Stephen Hawking's Universe - EP3: Cosmic Alchemy (5/ 5)

[zacktillery]

Absolutely beautiful.

[mikeborja1]

this is a miracle universe

[wildsabes]

what is the anti-particle of a neutron?

For neutrons to have come into existance they must have anti-paticle, as I understand.

And a particle's anti-paticle is defined by having the same mass but the opposite electrical charge...

or is it, in the case of the neutron, a variation in nuclear force?

I'm a 15 year old boy trying to make sense of reality, please help :P

[farticlephysicist]

@wildsabes

The antiparticle to the neutron is the antineutron which is composed of antiquarks. Neither the antineutron nor the neutron have a net electrical charge; however, they do differ in their bayron number and their magnetic moments are opposite to one another

[wildsabes]

@farticlephysicist thx for the explanation, it is very much appreciated

[loselbuliros]

Hi tonnyzmglm, sorry for my naive question, if in the beginning of the universe, matter and anti-matter were formed by pure energy, where did the energy itself come from? or this is like the egg-chicken problem? :)

[wildsabes]

@loselbuliros

It is close to the chicken-egg problem, though we can make the first thing, as far as we know, smaller and smaller.

There is a temperature 10^10 K at which electrons spontaniously 'come into existance'

at 10^13 K protons and neutrons appear.

Temperature is movement, so there would have to be only a few particles, that by colliding would make each other move faster, untill the effect would be a temperature where more particles started to 'pop up'

[goldensleeves]

At 7:58, he says "protons and neutrons started to bind"... Why did they do that??

[tonyzmglm]

because after the universe cooled the collisions between them lacked energy for the protons and neutrons to scape from the hold of intramolecular forces, so they bind toguether. picture water, as its heated it gains energy, moving faster and faster, then each water molecule gain enough energy for them to escape from its liquid state, forming vapour,

[tonyzmglm]

now imagine if heating the vapour even more, 10E6s of times more than you did at the begining, until the energy in each proton and neutron is enough for them to escape the forces binding them toguether in a similar way as water did. now imagine the oposite as the loose water molecules they will bind toguether into water droplets, similar to as when the universe cooled, the protons and neutrons bind toguether forming nuclei.

[goldensleeves]

Thanks, tonyzmglm... That makes sense

[tonyzmglm]

your welcome and sorry you got a reply this late heheh

[Zee96969696]

because they were attracted to each other

[goldensleeves]

Why?? Protons are positively charged... neutrons are neutrally charged... why would they be attracted to each other? Gravity?? Gravity would be miniscule at such a microscopic level. Why would they be attracted to each other?

[Zee96969696]

its because protons look good to neutrons and neutrons look good to protons, dont u get it, dont u learn anything from discovery channel?

[goldensleeves]

Apparently, you do not know the answer. I assume that is why you are making a joke out of answering the question. Oh well, have a good day/night.

[LtBatman11]

its because of stong nuclear force. one of the 4 fundemental forces.

[tbillinger]

What Zee said actually makes sense.

Think of how a magnet is attracted to ferrous metals, somethign which has neither a north or south pole.

If something lacks charge, it attracts both negative charges, and positive charges. In the case of magnetism, something that is ferrous attracts both the south and the north pole of a magnet.

[sbergman27]

@tbillinger : No. A particle with neutral charge neither attracts nor repels charged particles. That's basic "Coulob's Law". F=k(q1*q2)/r^2. If either q is 0, then the force between them is 0. The reason iron is attracted to both poles of a magnet is that the electrons in it are free to move around. A chunk of iron becomes polar in the presence of an electromagnetic field, The polarization direction depends on whether it is near the north or south pole of the magnet.

[tbillinger]

@sbergman27 I stand corrected. Learn something new every day.

[sbergman27]

@tbillinger : Well... it looks like I managed to misspell "Coulomb" in my post. ;-)

[WOWFPS]

yeah, thank you for uploading

[lilbromarky1]

thx for posting. I loved it

[SarahFraser86]

thanks so much for uploading I'm really enjoying the series!

[spliffidge]

hear hear.

[keyan99]

the map of matter and anti-matter, at around like 5:30, was looking awfully phallic.

[e119511]

very nice documentary. i think everybody should watch that documentary and learn something about the world cosmos and everything we see