A new world
- Hi! - said the
young girl-electron
Elna with
joy to the old woman-electron close to her -
Why are we going so fast? Is there a great party down there?
A big group
of electrons, a "beam" as Humans loved to call it, was travelling at astonishing
speed towards a remote point. The beam, inside a metal pipe, was driven by a
strange
force that speeded it up faster and faster. Elna, a pretty girl-electron
with long blond hair and blue eyes, was part of the group.
(Credit:
Adapted from:
SCIENZE,
quaderni,
117, dic. 2000, 30)
The old woman-electron looked at her rather surprised, then in a kind voice said: -My name is Nega. Where are you from? How did you arrive here with us?
- I lived on
the surface of an object.yes, something Humans call metal. There I had
many friends, all electrons just like me. I belonged to a group called, for some
reason,
conduction electrons. There we moved, played and ran in every
direction, but we could never exit. Then, one day, some strange flying objects
(which the older electrons called "photons") came from the space. There was
a general flight of panic. I remember one of these photons, a real brute, bumped
into me or probably punched me so hard that I went off the metal. Now I'm
here, feeling a little stunned. But I suppose
I should really thank that brute because I was fed up of always staying in the same place and I wanted to change my life. Now I'm
free and happy.
- Free? - whispered Nega perplexed in a motherly tone. - You really are young and inexperienced.
- Why? - asked Elna politely, despite her injuries. - I was bored doing the same things every day, always seeing the same faces. Now, at least for a while, I can see new things, make new friends, and mostly I can freely do what I want.
- You really think so? - asked Nega thoughtfully. - Here we go very fast, but we are not free. Try to move in a direction other than the one we are all moving in at the moment. Can you do it?
Elna tried many times, then a little angrily answered: - No, I can't.
- Inside this
pipe there is "something", that Humans call a
magnetic field, that forces
you to travel towards that point far away, the Great Party, as you called
it. Furthermore there is also another "thing", that Humans call an
electric
field, that speeds you up more and more.
- So I'm a prisoner! - exclaimed Elna, feeling threatened.
- No! no! You aren't! - reassured Nega noticing her fear. - Now you can travel and see new things. You have simply jumped into a "new World".
Though she was puzzled, Elna felt cheered up by those words.
- Listen, little girl, - Nega went on smiling - oh, sorry, Elna.you seem so young to me. Life has taught me a lot and there are some things I think you should know before arriving at the Great Party.
- You must realise that, with the jump you made, you entered a very different World from yours. In this new World objects travel at very high speeds and many of your daily experiences are no longer valid.
- I understand. Even here I have to make sure I don't eat too much ice-cream so I don't put on weight - said Elna joking.
- No, unfortunately here you become heavier even without eating ice-creams.
Elna looked at her in surprise.
- Yes - continued Nega - I think you know that the energy of a body increases when speed increases.
- So what? - hurried Elna impatiently.
-
So.let's
reason together.Think of the formula, which today everyone knows, that links
the energy E to the mass m of a body, that is E=mc2,
where c is a constant, the speed of light. So,.as we just
said, if the energy of a body increases when speed increases, from this formula
you get that when the speed increases, the actual mass of the body
increases too. And this effect becomes important only at high speed; mass increase exists
at low speed too, but you don't notice it.
Shall I
give you an example? Your friends muons, when travelling at 99,9 per
cent of the speed of light, are much heavier than their stationary
(i.e. at rest) equals. In fact, they are about 22 times heavier!
- Really? No, no, I don't want to get fatter! - exclaimed Elna in anger. - And then, what does the speed of light have to do with all this?