물리학 힘, 에너지 및 양자역학의 기초

중력부터 에너지, 열역학, 전자기학, 원자, 상대성 이론, 양자역학에 이르기까지 물리학의 경이로움을 알아보세요. 이 놀라운 여정에 동참하세요!

### 물리학의 기초: 중력에서 양자역학까지: 물리학의 기초
* 🌌  아이작 뉴턴의 운동 법칙부터 시공간이 휘어지는 중력의 개념에 이르기까지 물리학의 기본 원리를 설명합니다.
* 🔭  에너지 절약, 에너지의 다양한 형태, 일과 에너지의 관계에 대해 설명합니다.
* 🔧  열역학, 엔트로피, 에너지의 전달, 온도와 열의 개념에 대해 자세히 알아보세요.
* ⚡  전하, 전류, 전압, 저항, 전기장과 자기장의 거동 등 전자기학의 기초에 대해 설명합니다.
* 🔬  원자의 구조, 표준 모델, 다양한 원소와 동위원소, 이온화 방사선의 개념에 대해 알아봅니다.
* 💡  빛의 파동-입자 이중성, 상대성 이론, 에너지와 질량의 관계에 대해 설명합니다.
* ☢️  핵에너지, 핵분열, 핵융합의 개념과 이러한 과정의 잠재적 위험성에 대한 경고가 다뤄집니다.
* 🌀  중첩, 불확정성 원리, 입자의 파동과 같은 양자역학 원리에 대해 자세히 설명합니다.

Hi! You’re on a rock. Floating in space. Surrounded by more rocks. And gas. And a bunch of nothing, mainly. Oh hey, look at that, the rocks are going around the gas. Hold on, what the heck, is going on here? To understand, let’s look a little bit of Physics. Wait, did I say a little bit? To find out what kind of magic this is, we’ll have to go back in time. Okay, not that far. Stop! Yeah. That’s perfect. This is gravity guy. But most people call him “Isaac Newton”. One important thing he said is that Force equals mass times acceleration. Now what do all these words even mean? Force is just a push or pull on something, in a certain direction. Mass tells you how much of something there is, and it’s also a measure of inertia, but we’ll get to that later, and acceleration is the derivative of velocity with respect

to time, but that’s too many big words for
my taste, so let’s just say it’s how fast velocity is changing. The key takeaway is that if you apply a Force
to a fixed mass, you get a predictable amount of acceleration. If you know all the forces acting on a basketball
mid-air, you can predict with 100% certainty if the ball will go in the hoop or your neighbour's
windshield. “Whoa, did an apple just fall on my head?” Yes Newton, it did. “That must have happened for a reason,”
said Newton, as he discovered that two masses attract one another, making the apple fall. Yes, even you, no matter how ugly you think
you are, attract pretty much the whole universe, at least a little bit. Hey, can you put that on paper? “Yup,” said Newton, who gave us the Law
of Universal Gravitation. In other words, how much two bodies pull on
each other, given their mass and distance.

times a constant. Bigger mass? Bigger pull. Bigger distance? Smaller pull. Actually, a lot smaller pull. You see, as the distance increases, the force gets smaller by the square. That, my friends, is the Inverse-Square Law. Gravity is also the reason why the planets in our solar system orbit the sun. They got their initial velocity when the solar system formed out of spinning gas, and since there’s nothing in space to stop them from moving, they’ll keep moving. Hey, that’s Newton’s first Law. The sun is so massive that the force of gravity keeps pulling the planets towards the sun, but the planets are fast enough to essentially fall towards the sun but miss it, and this goes on forever, creating a round orbit. Actually, that’s kind of a lie. Most orbits are not perfectly round but more egg-shaped, and Pluto’s orbit is just…a complete mess.

But you get the idea. In this case, the gravity is what we call a centripetal force. One thing many people confuse is mass and weight, and no, they are not the same. Mass tells you how much of this blob there is, and Weight is the force of Gravity the blob would feel. To make things clear, your mass would be the same on the earth and on the moon, but the “weight” you would perceive, is different, because the moon has a weaker gravitational pull, meaning, a weaker force acting on your mass. So really, you’re not overweight, you’re just on the wrong planet. Aight, enough about Newton, let’s break some stuff. If you ever dropped your phone, it might look like this: What the hell ground, why’d you do that? The answer is Energy. You know, the thing kids have after eating gummy bears. Energy has the unit Joule.

And it’s not like Force. It doesn’t
have a direction. It’s just a number that’s kind of chilling there as a property of a
thing. You see, there are two main kinds of energy:
Kinetic energy and potential energy. In plain English, energy of movement and
stored energy due to some circumstance. For example, when you held your phone, it
stored gravitational potential energy due to being held above the ground at a certain
height. Once you dropped it, the potential energy
was converted into kinetic energy as the phone fell. Then it smashed into the ground, and the phone
absorbed some of the energy making the screen go boom. Work is defined as Force applied over distance. For example,
if you lift an apple by 1 meter, you would have done about 1 Joule of work. This happened by converting chemical energy
stored in your body to gravitational potential energy stored in the apple.

As you may have noticed, Energy and Work have the same unit “Joule”. So they must be the same thing? Uhhh, No. Energy is the total amount of work that a thing could possibly do. Work is just the stuff that actually happened and required energy. You know, force applied over a distance, which most often implies converting energy from one form to another. If you try to lift a weight that’s too heavy for you, you’d feel like that took a bunch of work, right? Well, yes, but your feelings are invalid in the face of Physics! Mathematically, no work has been done! Because, work is a force applied over a distance. And since you didn’t move the weight at all, no distance means no work. The key thing to remember about energy is that it cannot be created or destroyed, only converted. Aka, the conservation of energy. Okay, but a car, that’s moving has kinetic energy.

When the car stops, assuming the car doesn’t
smash into a wall, where does that energy go? When you apply the brakes, there’s friction
between the brakes and the wheels, causing the car to slow down, and creating heat as
a byproduct. That heat is then dissipated to the surrounding
air. And that makes the molecules in the air move
faster. And things that move have kinetic energy. So ultimately, the kinetic energy is transferred
from the car to the air. With this knowledge, we can define that Temperature
is just the average kinetic energy of atoms in a system. You see, all atoms, not just molecules in
the air, wiggle. Like this. The faster they move, the hotter things get. That is temperature. All that talk about hot stuff, I think it’s
time we talk about Thermodynamics. It tells us that jumping in lava is probably
a bad idea, but more importantly, the absolute

mess that is entropy. Literally, it tells you how much disorder
there is in a system, indicating the number of possible states a system can be in. For example, get an ice cube, no not that
one, yes that’s perfect, and put it in the sun. The sun will obliterate the ice cube and turn
it into water. Looking at the structure of ice and water,
we can see that ice is more neatly organized than water, which just kind of goes all over
the place. Also, the water could look like this, or this,
or even this, but the ice will always look a little something like this. In total, the system went from low entropy
to high entropy, meaning more disorder and more possible microstates. This trend applies everything. The whole universe is on an unstoppable path
to higher entropy. It’s also the reason why time seems to go
only forwards, or at least, that’s what we believe at this point.

Practically, entropy tells us that some forms
of energy are more useful for doing work than others. Burn some gasoline, and your car will move,
spitting out heat and gas. That heat and gas is pretty much gasoline,
just in the form of higher entropy. And as you can imagine, this stuff won’t
really make your car move, and the gas won’t spontaneously turn back into liquid gasoline. Meaning, the form of gasoline with lower entropy
is more useful for doing work. Okay, but if you put some water in the freezer,
will it not decrease in entropy? Yes, BUT the fridge is not an isolated system
and will heat up the room more than it will cool down the water, increasing the total
entropy. Wanna see some magic? Woah, what just happened? Some electrons apparently moved through some
wires and let there be light. What is going on here? Objects have a fancy something called a charge. It can be positive or negative.

Or, if you have the same amount of both, an
object is neutral. Electrons have a single negative charge. The flow of electrons is called electric current. To describe it, we use three parameters: Current,
Voltage, and Resistance. Current is the amount of electrons passing
through a wire in a given amount of time. Voltage is what pushes the electrons to move,
but simply put, it’s a difference in electric potential, so you can imagine it as a slope
that goes from high potential to low potential, where the flow of current goes downhill, and
resistance is pretty self-explanatory. This is Coulomb’s Law. Wait a minute, this is just Newton’s Law
of Gravitation in disguise! This tells us that electric charges attract
each other in a similar way masses do. Opposites want to cuddle, while like charges
literally couldn’t think of a more disgusting thing than to be with one another. These four equations explain pretty much all
of electromagnetism.

But don’t be scared just because they look
scary! I mean, yeah, they do, but it’s simpler
than it seems at first. The first one states that if there is an electric
charge, there will be an Electric field, or this big E, emerging form it. Add another and you have an electrostatic
field. These lines tell us in which direction a charged
particle would feel a force at any given point. The second one tells us the same for magnetic
fields, AND, even though electric charges are cool and can be alone, magnetic poles,
are not. They’re very lonely. There will always be a north pole together
with a south pole, and a single pole can never be alone. Okay now here’s where things get kind of
freaky. You know how electric charges only act on
other charges, and magnets only affect other magnets? Well that’s only true if they’re not moving. The third and fourth maxwell equations tell
us that a moving magnet creates an electric

field, and a moving charge or electric field
creates a magnetic field. One consequence of this is that current can
seemingly come “out of nowhere” by moving a magnet next to a conductor. The moving magnet creates and electric field,
which makes the electrons inside the conductors go crazy. That is called induction. It’s the reason why your phone charges when
you put in on the charging pad, even though it is not directly connected to a cable. In other words, electric and magnetic fields
are so tightly linked that they are the two parts of the same bigger thing. Let’s say we have a charge. Since it doesn’t move, it has a static electric
field. If we accelerate the charge, there will be
a magnetic field around it. That magnetic field interacts with the electric
field, which again changes the magnetic field, and this is a sort of chain reaction that
makes the electromagnetic field radiate outwards into space as an electromagnetic wave.

Depending on the frequency, the human eye can actually see this. It’s called light, but most of the spectrum is invisible to the human eye and is used for things such as Bluetooth, wireless charging, and confusing human apes into thinking magic is real. Hey, can we go back to the water and look at those molecules? Yeah, those, what are they made of? The molecules are made of Atoms. Atoms are made of a core and some electrons. The core is made of protons and neutrons, both of which are made of quarks. They’re strange yet charming, from up top down to the bottom. Oh yeah, there’s some more stuff, like for example the overweight brothers of the electron. All of this together makes up the standard model, which we believe to be the smallest things in the universe. At least that’s the excuse we have for not knowing what quarks are made of. Fun Fact! Depending on the number of protons in the core, you get different elements.

Depending on the number of neutrons in the
core, you get different isotopes of the same element. Most of which are a little overweight and
very unstable. So they fall apart into smaller atoms. That releases ionizing radiation. Not so fun fact: That stuff will kill you. Do not play with radioactive atoms. If you have a large group of atoms, you can
predict when half of those will have fallen apart. That’s the half-life. Depending on how unstable an isotope is, it
will survive a certain amount of time. Some don’t want to live, some really don’t
want to live, but some will live far longer than you probably will. Oh yeah, did I mention that light is like
the fastest thing in the universe? To be exact, 299,792,458 meters per second
in a vacuum. “That is pretty fast,” said everyone. Also, “Light is a wave,” said everyone.

Why? If you shoot it through two teeny tiny slits,
it creates a fancy pattern due to interference, which is just a wave thing. You see, when two waves cross, they can add
up, or cancel each other out. These gaps are the spots where they cancel
each other out, so in this case, light behaves like a wave. “Nah, screw that, everything you know is
wrong,” said Albert Einstein, probably smoking crack, after hearing about the photoelectric
effect and discovering that light comes in tiny packets called photons. I sure hope that doesn’t unravel a whole
new area of physics, haha. “Anyway,” he said, as he continued to casually
drop an absolute bomb on the entire field of physics with his theory of relativity:
He assumed the speed of light is constant because it arises from two other constants. He also assumed the laws of physics are the
same for everyone, regardless if moving or at rest.

Now think about it: If two people turn on a flashlight, but one person is standing still, while the other person is on a moving train, wouldn’t the person standing still see the other person’s light as going faster than the speed of light? The reality is: NO! It would be the same as their own flashlight. That’s impossible, except if time passes slower for that person from the perspective of this person. In other words, if the speed of light is constant, time must be relative. Also, gravity is not actually a Force, sorry Newton, but rather a consequence of masses bending spacetime. Einstein thought that the universe is a mesh of space and time, and anything with a mass bends this fabric. Also, all objects move freely on a straight line when moving through space. Gravitation is simply the result of objects following these bent lines, which appear straight to them. If you have a hard time understanding this, you can imagine two people on earth, walking

in parallel, straight lines. On a short distance, the straight lines will
never meet. Now imagine one standing on the east coast,
and one the west coast of the US. If they both walk north, eventually, they
will meet at the north pole. Because of the curvature of the earth, they
ended up at the same point even though they both walked “straight” relative to themselves. “Oh yeah, by the way, Energy and mass are
kind of the same thing,” he added, which explains why atom bombs are so frickin powerful. According to this formula, even just tiny
atoms can release a humongous amount of energy by giving up just a fraction of their mass
during fission. What is Fission? It’s the same thing Oppenheimer used to
make this thing go boom. You see, there’s two main ways to gain energy
from changing nuclei: Fission and Fusion. Fission aims to split the nucleus of an atom
into two or more smaller nuclei, which is

most often achieved by blasting the core with
neutrons. Fusion is the opposite, where you combine
two smaller nuclei to get one bigger one. The energy came from something we call a “mass
defect,” where the resulting nucleus is lighter than the starting nuclei. This “missing” mass is what was converted
to energy during Fusion. Fission and Fusion are cool, but you have
got to be careful, or you might just blow up the planet. That totally didn’t almost happen before…multiple
times. Hey, remember when Einstein said light is a
particle? He accidentally discovered a whole new field
of physics, which he thought is just a giant hoax: Quantum Mechanics. This stuff is crazy. Another German guy called Max Planck said,
“yes, Einstein, you’re right. Light does come in tiny packets. Actually, all energy comes in tiny packets,” or “Quanta.” He is the daddy of Quantum Mechanics. Wanna know where an electron is inside an
atom?

It’s here! And there! And everywhere, at the same time, actually! That’s a superposition. It’s not in one state, it’s in multiple
states at once - at least until you measure it. Then it chooses one cozy spot to be in. Schrödinger gave us an equation that gives
you a probabilistic model of where you can find it if you were to measure. You can imagine this as a cloud, and the denser
it is, the more likely it is for an electron to be there. But still, where exactly it will end up once
you measure it, is random. Speaking of observing particles, they’re
also super sensitive about their private data. Look at these two images of a flying ball:
in one, you can clearly see where the ball is, but not in which direction it’s moving,
and in the other you can see where it’s moving and approximately how fast, but not
where exactly it is at the moment.

That is essentially Heisenberg’s uncertainty
principle: You can never know both the exact position and the exact speed of a quantum
particle at the same time. Okay, let’s recap. A small thing can be
a particle and a wave at the same time, and when we try to look at them, weird stuff happens. But you know what, it gets even weirder. Think back to the double-slit experiment.
We know that a light beam acts as a bunch of waves and we get interference. But here’s the weird thing: Even if you
send individual photons, after sending enough of them and detecting where they end up, you
get interference. Like, how can that be? What did a single particle interfere with? Well, we think it interfered with itself,
because it acted as a wave and went through both slits at the same time. That’s a superposition. “Okay, well let’s just measure which slit
it goes through.”

Uh, yeah, that’s not going to happen. Once you start measuring which slit the photon goes through, it stops acting like a wave, and the interference pattern disappears, as every particle chooses just one of the slits to go through. Sounds kinda suspicious to me. Anyways, all this knowledge is going to cost you one subscribe and a thumbs up. Thank you very much, and you can decide if maybe you’d want to tip with a comment, perhaps.

ALL OF PHYSICS explained in 14 minutes

18 y/o nerd who makes silly videos on science

Wacky Science

아이작 뉴턴이 말하는 중력의 기초

아이작 뉴턴의 만유인력의 법칙은 질량이 서로 끌어당기는 원리를 설명합니다.

두 물체 사이의 중력은 역제곱 법칙에 따라 물체의 질량과 물체 사이의 거리에 따라 달라집니다.

중력은 구심력으로 작용하여 태양 주위를 도는 행성의 궤도 운동을 담당합니다.

질량과 무게를 혼동하는 경우가 많지만, 질량은 물체에 있는 물질의 양이고 무게는 물체에 작용하는 중력의 힘입니다.

에너지는 운동(운동)과 잠재력(저장)이라는 두 가지 주요 형태로 존재합니다.

일이란 거리에 걸쳐 가해지는 힘의 결과이며, 종종 에너지가 한 형태에서 다른 형태로 변환되는 것을 포함합니다.

열역학에서 엔트로피의 개념은 시스템이 있을 수 있는 가능한 상태의 수를 반영하여 시스템에서 무질서가 필연적으로 증가하는 것을 설명합니다.

이 원리는 우주에서 엔트로피의 멈출 수 없는 상승을 포함하여 모든 것에 적용됩니다.

엔트로피, 전하, 전자기학의 기초

엔트로피는 에너지 분산의 척도로, 엔트로피가 낮은 형태의 에너지가 작업에 더 유용합니다.

전류는 전압에 의해 구동되고 쿨롱의 법칙에 따라 저항에 의해 반대 방향으로 흐릅니다.

맥스웰 방정식은 움직이는 자석이 유도를 통해 전기장을 생성하는 방법을 포함하여 전기장과 자기장 사이의 관계를 설명합니다.

가시광선 스펙트럼과 원자의 본질

사람의 눈은 빛 스펙트럼의 일부분만 볼 수 있으며 나머지는 Bluetooth와 같은 기술에 사용됩니다.

원자는 쿼크로 구성된 원자핵, 전자, 양성자, 중성자로 구성되며, 양성자와 중성자의 다양한 구성에 따라 원소와 동위원소가 만들어집니다.

방사성 원자는 반감기가 있으며 이온화 방사선을 방출할 수 있습니다.

빛의 속도는 진공 상태에서 초당 299,792,458미터이며 알버트 아인슈타인이 상대성 이론에서 발견한 것처럼 파동과 광자라는 입자 모두로 작용합니다.

마음을 뒤흔드는 아인슈타인의 이론과 에너지의 본질

아인슈타인의 상대성 이론에 따르면 빛의 속도는 일정하고 시간은 상대적이며, 중력은 질량에 의해 시공간이 휘어진다고 설명합니다.

원자폭탄의 엄청난 위력에서 알 수 있듯이 질량과 에너지는 동등합니다.

핵분열과 핵융합은 질량 결함 및 질량 변환의 원리에 따라 원자핵에서 에너지를 방출하는 두 가지 과정입니다.

마음을 사로잡는 양자 중첩의 개념

양자 입자는 슈뢰딩거의 확률론적 모델에 따라 측정되기 전까지 여러 상태로 동시에 존재할 수 있습니다.

하이젠베르크의 불확정성 원리에 따르면 입자의 정확한 위치와 속도를 동시에 알 수 없습니다.

이중 슬릿 실험은 개별 광자가 서로 간섭할 수 있음을 보여줌으로써 중첩이라는 놀라운 개념을 보여줍니다.