Velocity of Light?

[Chesterton]

I came across an old newsreel or something, of Albert Einstein reading his E=mc2 equation aloud. He refers to c as "the velocity of light". I've never heard that before, I've always heard it was the speed of light. Why would he say that? Perhaps it doesn't matter for that particular equation?

 

[HTacianas]

I came across an old newsreel or something, of Albert Einstein reading his E=mc2 equation aloud. He refers to c as "the velocity of light". I've never heard that before, I've always heard it was the speed of light. Why would he say that? Perhaps it doesn't matter for that particular equation?

I'm not sure if there is a difference. I have often used Velocity Of Propagation of light through optical fiber to locate faults but velocity and speed have always had the same meaning.

 

[yeshuaslavejeff]

I came across an old newsreel or something, of Albert Einstein reading his E=mc2 equation aloud. He refers to c as "the velocity of light". I've never heard that before, I've always heard it was the speed of light. Why would he say that? Perhaps it doesn't matter for that particular equation?

https://www.physicsclassroom.com/class/1DKin/Lesson-1/Speed-and-Velocity
Speed and Velocity
Speed and Velocity
Speed is a scalar quantity and does not keep track of direction; velocity is a vector quantity and is direction aware. Determining the Direction of the Velocity Vector The task of describing the direction of the velocity vector is easy.

 

[sfs]

I came across an old newsreel or something, of Albert Einstein reading his E=mc2 equation aloud. He refers to c as "the velocity of light". I've never heard that before, I've always heard it was the speed of light. Why would he say that? Perhaps it doesn't matter for that particular equation?

It doesn't matter for that equation since c is squared. Beyond that . . . sometimes physicists are sloppy in their language.

 

[Dave-W]

I came across an old newsreel or something, of Albert Einstein reading his E=mc2 equation aloud. He refers to c as "the velocity of light". I've never heard that before, I've always heard it was the speed of light. Why would he say that? Perhaps it doesn't matter for that particular equation?

English was not his first language.

 

[sfs]

English was not his first language.

And I don't believe German has such a distinction.

 

[Chesterton]

It doesn't matter for that equation since c is squared.

Ah, okay.

Beyond that . . . sometimes physicists are sloppy in their language.

I wondered about that but thought surely the premiere physicist in the world wouldn't have been sloppy...but then I saw his hair, so maybe you're right.

And I don't believe German has such a distinction.

I don't know. I'd be sorta surprised if a people that produced so many top-notch rocket scientists didn't make that distinction. Maybe @Nithavela will be kind enough to chime in.

 

[Nithavela]

Ah, okay.

I wondered about that but thought surely the premiere physicist in the world wouldn't have been sloppy...but then I saw his hair, so maybe you're right.

I don't know. I'd be sorta surprised if a people that produced so many top-notch rocket scientists didn't make that distinction. Maybe @Nithavela will be kind enough to chime in.

Speed of light is "Lichtgeschwindigkeit" in german. Licht means light and Geschwindigkeit means velocity and speed. There's no distinction between speed (general movement) and velocity (movement plus direction) in german.

Also, velocity of light is a valid expression.

Definition of VELOCITY OF LIGHT

 

[Chesterton]

Speed of light is "Lichtgeschwindigkeit" in german. Licht means light and Geschwindigkeit means velocity and speed. There's no distinction between speed (general movement) and velocity (movement plus direction) in german.

Interesting. Danke schön.

Also, velocity of light is a valid expression.

I know it is, it was just the first time in my life I'd heard it used in E=mc2.