The anisotropic synchrony convention is a potential solution of the starlight problem put forward by Dr Jason Lisle. It proposes that the speed of light isn't quite the constant that everyone thinks it is, but that it travels at different speeds in different directions. This idea was published in Answers Research Journal in September 2010.
 The "one way" speed of light
To better understand what Lisle is blabbering on about, consider a thought experiment about measuring the speed of light. If you wanted to measure the speed of light in one beam going from A to B you'd need two clocks that are perfectly synchronized. This is, however, impossible because of issues with even defining time in the context of relativity. Naively, you would say that you would synchronize your clocks at point A, then walk one clock over to point B. You stop clock A when you fire off the photon and stop clock B when the photon hits. You carry clock B back to clock A and compare the two times (or send a message some other way), which gives you the one-way velocity of light. However, relativity rears its ugly head here. The process of moving one clock to point B necessarily means that the two clocks will run at different rates once they are separated and thus no longer be synchronized when the photon is fired. In an isotropic framework you would say they drifted apart because they had relative velocity; in an anisotropic framework you would say that they drifted apart because they were separated by distance (regardless of how fast they moved apart). Any attempt to resynchronize the clocks by calculating how much they should have drifted apart over the trip will require you to, in essence, pick how you think light behaves: if you think it travels at equal speed in all directions, you adjust your moved clock one way; if you think light does not travel at equal speed in all directions you make a different calculation and get a different result. The experiment itself cannot tell you which choice is correct. Thus, this "one way" speed of light from A to B is undefined. We can, however, successfully measure a "two way" speed of light where it travels from A to B before being reflected back to A; this requires only one clock and the problem of synchronizing two definitions of time disappears. Simply measure the time it takes for light to bounce back, double the distance, and you arise at at a reliable value for the average speed of light over the closed loop independent of clock synchronization.
 The general premise
- It is, even in principle, impossible to measure the one-way speed of light. Because of the effects of relativity, clocks cannot be moved apart without changing the rate at which they run, and therefore you can't just shoot a beam of light from one clock to another and record the start and stop times.
- Basically, all any conceivable experiment can do is provide you with the round-trip speed of light between two points. If you think that an experiment measures the one-way speed of light, it is because you are making assumptions about what 'synchronized clocks' mean.
- When Einstein formulated his theories of relativity, he chose to assume that light travels the same speed in all directions (the 'isotropic convention'); that is, the speed of light is exactly the same on the outbound leg as on the return trip. Moreover, Einstein did this quite explicitly, having considered other alternatives. The isotropic convention has a number of advantages, not the least of which is that it makes some kind of intuitive sense and it makes a lot of the math much easier.
- It is, however, possible (as in, 'the math can be made to work') to state that for any observer, light traveling toward the observer travels at greater than c, and light traveling away from the observer moves slower than c,, such that the average speed over the whole round trip is exactly c. For Lisle's purposes, light traveling toward the observer travels at infinite speed, while light travels at 1/2 c in the opposite direction. Yes, it may seem counterintuitive, but all of relativity, electromagnetics, etc., can be redrafted within this 'anisotropic synchrony convention', or ASC, just like physics can be done with the metric system or Imperial units (or both, with hilarious consequences, like smashing landers into Mars).
- The weirdnesses that we have come to accept in the Einstein isotropic convention (clocks slowing down or speeding up depending on how fast you are moving relative to another observer, for example) are exchanged for a different set of weirdnesses that we have not become accustomed to due to long exposure (like clocks running faster or slower depending on how far apart you are, not how fast you are moving). Thus things like the orbital periods of Jupiter's moons appear to change, not because of the lightspeed delay from Jupiter to Earth changing as the distance between them changes, but because time itself runs differently depending on the differing distance from Earth to Jupiter given their relative orbital positions.
- Picking the anisotropic synchrony convention or Einstein's isotropic convention is arbitrary, like picking base 10 or base 12 for doing mathematics. One is not more 'real' than the other, although they individually make different aspects of relativistic mathematics easier. Does light take billions of years or zero time to cross the universe? I don't know: does water freeze at 0° C, 32° F, or 273.15 K?
- Based on Lisle's interpretation of the Bible, he feels that it was written using the anisotropic synchrony convention rather than Einstein's isotropic convention. Imagine that the Bible said that God made 10 living goats, and gave a third of them to each of three people. You'd see a problem with such a statement, what with the thirds of goats and all, but what if the Bible were written in base 12? Then everyone could get four whole goats, no problem. God made all the stars in one day, and their light reached Earth the same day? With Einstein's isotropic convention, that's a problem, but with the ASC, it isn't.
Lisle's real argument, the one that the math has just been softening you up for, is this: to show that the Bible even has a 'starlight problem', you must first prove that the Bible was NOT written using an anisotropic synchrony convention. If you can't prove that (and it's hard to see how you would go about doing so, since it's not in the Materials and Methods section), then you can't prove that the Bible is wrong about distant starlight hitting the Earth on the same day the stars were created. QED.
 The anisotropic solution
The above issue isn't really a problem for physics, nor is it original to Lisle. There is currently no consensus that the one-way speed of light is a convention, but the conventionalists are acknowledged to be ahead in the fourth quarter. Relativity, and the Maxwell equations that underpin it, have been recast into forms consistent with other synchrony conventions, should anyone desire to make use of them. Almost no one does, as the new forms are horribly and unnecessarily complicated—if the one-way speed of light is a convention, it's much easier to choose the simplest (always equal to c), though it may turn out that some classes of problems might be more easily solved with a different convention.
Lisle has appropriated the conventionalist position to argue that when coming towards the Earth light can be assumed to have an infinite speed—but when traveling the other way it can be assumed to move at only half the accepted speed of light—which is also not original to him. This would allow distant starlight to reach Earth by Creation Week but still allow experiments to show the speed of light as c, and still be consistent with relativity. His argument is that Genesis is written from the point of view of this synchrony convention.
It's important to emphasize that synchrony conventions are mainstream, though obscure, physics; the problem has been discussed for over 70 years, and arguably (by Poincare) before relativity was invented. Jason Lisle's purpose for using it is twofold: one, it gives creationists aid and comfort; two, it sucks anti-creationists into an irrelevant discussion where they can be shown not to be as well-informed as Jason Lisle is. Rarely have creationists risen to this level of magnificent bastardy.
 Observational evidence
One of the main problems with ASC, as a proof that there is no starlight problem in creationism, is that a convention doesn't necessarily mean that the reality changes to match it. It's much like choosing a co-ordinate system for a making a map; in principle we can develop a co-ordinate system where the Earth is fixed and stationary at the center of the universe - indeed, most maps and navigation on the planet implicitly assume this. This doesn't, however, mean that the Earth is at the center of the universe and stationary. There is a similar proposition in spin physics where the calculations move from a stationary to a rotational frame of reference; this doesn't mean that the room itself starts spinning at 400 million times per second, just that the co-ordinate system does. In short, changing co-ordinates and conventions are just that - it's the map co-ordinates that change. Lisle's assertion of an anisotropic convention doesn't necessarily mean that there really is a one-directional speed of light that is infinite, or near infinite. If anything, anisotropy is more of a thought experiment and only really works in one dimension, where the different speed of light, the anisotropy, changes only in a linear direction.
When the anisotropy varies only in one direction, the convention holds and perhaps Lisle's assertion that the speed of light really could be infinite in one direction might be true - it probably isn't but it might be. However, when it varies radially about the Earth, which is exactly what needs to happen to solve the starlight problem and exactly what Lisle implies, there would have to exist a geocentric gravitational field independent of any mass. A detailed explanation has been written by Timothy V Reeves, referencing work on Edwards space-time done by Jian Qi Shenk, showing how the direction of anisotropy must be constant, or an extra gravitational field is generated.
 See also
- ↑ Lisle, Jason. "Anisotropic Synchrony Convention—A Solution to the Distant Starlight Problem." Answers Research Journal 3 (2010): 191-207.
- ↑ See the Wikipedia article on One-way speed of light.
- ↑ after nearly two years of promises from Lisle to radically change our understanding of light
- ↑ The Sensuous Curmudgeon - Jason Lisle’s “Instant Starlight” Paper
- ↑ Quantum Non-Linearity - Answers in Genesis Screws It up Again