Tuesday, July 1, 2014

Distant starlight, science, and magic

After the first episode aired back in March, I blogged about Telling a big story - Cosmos: A Spacetime Odyssey. The other dozen episodes of that television series also were memorable.

I was both amused and appalled to see some reactions from young earth creationists. After the second episode Danny Faulkner, who writes for Answers in Genesis, appeared on the March 20th Janet Mefferd show and whined:

“Janet :Now, do they do any interviews with scientists themselves during this whole thing, and do they ever give a creationist any time?

Danny: Well no, the creationists aren’t even on the radar screen for them. They wouldn’t even consider us plausible at all. I don’t recall having seen any interviews with people. That may yet come.”

In episode 4, A Sky Full of Ghosts, Neil deGrasse Tyson pointed out that since light has a finite speed it takes time to reach us, so we are seeing what was rather than what is. From the sun it takes eight minutes, from the planet Neptune it takes four hours, and from the nearest star (Proxima Centauri) it takes four years. Then he talked about the nebula that I’ve shown above and said:

“The Crab Nebula is about 6,500 light years from earth.

According to some beliefs, that’s the age of the whole universe, but if the universe were only 6,500 years old, how could we see the light from anything more distant than the Crab Nebula? We couldn’t. There wouldn’t have been enough time for light to get to earth from anywhere farther away than 6,500 light years in any direction.

That’s just enough time for light to travel through a tiny portion of our Milky Way galaxy. To believe in a universe as young as six or seven thousand years old is to extinguish the light from most of the galaxy, not to mention the light from all the 100 billion other galaxies in the observable universe.”

A review of that episode by Elizabeth Mitchell, M.D. at Answers in Genesis posted on April 1 (April Fool’s Day) objected:

“What Tyson, of course, does not address in the program is that young earth creation scientists do offer biblically consistent models to explain how we see faraway objects in space without attempting to tamper with the laws of physics. One such model is the anisotropic synchrony convention which is based on the fact—as Einstein recognized—that it is impossible to objectively measure the one-way speed of light. We instead must measure the round-trip speed of light and simply agree that the one-way speed must be half of the total. Read more about how this explanation would answer the question of how light from distant stars could reach earth within the time allowed in biblical history in ‘Distant Starlight’ and, for the more technically minded readers, ‘Anisotropic Synchrony Convention - A Solution to the Distant Starlight Problem.‘ “ 

I looked up the longer and funnier article on Distant Starlight (The Anisotropic Synchrony Convention) by Dr. Jason Lisle that was posted on December 8, 2010 rather than the brief one posted on February 24, 2010 that they now link to. He uses Einstein’s physics (relativity) as an excuse to sneak in a magical assumption:

“A less-well-known aspect of Einstein’s physics is that the speed of light in one direction cannot be objectively measured, and so it must be stipulated (agreed upon by convention). This stands in contrast to the round-trip speed of light, which is always constant.

For example, if light travels from A to B and then back to A, it will always take the same amount of time to make the trip (because its speed is always the same), and that time is objectively measurable. However, the time it takes to go just from A to B, or just from B to A is not objectively measurable. So the speed of light in one direction must be stipulated.”

Then he uses a silly example that would call for an absurdly long hallway (78% of the distance from the earth to the moon):

“We can calculate the round-trip speed of light. Let’s say, for example, we shine a light down a long hallway and it reflects off a mirror. If our stopwatch says it takes 2 seconds to go round trip, we can be sure of this time.

While we can be certain of the round-trip time, we cannot be certain of the time it took the light to travel to the mirror or the time it took to return.

We might assume that it takes light an equal amount of time to travel each direction.

However, the light could travel at different speeds for each direction.”

The simple solution where light has the same speed and takes the same time each way is shown above. That’s what you’d pick using Occam’s Razor.

But, that isn’t what Jason picks. As shown above, he makes a very peculiar assumption that the time in one direction is zero (and so the speed is infinite). It’s exactly what he needs to magically make that distant starlight problem vanish.

In the paragraph headed Distant Starlight he tries to explain:

“So we may choose to regard the speed of light as being instantaneous when travelling toward us, providing the round-trip speed (in empty space) is always 186,000 miles per second. In this case, the light from distant stars takes no time at all to reach the earth since the light is travelling toward us. So distant starlight is not an issue.

This convention could be called the ‘anisotropic synchrony convention,’ or ASC, because it claims that light travels at different speeds in different directions (anisotropic). Of course, it’s perfectly fair to use other conventions as well.

Einstein tells us that we may freely choose which convention to use. For the sake of simplicity, most physicists choose to regard light as moving at the same speed in all directions (isotropic). However, there is no fundamental reason that we cannot use ASC instead.”

In their discussion of this topic the Rational Wiki points out:

“One of the main problems with ASC, as a proof that there is no starlight problem in creationism, is that the use of a particular convention doesn't necessarily mean that the reality changes to match it.”

Then on June 18th at Answers in Genesis Danny Faulkner complained:

“More troubling was what appeared to be a direct response to biblical creationists that appeared in several episodes. For instance, in episode four, ‘A Sky Full of Ghosts,’ Tyson compared the idea that the universe is billions of years old to the possibility of the universe being only six or seven thousand years old. Why did the writers of that episode pick that particular age, if not to denigrate those who believe in biblical creation?”

Quit griping! You asked for it, and then you got it.

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