Anonymous asked in Science & MathematicsMathematics · 1 decade ago

Can you explain Em=2 as if I were retarded..but more importantly, what does light squared mean?

I know energy and mass are supposed to be "equivalent" in this theory..but what is the significance of light having to be squared? I have looked and searched and I see no explanation of this online. I don't know why light must be "squared".

If energy travels at the speed of light.. what is the point of using the word squared?


To the person who first answered: that would only make SENSE to me if I had taken a course on this, which I have not. Pretend Im retarded, maybe that will help you explain it to me. My question is why light needs to be squared, what does "squared light" mean, and what does it have to do with energy and mass being equivalent.

Giving me math equations won't help. Im still trying to figure out fractions. LOLOLOL.

Update 2:

Keep in mind I havent been in school in years, much less taken math classes, giving me equations is not going to make me understand.

3 Answers

  • 1 decade ago
    Favorite Answer


    c is the speed of light

    It's just a matter of how energy is measured. If we defined the measurement of energy differently, then the unit conversion factor of c² would disappear.

    If we used a more natural unit system where speed is relative to the speed of light instead of relative to "meters", with the speed of light itself being "1", then the formula would become:

    E = m·(1)²

    E = m

    So it means that mass and energy are equivalent (even though our systems measure them differently), as c² is an unchanging value. It's just a conversion between units, such as between meters and feet.


    I'm not sure if your reaction was partially in response to my post, but... It's hard to explain it without an equation. Essentially all it does is make a unit conversion.

    Mass is measured in "kilograms"

    Energy is measured in joules, which are "kilograms meter squared per second squared"

    So if you want to convert "kg" into "kg·m²/s²", you need to multiply by "meters squared per second squared".

    "Meters per second" is given by distance/time, just like "miles per hour" or "kilometers per hour".

    Distance over time is velocity, a speed. If you square meters per second (m/s), you get meters squared per second squared (m²/s²).

    In this case, energy depends on the speed of light, since energy takes the form of light (this means not just visible light but radio waves, heat, magnetics, etc.). So the amount of energy stored in mass is expressed by multiplying it by the speed of light squared.

    This is just a unit conversion though, as mass and energy could be measured in the same way, where one "cube" of mass was equal to one "unit" of energy. In that case, the formula would just be E = m

    But in order to get from "kg" to "kg·m²/s²", there still should be a method of conversion.

  • Awms A
    Lv 7
    1 decade ago

    To tell you the truth, when I took a (short) class on relativity and quantum mechanics, I didn't truly understand it.

    However, it sounds like you may be misunderstanding some parts I _can_ explain:

    E = m c^2

    is stating that the equivalent energy for a given mass is found by multiplying the mass by the speed of light (in a vacuum), squared.

    So we're not actually squaring light (that wouldn't make much sense). Rather, we're taking the speed light travels and we're squaring that.

  • 1 decade ago

    It's a matter of getting the units right. Let's say energy is X. Mass is 1g. The speed of light is 3x10⁸m/s. So...

    X·1g = (3x10⁸m/s)²

    X·1g = 9x10¹⁶m²/s²

    X = 9x10¹⁶m²/gs²

    When you work out units of work, you will end up with these same units. There is a conversion factor, for instance, from m²/gs² to Joules.

    Or more straightforwardly, kinetic energy comes in this measurement, too.

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