# What if the speed of light was not constant? [closed]

How would the laws of physics change if the speed of light was not constant and the Michaelson-Morley experiment was instead proven to be true?

Obviously relativity would not be true, but on a small scale, what would the differences be? Would Maxwell's equations hold up properly? Would electricity work as it does now? How would light work (if at all)?

Answers should assume that all discoveries before the Michaelson-Morley experiment still hold (or give reasons why they should not; or why they appeared to hold in the past but a non-constant $c$ shows that they will not hold in all situations)

## Assumptions

If needed:

• No maximum speed of light
• Instantaneous transmission of information is possible, but would have to be via gravity or similar.
• Most things that emit light do so at a constant rate which is comparable to $c$
• Newtonian mechanics work properly for ordinary objects (e.g. planets, thrown balls, etc.)
• Luminous Aether is real: https://en.wikipedia.org/wiki/Luminiferous_aether

## closed as too broad by AndreiROM, James♦, Hohmannfan, DaaaahWhoosh, TrEs-2bJun 9 '16 at 16:04

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• I'd like a [hard-science] answer but since this question may involve reworking a century of electromagnetism I removed [hard-science] and went with [science-based]. – Nathanael Farley Jun 9 '16 at 11:27
• You can clarify in the question body that you want answers to conform to the relevant sciences are they were known before the work of Einstein et al. Comments are potentially subject to deletion at any time for any reason, and should not be relied upon to remain. – a CVn Jun 9 '16 at 11:30
• This feels like it could easily be horribly broad. You might need to narrow down the scope of what you're asking about. – Tim B Jun 9 '16 at 12:21
• I agree, this question is far too broad. The implications are universe changing on many different levels. – AndreiROM Jun 9 '16 at 13:16
• OK, I'll reduce the scope of the question to just the Maxwell equations and thier direct implications tonight (probably changing to [hard-science] tag) . Feel free to mark this as on hold until I can change it. – Nathanael Farley Jun 9 '16 at 13:22

One part of the Michaelson-Morley experiment is not that light travels at variable speed, but that it travels through the luminiferous aether at a fixed speed and that the Earth was moving through the aether and that the aether might have some movement of its own.

If you assume that this is where the differences start, and that light travels at a given speed through the aether, which is stationary relative to the galaxy, then the main problem comes in the changing speed of light in varying directions (if the aether is not stationary relative to the galaxy, then that would farther complicate things and I won't talk about this).

The sun is currently orbiting around the center of the galaxy at a speed of about 220 km/s, and the earth is orbiting the sun at a speed of about 30 km/s. This would cause the speed of light to potentially vary by up to 500 km/s as measured by scientists on Earth. This may seem like a huge number, but the speed of light is almost 300,000 km/s, so the difference is not that big.

500 km/s change is actually less than the error that scientists had had when calculating the speed of light for almost 200 years after it was discovered that light had a finite speed.

Furthermore, relativity could no longer be the case. It requires that light always travel at a constant speed, so this would cause superluminal travel to no longer be that big of a deal. It simply becomes a matter of accelerating yourself enough, and you don't have to worry about your inertial mass increasing, or time dilation, or length contraction.

Also, red-shift and blue-shift are now caused by an object's movement through the luminiferous aether. This would wreak havoc on astronomy as many astronomical observations depend upon it (such as the universe expanding). Christian Doppler relied on light not traveling through a moving medium in his original discovery of the Doppler Effect in 1842 (before the Michaelson-Morley experiment).

The lack of relativity would actually simplify making a GPS system because modern GPS systems have to adjust for relativistic time dilation.

This lack of space-time curvature also would make the inner solar system more stable because space-time curvature caused by relativity and the sun's mass could make Mercury's orbit unstable and cause it to get more eccentric, eventually being flung out of the solar system, colliding with another planet, or falling into the sun in the next few billions of years.

There are probably much more implications, but I don't think there is a way around the two assumptions that I made (light moves at always the same speed relative to the aether, as thought be the luminiferous aether theory and that the aether's wind is very little relative to the movement of our galaxy) without overly complicating things or destroying the entire universe.