# If energy is just the ability to do something, how can you have physical strings?

## Main Question or Discussion Point

I was watching a video on string theory and they claim that its all vibrating strands of energy. I thought energy was just a property of the system, not a physical entity. So do they mean something else by "energy"?

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Are you familiar with Einstein? He was a clever guy... should read about him

Drakkith
Staff Emeritus
I was watching a video on string theory and they claim that its all vibrating strands of energy. I thought energy was just a property of the system, not a physical entity. So do they mean something else by "energy"?
An interesting question. Perhaps they call it that for lack of a better term?

It's a great question... if the current view is that unmeasured standard quantum particles don't have particular attributes for position, velocity, momentum, energy, etc , how much greater the problem of characterizing the string as having a vibration (which classically entails all those attributes)?
The size of a string compared to a proton diameter is about the same magnitude as the size of a man to the distance from here to Andromeda galaxy... the uncertainty principle would seem to make any possible "vibration" attribute of a string impossible.
I'm sure the string theorists are using the math to work with different kinds of abstract attributes altogether, and "vibration" is more like the nickname for an abstract mathematical attribute - sort of like "spin" is the nickname for intrinsic angular momentum of something not thought to be actually spinning...

jtbell
Mentor
I was watching a video on string theory and they claim that its all vibrating strands of energy.
Which video? Many people use sloppy language when trying to present things like string theory on a non-mathematical level to people who aren't physicists.

It was a briane greene documentary for nova

It was a briane greene documentary for nova
Ah, the Elegant Universe. As another poster said, it's probably "energy" for lack of a better word. In fact, I'm not sure if, assuming String Theory, there's a meaningful way to describe what they're made of.