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How do we pronounce E = mc²? This is a physics equation.

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It's "physics". Or is it? (Yes, I'm about to go on a nitpicking spree, but then again, this is about "English Language and Usage", right?) – Jürgen A. Erhard Jan 26 '11 at 13:27
@CJM: I assume they simply knocked 'ematics' off the end, whereas the more subtle and generally better-looking Brits excised 'ematic' leaving 's' intact. ;) – user3444 Jan 26 '11 at 14:00
@ElendilTheTall: I resent your implication that Brits are subtler and better-looking. ;) – Jon Purdy Jan 26 '11 at 18:24
@ElendilTheTall: Ah, but the colonies are filled with the most subtle and attractive of all; we are simply better at hiding it than you Brits, who wear your hearts on the outside! But, lest I inadvertently harm you with my elegant nuance and startlingly good looks, I shan't argue. :) – Jon Purdy Jan 26 '11 at 18:35
Here is the sound bite of Einstein stating the equation (he says "E is equal to m c-squared"): youtube.com/watch?v=CC7Sg41Bp-U – Joey Adams Jan 26 '11 at 18:36
up vote 29 down vote accepted

You read this as E equals M C squared, with the three letters pronounced as you would when reading the alphabet.

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For a video demonstration of this pronunciation, see 1:55 onwards of: youtube.com/watch?v=CZqUNEHYZgQ – onestop Jan 26 '11 at 18:30
Or here: aip.org/history/einstein/sound/voice1.mp3 – ghoppe Mar 5 '11 at 16:35
@ghoppe Einstein says: "E is equal M C square". – Hugo Oct 31 '11 at 21:36
@Hugo Yep, that's right :) – ghoppe Nov 1 '11 at 2:48

The "=" sign is read as "equals" or "is equal to", depending on your culture.
(In the latter case, "is equal to" is such a common phrase all through school that it's typically read as one word: "izziqualtu".)

The "c2" could rarely be "c [raised] to the power of 2", but is almost always "c squared" (or "c square").

Thus, "ee equals em see square[d]" or "e is equal to em see square[d]".

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@Jasper Loy: c to the second (power) is also (more?) common. – Jon Purdy Jan 26 '11 at 18:26
LOL at "izziqualtu"! – Jimi Oke Jan 27 '11 at 4:16
@Jimi: Heh. It's even conceivable that someone made it through school without ever resolving the "word" izziqualtu into three words. It was certainly very very late in my childhood that I had the epiphany that the postfix multiplication operator "zar" from our multiplication tables — as in "three one zar three", "three two zar six" (we even used to ask each other "what is seven nine zar?" and the like) — was merely "three ones are three" etc. – ShreevatsaR Jan 27 '11 at 4:51
Ha ha ha:) +1 for "izziqualtu" and "zar". And most people I know say "two six zar twelve" and not "two sixes are twelve".:) – Tragicomic Feb 1 '11 at 10:59

Alternatively, one could say

Energy is the mass times the square of the speed of light in a vacuum.

If you are so inclined.

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If you listen to this audio clip of Albert Einstein speaking in 1947, you can hear him say it as "E is equal M C square" (with letters as ee, em, see).

But nowadays it's normally pronounced as Jasper Loy answered: E equals M C squared.

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Very simple you just go on speaking each word and symbol as they are. So that makes it : "E is equal to M C Square "

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Normally, that's "Ee equals emcee squared." – The Raven Oct 31 '11 at 19:51

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