The Half-Astrophysicist Blog

Do Conservatives Believe in GPS?

I don’t get too political here…it’s mostly astronomy and science.  Sometimes, however, crazy politics turns up in the place you least expect.

There is a website called Conservapedia (I am not linking to them because, well, I don’t have to).  It is the Conservative version of the universe without always a sound grasp of reality.  Now I expect them to rag on the traditional hot button topics such as stem cell research, evolution and global warming.

Today it came to my attention that they have also included Einstein’s Theory of relativity as an example of liberal science!  To which I can only say, WTF?  I have read all 24 of the “counterexamples” which Conservapedia claim disprove relativity.  Whoever wrote this list obviously have never taken a single course in relativity or astronomy.  Don’t let the “footnotes” fool you.  I have followed a couple of them to the cited papers and the papers don’t support what they say at all (such as their objection to the Pulsar PSRB1913+16.  I read the paper and the graph clearly shows NO divergence from general relativity outside the experimental uncertainties).

Many of their “arguments” are philosophical assertions that have no basis in science.  Anyone with an undergraduate degree in physics should be able to explain how a photon has momentum but not mass, something that is beyond the comprehension of Conservapedia (leading me to believe they have less than an undergraduate education in physics).   We have been measuring anisotropies in the cosmic microwave background for 20 years now with COBE, WMAP and now Planck, news that seems to have yet to reach Conservapedia.

They even try to deny the role relativity plays in GPS systems.  They cite something from the “Time Service Department, US Navy” which as near as I can tell, doesn’t exist (maybe they mean the U.S. Naval Observatory).  Typing their claim into google yields hits that lead to (surprise!) Conservapedia!  Claiming a non-existent agency said something is hardly proof (and the USNO did not say it either!)  It is easy to find details on the GPS use of relativity.

I believe I have found where this comes from, a paper titled, “GPS AND RELATIVITY: AN ENGINEERING OVERVIEW” by .Henry F. Fliegel and Raymond S. DiEsposti.

First, the original quote in context.

“The Operational Control System (OCS) of the Global Positioning System (GPS) does not
include the rigorous transformations between coordinate systems that Einstein’s general theory
of relativity would seem to require – transformations to and from the individual space vehicles
(SVs), the Monitor Stations (MSs), and the users on the surface of the rotating earth, and the
geocentric Earth Centered Inertial System (ECI) in which the SV orbits are calculated. There
is a very good reason for the omission: the effects of relativity, where they are different from
the effects predicted by classical mechanics and electromagnetic theory, are too small to matter
– less than one centimeter, for users on or near the earth.”

If I may further quote from the paper,

“If two observers determine what intuitively we call the same quantity – the distance between two points, or the time interval between two events – they will measure different lengths and times, if (1) they are moving with respect to each other, (2) one is higher or lower than another in a gravitational field, or (3) one is accelerating with respect to the other. Users of GPS encounter all three effects, and should correct their measurements accordingly, by formulas which we now explain.”

Allow me to translate…there are lots of relativity effects GPS must take into account…but there is ONE really small correction due to a coordinate system change that is too small to matter.

I could go through and do the same analysis for all the claims, but that would be a waste of my time (and who would want to read the resulting document?)

Einstein’s theories of Special and General Relativity have passed some of the most rigorous tests in any field of science.  There are still puzzles to be worked out, but Conservapedia is zero for 24 in understanding them.

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August 10, 2010 - Posted by | Politics

2 Comments »

  1. Just FYI, this page has been edited A LOT today. The reference to GPS is totally gone. WIN! Maybe I should keep blogging about it!

    Comment by halfastro | August 11, 2010 | Reply

  2. Wow! WordPress.com rocks! I just posted an article http://science1.wordpress.com/2011/04/11/time-in-physics/ about GPS and GR and related posts led to your article.

    My concern with your argument is that, I am not interested in how well GR may have been tested over and over again by academic physicists. . . That’s a different topic. No. I am interested to see an evidence in the form of actual residuals from GPS satellite data and code. Only this, will be a scientific evidence. Do you such data? Otherwise, you are repeating a myth first invented by Neil Ashby.

    Comment by zeynel | April 12, 2011 | Reply


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