The Lightness of Fine-Tuning - Part 1

I’ve recently noticed efforts to tie a number of physical constants, including the speed of light, to the Fine-Tuning Argument.  From my perspective this is a disturbing, but still quite exciting development because many years ago I looked very closely at the speed of light and I saw absolutely nothing to suggest that the speed of light, or any of the other physical constants were fine-tuned (not then, not now). Finally, I get an opportunity to put that effort into use!

I don’t really want to bamboozle the casual reader, so I’ll be doing something a little unusual.

In this article (and the one that follows) I’ve tried to simplify the issues involved without misrepresenting the facts. I have also posted a more serious, methodical variation on the central argument, namely that Einstein’s Special Relativity equations can be derived from Newtonian (or Galilean) Relativity. I suggest reading the first two parts of this series and then, if your appetite is whetted, you can sink your teeth into something a little more complex.

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Josh Willms, in the Honest Search For Truth blog, said:

Keep in mind that we are considering the possibility of an outside intelligence making fundamental changes to the universe. We should not rule out this possibility from the get-go. An outside intelligence could alter the speed of light while holding distance and time constant, stretch space while holding the speed of light and time constant, or change the rate of passage of time while holding the speed of light and distance constant.

He concludes:

In short: The ratio of the speed of light to distance and time could be different. It is possible for the speed of light to be fine-tuned.

I must point out that Josh admits that his training is in biology, that he's not a physicist and that he might be wrong.  True to the name of his blog, he is searching for Truth wherever it lies, not confirmation of the first idea that he stumbles across!

For the lay reader, it's easy to get tripped up by relativity. I recall meeting with a Professor to discuss some of the finer points of Special Relativity and he admitted that even he found them a bit confusing at times. (And while it wasn't strictly his area of expertise, he did have to teach it as part of the university curriculum!)

As seems to be increasingly the case with proponents of Intelligent Design (for example, the Discovery Institute), science is being bent (and warped) to support arguments for a supernatural creator.  These ID theorists either deliberately misrepresent the facts (relying on the fact that their audience doesn't know enough about the subject to see the errors) or, and this is more likely, their desire to find evidence (and their faith) overwhelms their critical faculties.

As long as before the new millennium, I began to worry that ID theorists would move into other fields of science, that they would not be content with corrupting evolutionary biology or palaeontology.  Sadly, these concerns seem vindicated.

Anyway ... back to Josh’s comments.  Josh is not an ID theorist, but he’s discussing something that is core to those who are – “fine-tuning” as it pertains to cosmology and physics.  I left a response to the blog article from which I took the comments above, noting that the speed of light, c, is related to the granularity of the universe, a response that I’d like to expand on a little in this and a couple of future posts.

The universe is not infinitely divisible, neither in terms of space nor in terms of time or, in other words, there comes a point at which you will reach the smallest divisions of space and time.  “This small and no smaller.”

The smallest meaningful division of space is the Planck length and the smallest meaningful division of time is the Planck time.  (See also Why I Like Planck, written a long time later than this post.)

It might be possible to overstress the importance of Planck units but it would take some real effort to do so. Unlike the metre and the second, Planck length and Planck time are not arbitrarily defined by humans; they represent a reality of space and time at the deepest, most fundamental level.  For this reason, they are also referred to as “natural units”.

It is no co-incidence that the value of c is one Planck length per Planck time. 

It should be noted that the common name applied to c is historical – it is not merely the speed at which light happens to travel; it is the fastest speed at which anything can travel.

That is to say: light travels as fast as it possibly can and c happens to be the fastest anything can travel.

Now imagine a Law Abiding, Speedy Rider (“laser”) cruising along a freeway which has a speed limit of c.  We might notice that the speed of a “laser” is c. The value of c isn’t related to the speed of the “laser” per se, if the speed limit were 2.5c, then the “laser” would travel at that.

Similarly the speed of light isn’t related to light per se. If the universe permitted a higher speed, light would travel at it.  Of course that higher speed would then be “the speed of light”, but it would not be what we today call c.

But, and this is an important "but":

a higher speed in terms of natural units is simply not possible

Even if we changed the dimensions associated with the granularity of the universe, the speed of light would still be equal to the fastest speed possible in that newly recalibrated universe and that fastest speed possible would be equal to (the smallest division of space) / (the smallest division of time).

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In Part 2, I discuss an interesting thing you can do with relativity which might (or might not) throw some light on this issue.

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Note: The Professor I mentioned was struggling with the same issue that I was struggling with at the time, namely that the "priming notation" associated with Special Relativity is used inconsistently.  The majority of physicists working in the area will swear on all nine lives of their most beloved cat that the priming notation isn’t used inconsistently. Addressing this was the central thrust of the more methodical argument, but I've trimmed it back for the purposes of posting on this blog (which I did just before posting Part 2).