NPR: Egg on Your Face?

Egg on Your Face?

Can't stand these eggs.

Getty Images

Did you feel any different at 12:48 a.m. EST? Feel like the laws of physics changed?

The vernal equinox today marks the beginning of spring and is characterized by equal parts day and night. Every year, when the equinox rolls around, a rumor resurfaces. It says that you can stand a raw egg on its end today -- and today only.

Is gravity so misunderstood that it's conceivable it could change the rules on us for a single day? Even if this were true, why could only eggs stand on end? Why not eggplants? Or pickles? And why not on the autumnal equinox too?

Fact is, gravity is the same today as it always was; perhaps it just needs a better public relations campaign. You can stand an egg on its end any day of the week, month, or year. Try it. This guy sure did!

Now, go smell the flowers and celebrate spring the old-fashioned way.

Summer Ash

7:00 AM ET | 03-20-2008 | permalink

Comments (Send a comment)

It's not true that gravity is always the same, gravity differs depending on your location relative to the equator and your position relative to sea level. The closer to the equator you are, the lower the gravitational force, and the closer you are to sea level, the greater the gravitational force.

The real question is whether higher gravity or lower gravity would allow you to stand an egg on its end.

Sent by Greg | 9:29 AM ET | 03-20-2008

Greg - I didn't say the force of gravity was always the same. What I implied was that gravity acts the same (F = mMG/r^2). Yes, r will differ depending on where you are on the surface of the earth, but that is in no way related the vernal equinox (for all intents and purposes).

And no special exceptions are made for eggs! You can stand them on end whether you are in Death Valley or on top of Mount Everest. If you want to talk other planets or asteroids, that's a different story...

Sent by Summer | 1:21 PM ET | 03-20-2008

Well, I didn't mean attempting the egg trick anywhere on Earth, since the fluctuation is pretty small.

Also, why are you using a MOND equation to express gravitational force? We're on Earth, lady!

Sent by Greg | 2:45 PM ET | 03-20-2008

AH! I love the formula. It gave me something interesting to research. Some wacky explanations I found go on about how F = ma where m is inertial mass. The m in your gravitational mass equation and the m in the inertial mass equation are the same value. So, in a really simplistic way, does this mean that the egg has to be symmetrical? The way I'm reading it, it seems that people think the world needs to be all balanced at its center but really it's the egg that has to be symmetrically balanced around its center. Am I reading these papers and textbook excerpts correctly?

(>_

Sent by Sarah Lee | 3:33 PM ET | 03-20-2008

Oh, or maybe you don't need a symmetrical egg, you just need to find the symmetrical center so tilting it until it stands on end would work, too? I'd check the video or article you linked to but it's blocked at work...which is where I am now.

Sent by Sarah Lee | 3:39 PM ET | 03-20-2008

Her equation doesn't actually apply on Earth.

In hers, the "m" represents the mass of a star, and the "M" represents the mass of a spiral galaxy. The equation is meant to account for the flattening of a galaxy's rotational curve, which means that the stars at the outer edges of a spiral galaxy SHOULD move more slowly, but don't. It has no relation to Earth-related physics.

Sent by Greg | 5:02 PM ET | 03-20-2008

Weird. I took 'm' to be the mass of the object (in this case, egg) and 'M' to be the mass of whatever is creating the gravity (in this case, Earth).

Sent by Sarah Lee | 10:16 PM ET | 03-20-2008

Sorry for the delayed response!
Greg - my equation is not a MOND equation, it's the basic form of Newton's law of universal gravitation (http://snurl.com/232rk) and it applies to any two points of mass.
Sara Lee - your interpretation of the m's is correct and my equation works just fine on Earth and if you approximate an egg as a spherical body. Yes, they are clearly not spherical, but making simplifications to see the big picture is what we do sometimes. Otherwise you can get lost in the details and never find your way out! :)

Sent by Summer | 1:56 PM ET | 03-31-2008

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