Fiddling with “fine-tuning”

In The ghetto of apologetics “science” I described the role that apologetics and creationist/ID groups, institutes and web sites play in distorting scientific findings to support their particular ideological and religious beliefs. Here I give an example of how these groups distort the “fine-tuning” argument because of their pre-conceived beliefs – their confirmation bias.

The cosmological constant, often equated with dark energy, influences the expansion of the universe so it’s value is important to us. The fact that this expansion has enabled the formation of stars and therefore life (as evidence by our existence) provides a limit on the values it can take. This from In his book Origins: Fourteen Billion Years of Cosmic Evolution Neil de Grasse Tyson, an astrophysicist and Director of New York’s Hayden Planetarium, concludes “our existence limits the cosmological constant to a value between zero and a few times its actual value, while ruling out of play the infinite range of higher values.” Not too high, but a reasonable range.

The apologetics distortion

But this is how the Christian apologists spin the cosmological constant.

William Lane Craig from the apologetics website Reasonable Faith says (Probability of Fine-Tuning):

“For some of the constants, like the cosmological constant, the range of life permitting values is incomprehensibly tiny in comparison with the range of values we see that it could have, so that the chances of the constant’s having the value it does is virtually next to impossible.”

Also Craig says (On the Argument for Design from Fine-Tuning):

like the so-called cosmological constant, which must be fine-tuned to one part in 10 120 in order for life to exist, are being discovered as physics advances.”

Rich Deem at the Evidence for god web site says similarly (fine tuning and the cosmological constant):

“How finely tuned must this energy density be to get a flat universe? One part in 10120″

Hugh Ross, from the Reasons to Believe says: Ross 2002:

“To achieve the precise rate and timing of the cosmic slowing down and speeding up, two characteristics of the universe must be fixed with exacting precision. The mass density cannot vary by more than one part in 1060 and the space energy density cannot vary by more than one part in 10120 (that’s 120 zeroes behind the 1) (Krauss 1998).”


Of these, the most sensitive is the space energy density (the self-stretching property of the universe). Its value cannot vary by more than one part in 10120 and still allow for the kinds of stars and planets physical life requires”.

In a few words the apologists Craig, Deem and Ross (who are considered sacred authorities by their followers) claim the cosmological constant (space energy density) cannot vary by more than 1 part in 10120 – Very different to Tyson’s conclusions, isn’t it?

So why did they get this so wrong? And why do they all quote a fine tuning of 10120?

Where does 10120 come from?

Ross gives a reference to Krauss (The End of the Age Problem, and the Case for a Cosmological Constant Revisited) as his source of information. But he has distorted it. Krauss actually said:

“The problem with this from a fundamental perspective is that a cosmological constant associated in modern parlance with a nonzero vacuum energy density in the universe on a scale that would be cosmologically relevant and yet still allowed today would take a value that is over 120 orders of magnitude smaller than the naive value that one might expect based on considerations of quantum mechanics and gravity.”

In other  words the disagreement between the naive theoretical value and the measured value is a factor of 10120.

So we have gone from scientists reporting a huge theoretical overestimation of the value of the cosmological constant (by 10120) to apologists claiming that the cosmological constant cannot be varied by more than 1 part in 10120!

Now there could be a fine tuning aspect to the value of the cosmological constant – just not the one claim by Craig, Deem and Ross. The huge discrepancy between the naïve theoretical value and the measured value could possibly be explained by the theoretical value due to quantum mechanics and gravity being balanced by some other (unknown) input. But the chances for this to happen so exactly (that is for the unknown factor to balance so the theoretical value so exactly) would be extremely remote. Krauss points out this was a reason why many particle physicists preferred a mechanism “that would drive the cosmological constant to be exactly zero today.”

Eli Michael made a similar comment in 1999 (How physically plausible is the cosmological constant?):

“This argument, however, leads to the belief that the cosmological constant is exactly zero, for how could the fields conspire to cancel out all but 1 part in 10120″

And characteristically Deem quotes Michael as his reference for the distorted presentation quoted above.

However, there are other possibilities. These include the possibility that dark energy is not the same as, or more than, the cosmological constant. Possibly some of the components are strongly related but of opposite sign so cancel out or maybe our understanding of how gravity responds to the energy density is flawed. The very recent discovery of dark energy is surely an indication that we still have a lot to learn in this area.

The apologetics motivation

The important point is that the Christian apologists were attracted to the large number – the 10120 difference between the theoretical and measured values. They weren’t at all interested in the details – just that here was another large number they could (mis)quote. They eagerly grabbed at this and reinterpreted it to satisfy their “fine-tuning” preconceptions.

So now the cosmological constant has been repackaged and sold on to their followers providing them with another “proof” for their designer god.

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3 responses to “Fiddling with “fine-tuning”

  1. Ken —

    A may not be smart enough to understand this argument (ot: there is a very funny bit John Safran has that understanding string theory is necessary before one can assert they are an atheist).

    My question and I hope you can clarify:

    you quote Craig as writing “so that the chances of the constant’s having the value it does is virtually next to impossible.”

    If I understand you correctly you are saying scientists assert the real range of possible options is much smaller – why do you assert this? I refer to the full range of possible settings not merely those that would enable star formation.



  2. The “real range of possible option” is, in a sense, a different issue. After all, for many physical constants it could be that only one value is possible so it is pointless to talk about how “fine-tuned” they are (as this implies a value arising by chance from a whole range of values). At this stage we just don’t know one way or the other for many constants.

    In the case of the cosmological constant we can speculate that it must lie within a certain range (“zero and a few times its actual value”) because of the consequences on the expansion rate and how this would effect formation of galaxies, stars, etc. (of course we just don’t know what the “possible range is – it could be much smaller than than that – maybe a single value – it could be much larger). My point is that this “possible” range is much bigger than 1 part in 10^120 commonly claimed by apologists. It does not provide support for the “fine-tuning” claims – at least in the way they present it.


  3. Pingback: Going beyond the evidence | Open Parachute

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