Friday, February 24, 2006

ENIAC

ENIAC is considered the world's first computer. An amazing machine--primitive by today's standards. Then again, most things created in 1946 are primitive by today's standards. Sixty years of progress will do that to you.

Here's a very interesting post on ENIAC. It's from Photon Courier, which I'm proud to have on my blogroll.

I remember listening to a talk by Commodore (I love that rank) Grace Hopper, USN, for some class I took at West Point. I don't even remember which course. Anyway, Commodore Hopper talked about her work on ENIAC, a fascinating first-person story from a "little old lady" told as only a little old lady could. What I remember most about this talk was her description of a nanosecond. She couldn't grasp how small a timeframe a nanosecond was, so she calculated how far light (or electricity) would travel in a nanosecond. It came out to about 11.8", and she cut a wire that long to help her "see" a nanosecond. As we left the auditorium, she handed each of us a "nanosecond".

I've long since lost mine. Shame.

7 comments:

David said...

Admiral Hopper, eventually. She was recalled after retirement to help unsnarl the logistics systems mess in Vietnam. There's now a Navy vessel (frigate?) named after her.

Thanks for the link.

Darren said...

Yes, she did eventually make Admiral.

"Commodore" was a 1-star flag rank, but Navy types didn't like it because a commodore was addressed "commodore" and not "admiral" as 1-star generals are addressed as "general". So the navy got rid of of the "commodore" rank. 1-stars in the navy are now known as "Rear Admiral, Lower Half" while 2-stars are "Rear Admiral, Upper Half".

I think I'd rather be called "Commodore."

Her speech to us was in the mid-80s (83-87, although most assuredly in the latter part of that spectrum) and she was a commodore at that time.

Edward said...

Electric current usually moves about 1/3 the speed of light, I thought.

Darren said...

Edward, I've never learned that. Now I have research to do.

Dick said...

Darren,
Here is a good Army reference to information about ENIAC.
http://www.amc.army.mil/amc/ho/studies/eniac.html

I was invited 10 years ago to attend Aberdeen Proving Ground's ceremonies celebrating the 50th anniversary of ENIAC, and a private reception afterwards for the primary invitees. Herman Goldstine (PhD, 1st Lieutenant then) who had been the Army Project Officer (imagine that today, when we would not trust such responsibilities to less than a General Officer!) was present for the ceremony. He died just a couple of years ago now. He wrote a very interesting book, "The Computer, from Pascal to von Neumann" which I recommend. Got to meet him, von Neumann's children, and Colonel Gillon's wife and children (Goldstine's boss). A wonderful day!
Dick

Old Math said...

When we talk about the speed of light we are usually referring to the speed of light in a vacuum. The speed of light in a transparent material is less - this is what causes refraction, the phenomena that allows my eyeglasses to work (to say nothing of the lens of my eye).

Conduction of electricity in a wire is a little more complicated. The average speed of a given electron in the wire is very slow, but the electric potential along the length of the wire starts electrons moving very quickly and this wave propagates at a speed close to the speed of light. The physical configuration effects the speed, it can be as low as 66% of the speed of light.

See:

http://en.wikipedia.org/wiki/Electrical_current
http://en.wikipedia.org/wiki/Velocity_factor
http://en.wikipedia.org/wiki/Speed_of_light#Interaction_with_transparent_materials

(By the way I would never trust anything wikipedia has to say about historical or social issues without additional sources (for example congressional biographies) but It seems to be an excellent trustworthy source for physical science and mathematics).

Darren said...

Old Math: Of course you're correct.

I remember a discussion with a friend in physics class in 12th grade. We were learning about how light slows down when passing through media, and I wondered if there might be some medium that would slow the transmission of light down to something we could actually see, something on the order of mm per second. My friend replied, "There are some things that will slow it down completely. Like lead."

To my 17/18 year old mind, that was hilarious. Maybe it was in the delivery, because it's certainly not that funny now.