# Tell My Dog What She Got Wrong: How to Teach Relativity to Your Dog Errata

In comments to yesterday’s post, Andrew G asked:

Speaking of writing, is there an errata list somewhere for “How to teach relativity to your dog“?

No, but there probably should be. I believe there’s an error in one of Maxwell’s equations (an incorrect sign, though you should’ve seen the first typeset version…), but given the length and complexity of the book, there are almost certainly other mistakes. So, if you’ve spotted an error, in physics, grammar, or anything else, leave a comment here, and I’ll compile a list of things to fix if we ever get the chance.

## Comments

1. #1 Andrew G.
April 1, 2012

I think there’s a B where there should be an E in the fourth of Maxwell’s equations, as well as an incorrect sign. (Not being a physicist by trade, I didn’t spot the sign error, but the B vs. E mistake makes the equations not match the text description, provoking a “whut?” from my inner mathematician.)

The other error (sort of) that struck me is on p86:

“It only seems that way, because you’ve lost track of who sees what. No observer sees both a 3m leash and a 1.3m bridge. Anson sees the bridge being short, and the leash long, while his humans see the bridge at its usual length and the leash as only 2m long.”

The second sentence contradicts the third, and most of the preceding paragraph, all of which explain that Anson does indeed see a 3m leash and a 1.3m bridge. No-one sees a 3m leash fitting under a 1.3m bridge (Anson sees it not fitting, and the humans see the leash as 2m), but that’s not what it says there.

2. #2 Jean Gobin
April 2, 2012

Good Morning Professor, the last of the Maxwell’s equation on page 34 of “How to teach relativity to your dog” is wrong: on the right hand side, E should appear instead of B, and with a positive sign.

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