and "large" stars, not radius.

But this is all a distraction from your claims about reflected light being "special".

No - the context of our conversation was seeing planets and seeing stars in space from earth....generally speaking larger planets would be easier to see from earth from great distances then smaller planets.

The only thing I've claimed that is "special" about reflected light is that 2 way light (reflected) has been measured - 1 way light (direct) has not been measured. Do you dispute that?

sjastro · Jul 26, 2024

Platte said:
No problem. If the one way speed of light (direct light) has been measure then point me to that. I am not advocating for it to be unequal to 2 way light. I’m simply pointing out that we don’t know and that it could be significantly different or it could be the same

Platte said,

I havnt made any claim of relavance to anyone. I simply said science will confirm that we have not and cannot test the one way speed of light.

Do you agree from a science Standpoint that we have not and cannot measure the one way speed of light. That we (Einstein) make the assumption that it is the same as 2 way?

This is getting very repetitious.

(1) Special relativity postulates the speed of light is isotropic (the speed is the same to all observers) where the two way speed of light is the same as one way speed of light and equals 299,792,458 m/s.

(2) If the speed of light was anisotropic (the speed is not the same to all observers) is a violation of special relativity as a special frame of reference must exist. Physicists searched for this special frame in the form of an ether frame which was once believed necessary to explain the propagation of light in space.
Interferometer testing indicated a null result, there was no special frame and the speed of light is therefore isotropic where Einstein’s assumption that the two way and one way speeds of light are equivalent is the simplest and most logical explanation.

(3) Special relativity is supported by experiments and observations, the main rival theories of stationary ether and stationary ether with Lorentz contraction are examples where the speed of light is isotropic to the ether itself but anisotropic to a moving observer relative to the ether.

As the table shows the ether theories are either contradicted by or not applicable to various observations and experiments adding further weight to Einstein’s assumption.

(4) Having to repeat myself again science is based on evidence, not about debating philosophical and metaphysical concepts like the speed of light being anisotropic which is unfalsifiable and therefore science does not have a standpoint.

sjastro · Jul 26, 2024

BNR32FAN said:
Well when you’re dealing with young earth creationists you’re dealing with people who believe that the creation process was a miracle and therefore not expected to coincide with the natural laws of science. After all why should creation be expected to coincide with science any more than the virgin birth, the resurrection, or any other miracles recorded in the Bible?

Perhaps this applies to your run of the mill YEC, but there is also the pseudoscience Creation science - Wikipedia which attempts to conflate science with YEC.

sjastro · Jul 26, 2024

BNR32FAN said:
The clocks could be synchronized if both clocks were synchronized here on earth and someone brought one of them to the destination.

It doesn't work as the process of moving the clock to the destination introduces time dilation and the clocks are no longer synchronized.
Getting around this problem by moving the clock slowly to the destination results in another problem in the case for anisotropic light, the clocks can no longer detect time differences between light moving in opposite directions.

If the speed of light is anisotropic the time dilation τ equation is:

ϒ is the Lorentz factor, κ is the anisotropic factor which varies from -1 to +1 and v is velocity of moving the clock.
If the velocity is very small;

This is the inverse Lorentz factor which crops up in special relativity and only applies to two way light or light which is isotropic.

Is the speed of light a constant? Or can it vary? If so, in what kinds of situations, or how much?

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