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What i wanna do in this video

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is give a very high level overview

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of the 4 fundamental forces of the universe

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And I'm gonna start with gravity.

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and it might surprise some of you

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that gravity is actually the weakest

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of the 4 fundamental forces

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And that is surpring cause thats what keeps us glued,

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well not glued, but what keeps us from

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jumping off the planet

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its what keeps the moon in orbit around the earth

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the earth in orbit around the sun

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the sun in orbit around the center of milky way galaxy.

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So it is a little bit surpring that it is actually the weakest

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of the forces. and that starts to make sense when actually you

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think about things in more of a human scale or a molecular scale

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or even an atomic scale. Even on a human scale

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your computer monitor and you have some gravitational

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attraction, but you don't notice it or your cell phone and your

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wallet, there is some gravitational attraction, but you don't see

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them drawn to each other the way you might see 2 magnets

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drawn to each other or repelled from each other.

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and if you go even for a smaller scale you see that it matters

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even less, we don even talk about gravity in chemistry, although

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the gravity is there. but at those scales the other forces really start to dominate

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So the gravity is our weakest.

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If we move up a little bit from that, we get,

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and this is maybe the hardest force for us to visualise, at least the hardest force for me,

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is actually the weak force, sometimes called the weak interaction

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and it's what's responsible for radiactive decay,

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in particular beta minus and beta plus decay

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and just to give you an example of a weak interaction

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if I had some cesium 137

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137 means that it has 137 nucleons

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a nucleon is either a proton or a neutron

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you add up the protons and neutrons of cesium, you get 137

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and it is cesium because it has exactly 65 protons.

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Now, the weak interaction is what's responsible for one of its neutrons,

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essentially for one of its quarks flipping and turning into a proton

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and I'm not going to detail of what a quark is, and all of that

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and the math can get pretty hairy

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but i want to give you an example of what a weak interaction does

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so if one of these neutrons turns into a proton

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we're going to have one extra proton

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but we're going to have the same number of nucleons

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instead of an extra neutron you have an extra proton here

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and now it is a different atom it is now barium

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and in that flipping, it will actually emit an electon

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and, an anti-electron neutrino

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I'm not going to go into the details of what anti-electron neutrino is

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these are fundamental particles

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but this is just what the weak interaction is

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it's not something that is really obvoius to us

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it's not just these traditional things pulling and pushing away from each other

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like we associate with the other forces

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Now, the next stronger force

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and just to give you a sense of how weak gravity is

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even relative to the weak interaction

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the weak interaction is 10^25 times the strength of gravity

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and you might be thinking:

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if this is so strong, how come this does not operate on planets

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or us relative to the earth

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why doesn't this apply to intergalactical distances

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the way gravity does

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and the reason is

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weak interaction really applies to very small distances

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so it can be much stronger than gravity

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but it only applies over subatomic scale

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you go anything beyond that,

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it kind of disappears as an actual force, or interaction

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And now, the next force up the hierarchy,

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wich is the one we are more familliar with

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it is something that actually dominates most of the chemistry that we deal with

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and the electromagnetism that we deal with

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And that is, the electromagnetic force.

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And just to give you a sense, this is 10^36 times the strength of gravity.

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So it kind of puts the weak force in its place

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it's 10^12 times stronger than the weak force

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these are huge numbers that we are talking about

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either this relative to that, or this relative to the gravity

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so you might be saying, the electromagnetic force,

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that is unbelievably strong, why doesn't that apply over

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over these macro scales, like gravity

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lemme write it down, macro scales

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why doesn't it apply to macro scales?

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and actually

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there is norhing about the electromagnetic force why it can't

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or it actually does apply overlarge distances.

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The reality though, is that

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you don't have such concentrations of either coulomb charges

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or magnetism,

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the way you do mass

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so mass, since you have such huge concentrations,

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it can operate over huge, huge distances

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even though it's way way way weaker than the electromagnetic force

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The electromagnetic force, what happens,

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because it is attractive and repulsive,

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it tends to sort itself out

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sou you don't have these huge, huge concentrations of charge

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Now, the other thing you might be wondering,

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why is it called the electromagnetic force?

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In our everyday life,

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there's things like the coulomb force

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or the electrostatic force, which we're familiar with:

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positive charges, or like charges want to repel

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if both of these were negative, the same thing would be happenning

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and different charges like to attract

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we've seen this before, this is the coulomb force,

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or the electrostatic force

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and then on the other side of the.. word i guess

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you have the 'magnetic' part

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and magnets, you know you've had played with magnets on you fridge,

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if they're the same side of the magnet,

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they're gonna repel each other

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if they're the opposite sides, opposite poles,

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they're gonna attract each other

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who why is it called one force?

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And it's called one force,

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and once again, I'm not going to go into detail here,

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it's called one force , because it turns out that

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the coulomb force (electrostatic force) and magnetic force

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are actually the same thing

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viewed in different frame of reference

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so I won't go into much detail,

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but just keep that in the back of your mind

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that they are connected

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In the future video, I'm going (????)

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of how they're connected (????)

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It's more apparent when they're moving,

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when the charges are moving in relativistic frames, and you have..

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Just keep in mind that they are really the same force,

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just viewed from different frames of reference

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Now, the strongest of the forces,

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it's probably the best named of them all,

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and that's the strong force

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and although, you've probably haven't seen this yet in chemistry classes

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it actually applies very strongly in chemistry

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because when you first learn about atoms, lemme draw a helium atom

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A helium atoms ha two protons in his nucleus

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and it has two neutrons,

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and the it also has two electrons circulating around

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So it has electron, and I can draw the electron much smaller

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Well, I won't try to so anything in relative size,

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but it has two electrons floating around.

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And one question, that may or may not have jumped into your mind

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when you first saw this model of an atom

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is like: I see why electrons are attracted to the nucleus,

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It has negative coulomb charge,

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the nucleus has positive coulomb charge,

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but what's not so obvious,

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and what tends to sometimes not be explained in chemistry classes is:

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These two positive charges are sitting right next to each other!

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If the electromagnetic force was the only force in play

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if the coulomb force was the only thing happening,

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these guys would just run away form each other

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they would repel each other

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and so, the only reason that they're able to stick to each other

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is that there's even stronger force

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than the electromagnetic force

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operating at these very, very small distances

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so if you get two of these protons close enough together,

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and the strong force applies only over very, very small distances

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subatomic, or I should even say sub-nucleic distances

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then the strong interaction comes into play

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so then you have the strong interaction actually

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keeping these charges together

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And once again, just keep it in mind

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relative to gravity, it is 10^38 times the strength gravity of

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or it's about 100 times stronger than the electromagnetic force

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So once again, the reason you don't see the strong force,

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which is the strongest of all forces,

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or the weak interaction,

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applying over huge scales,

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is that their strength dies off super, super fast

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even when you start to go into large radius nuclei of atoms

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the strength starts to die off, especially for the strong force.

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The reason you don't see the electromagnetic force applying over large distances,

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even though in theory it can, like gravity,

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is that you don't see the type of charge concentration

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the way you see mass concentrations in the universe

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because the charge concentrations tend to sort themseleves out,

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they tend to equalize

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If I have a huge positive charge there and a huge negative charge there,

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they will attract each other and then they become

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essentially a big lump of neutral charge,

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and once they're a big lump of neutral charge,

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they won't interact with anything else.

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Gravity, if you have one mass, and another mass, they attract each other

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then you have a mass that's even better at attracting other masses

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and so it'll keep attracting things to it.

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So kind of snowball-like process

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and that's why gravity can operate some of these

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really, really large objects in our universe

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and the universe as a whole