Daily Archives: May 23, 2011

Gravity probe B experiment does not ‘prove Einstein right’

A good example of the problems of science journalism we discussed in the last post can be seen in this month’s media treatment of the important results from the NASA Satellite Gravity Probe B. After many years of frustration, the experiment has reported important evidence in support of two distinct predictions of the general theory of relativity – the geodesic effect (a distortion of spacetime by the earth) and frame dragging (caused by the rotation of the earth). See here for details of the experiment.

The result is a fantastic achievement. It offers important support for general relativity, a theory that underpins a great deal of modern physics, from our view of the origin of the universe to our understanding of black holes. It’s worth noting that such tests are rare and notoriously difficult (unlike the case of special relativity) and sincere congratulations are due to Principal Investigator Francis Everitt and all the team who worked so hard and so long to produce this important result.

The NASA Gravity Probe B Satellite

However, I was quite disappointed at the way the result was portrayed in newspapers and in science magazines. Almost without exception, the experiment was described as  ‘Einstein proven right‘ – see for example this article in the prestigious journal Science.

What’s the problem? The statement ‘Einstein proven right’ is deeply problematic for two reasons
1. As Einstein (and later Karl Popper) frequently pointed out, it is a basic tenet of the scientific method that no experiment can ‘prove’ a theory right. An experiment can offer supporting evidence but the case is never closed, because we do not know what new evidence may emerge in the future to cast doubt on other predictions of the theory
2. The constant personalization of the theory of relativity with Einstein creates the impression that the theory depends upon one scientist only, and devalues the work of hundreds of relativists since.
For the above two reasons, most physicists would have framed the result as ‘general relativity passes two important tests’.

It seems to me that such shorthand reportage does science no favours, as it misrepresents the result and plays into the hands of doubters and anti-science commentators. I wrote to Science to make this point; they have declined to publish my letter, so I am free to reproduce it here

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Re: At Long Last, Gravity Probe B Satellite Proves Einstein Right

News Section, Science, May 5

As a physicist and a science writer, I was surprised by your headline ‘At Long Last, Gravity Probe B Satellite Proves Einstein Right’ (News Section, Science, May 5).

To be sure, the Gravity Probe B experiment is a fantastic achievement that offers spectacular evidence in support of two distinct predictions of the general theory of relativity. This is important support for a theory that underpins a great deal of modern physics, from our view of the origin of the universe to our understanding of black holes. It’s also worth noting that such tests are rare and notoriously difficult (unlike the case of special relativity) and sincere congratulations are due to the team who worked so hard and so long to produce this important result.

However, your headline is problematic for anyone with a knowledge of the scientific method or an interest in the philosophy of science.

In the first instance, it is a fundamental tenet of science that no experiment can ‘prove a theory right’, as Einstein himself (and Karl Popper) frequently acknowledged. Even the most ingenious experiment can only offer evidence in support of a theory –‘right so far’ (and this is leaving aside the difficult question of the interpretation of scientific data). The error is not simply a question of headline shorthand as it is repeated in the opening sentence of the article;  ‘..a ..NASA spacecraft has confirmed general relativity’.

Second, it is a pity that relativity is so often portrayed as the work of one great scientist. Granted, it is a matter of historical record that the general theory of relativity was first formulated by Einstein singlehandedly. However, a great many mathematicians and theoretical physicists have explored, deepened and refined the theory since that time (obtaining solutions to the field equations and deriving concrete predictions from these solutions, for example). Framing the story in terms of Einstein alone ignores this work, and implies that the entire edifice of relativity is dependent upon one scientist.

In sum, it is no easy task to summarize a groundbreaking scientific experiment in a brief article, but most physicists would frame this important result as ‘general relativity passes another experimental test’ rather than ‘Einstein proven right’.

Yours sincerely

Dr Cormac O’Raifeartaigh

Visiting Fellow, Program on Science, Technology and Society, Harvard Kennedy School

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