Original URL: http://www.theregister.co.uk/2012/10/11/google_shrinks_the_world/

## It’s official: Google shrinks the world!

To the size of a London bus, roughly

Posted in Science, 11th October 2012 04:47 GMT

An anonymous reader has pointed us to this slip in Google Calculator: someone – or something – picked the wrong units for Earth’s escape velocity.

If you ask Google – using the search term "Earth Escape Velocity" – and you’ll get the result in the shot below.

Is that a comma or a decimal? Google's response to a search for

Earth's escape velocity

*El Reg* has confirmed the result for ourselves.

It’s very nearly almost right, except for the pesky presence of the letter “k”, as in “kilometres per second”. Actually, the correct value for Earth’s escape velocity is 11,190 (with a little rounding) *meters* per second.

Wikipedia gets the value right, here, or if you want a more authoritative source, there’s NASA, here.

*The Register* just hopes that no cramming first-year university students – or last-year high school students – rely on this value in their studies, because, as our correspondent pointed out, it leads to some humorous outcomes.

The equation for calculating escape velocity takes us back to Newton: it’s the square root of (2*G*M/r), where G is the gravitational constant, M is the mass of the Earth, and r is the radius.

Asked to work it out from scratch, and Google is quite happy and accurate. If you want to prove it, put in sqrt((2 * gravitational constant * mass of Earth) / radius of Earth) and see what happens.

### sqrt((2 * gravitational constant * mass of Earth) / radius of Earth) = 11 178.8391 m /s

Orl Korrect, as they might say …

If, however, you reverse Google’s original 11,190 km/sec, you’ll get quite a different result for the radius of Earth:

**(2 * gravitational constant * mass of Earth) / ((11 190 (km / s))^2) = 6.36538334 metres**

Earth's radius, calculated for Google's stated escape velocity

…a radius roughly the length of a London bus (in classic *Register* units).

Which is a pity, because that leaves us only a couple of alternatives. Either there are some students out there in grave danger of mucking up an assignment or exam; or we ran out of space a long time ago. Reversing the equation to calculate Earth’s mass is even more amusing. As our correspondent noted:

“The calculated earth mass based on Google's escape velocity value would be 1,000,000 times greater than the actual Earth mass - and the human race would likely be a puddle on the earth surface due to the surface gravity being 1000000g”.

A couple of attempts have been made to draw Google’s attention to the error, here and here for example.

The poster of the latter of these links wonders if it’s a localisation error – putting a European comma in place of the decimal point used in America, Australia and the UK. That might, indeed, make sense – since the same unit error occurs if you ask Google the escape velocity of the Sun. Google presents 617,700 km/s as the solar escape velocity, rather than 617.7 km/s. ®

### Bootnote

Fire up the standards converter for the altogether more accurate *El Reg* official units of measurement. Still not sure how they work? Check out our instructional video.