Thousands of years of physics research and discoveries has shaped the world. We live in today from technologies
we use all the time to machines and inventions that change the world all the way to our knowledge of the universe from the very
Baked to the very small without the advancement of physics. These would not exist
Although we have discovered quite a lot these discoveries happened over a long period of time some of them even by accident
So let's take a look at the thousands of years of work that went into creating the world
We live in today and some of the people who got us here
Let's start this in the seventh and sixth century BC with a man named Thales of Miletus
Whom some consider to be the father of science?
He's known for his attempts to explain phenomena through theories and hypotheses rather than mythology
For example, although this may seem like nonsense to us now one theater
He had was that all matter was made up of a single substance, and that was water
He may have missed the mark on that one
But is believed by some that he was able to predict as solar eclipse on May 28th
585 BC
Now known as the Eclipse of Daly's this eclipse actually interrupted and may have helped end a war between two local kingdoms at the time
now fast-forward to the 5th century BC when philosophers came up with a new theory that
Matters not made up of just water but a collection of elements
Water was one the others were earth air and fire
several years later
Aristotle also
Suggested a fifth element known as aether that made up celestial bodies and stars probably would not be made of the same elements down on
Earth, he definitely would have been shocked to learn that they are in fact made up of the elements found here on earth
But even though we know these classical elements to be wrong, they do align quite well with these four states of matter
We all know us
Now those are some ancient theories but where I really want to start this video is with a story
I'm sure many of you know of which begins with a gold crown and a bathtub in
The 3rd century BC live scientist engineer and mathematician Archimedes who contributed more to the world than any other scientist of ancient times
Probably his most famous contribution was made while he was taking a bath
Archimedes need to calculate the density of supposedly gold crown to determine whether some silver had been substituted by dishonest Goldsmith
He was not allowed to melt the crown to a normal shape in order to perform calculations, though
one day taking a bath
He knows the level of the water rise as he got in and he used this principle to determine the volume of the crown
Since the crown would displace his own volume in water
He was able to then calculate the density of the crown using mass over volume and concluded it was less than that of gold
Proving that silver had in fact been mixed in
later Archimedes went on to write on floating bodies where he continued his research into submerged objects and this he describes what is known as
Archimedes principle which states how the upward buoyant force exerted on a body in a fluid is equal to the weight of the fluid displaced
by the body
This principle is why you feel lighter when in water or white is very difficult to push an inflated beach ball under water
now the story of the gold crown has actually been called into question due to the accuracy needed to measure the water displacement and how
Difficult, that would be given the instruments available to Archimedes
instead a more practical technique that actually makes use of Archimedes principle would be to suspend the crown on one end of a scale and
Balance it with an equal mass of gold on the other
Then when put into water the crown would have displaced more water than the gold due to its larger volume and thus experience a higher
Buoyant force making it more apparent it was mixed with silver
Now physics is not just a foundational science
But it's also the basis of technology new physics discoveries today lead to new technologies tomorrow
And this goes way back during ancient times many Greeks were interested in the development of machines
For example Archimedes is recognized for the invention of various networks of pulleys and levers
His famous quote is give me a place to stand and I will move the earth
This of course has to do with mechanical advantage in the amplification of applied forces
Machines that make use of mechanical advantage allow us to let's say lift a car using only our own strength
One notable invention of his was the claw of Archimedes
They use mechanical advantage as a weapon to defend a portion of Syracuse's city wall during the Second Punic War
its exact design is unclear
But it worked kind of like a crane using pulleys and levers to lift enemy ships slightly out of the water
Causing them to eventually flood and sink
Nowadays simple things like bottle openers nail clippers hammers bike gears wheelbarrows and more make use of these principles
Now let's fast forward all the way to the 11th century when a physicists known as M
Nel Haytham changed the way we think about light
Although a lot of research has been done since I'll hate them is considered the father of optics
For reasons I won't go into I'll hate them was kept under house arrest for several years and during that time
He published a seven-volume collection of books known as the book of optics where he proved that light travels in a straight line
He did this through one of the first scientific experiments ever as a lot of previous theories were simply speculation
Like at this point in time that was still thought that heavier objects followed a faster rate as theorized by Aristotle
This would be proved wrong in a few hundred years though
Anyways, one experiment al-haytham performed was he cut a small hole in a wall and hung two lanterns at different locations in an adjacent room
He observed that the light
Illuminated unique spots in the opposite room and each formed a straight line with the hole and one of the lanterns
also for hundreds of years that was believed that her eyes actually emitted rays of light that would bounce off objects allowing us to see
He was the first to say that in fact light travels from objects and enters our eyes, which is now known to be correct
Now one thing he was wrong about even though he did research on them was rainbows
He assumed rainbows were an image of the Sun formed from a curved mirror due to water within clouds
It wasn't until the year 1300 that Theodoric of Freiburg use spherical
Flasks and glass globes to simulate water droplets that occurred during rainfall
He observed that light refracted onto the droplets reflected back out or they were refracted again
Although I'll Haytham did not contribute to our understanding of rainbows directly Theodoric of Freiburg relied on al-haytham spoke of optics to further
understanding of them
Today optics is applications in medicine
telescopes astronomy laser technology fiber optic cables and much more
Next up just about 2,000 years ago. The first compass was invented and although people did eventually use these for navigation
No, one truly knew how they worked for over a thousand years that was until the turn of the 17th century
It was assumed for a long time that comes as were attracted to a large magnetic island on the North Pole
That was until william gilbert came in and wrote his book where he proved. The earth was actually one giant magnet in
This book he discusses
Experiments in which he miles the earth using something called the torella or a sphere made out of a naturally magnetized material
When he passed the compass over the Torah
He saw it would always point towards the magnetic pole and behave just as it would on earth itself
The Tyrell was improved upon 300 years later by Kristian Birkeland
In order to further investigate the polar aurora and why it appeared near the magnetic poles of earth
Now William Gilbert also did work in electricity
In fact, he is credited with inventing the word electricity and many consider him the father of Electrical Engineering
One of Gilbert's inventions with the electroscope the first instrument to measure the presence of electric charge
Over 300 years later physicist Victor Hess would use the electroscope to discover something that would win him the Nobel Prize
But I'll get to that soon
Now like I said for over a thousand years it was believed that heavier objects would fall at a faster rate
This was introduced by Aristotle and it seems intuitive. But of course, we know now that this is wrong
The story that's been told is around
1590 the scientist Galileo dropped spheres of different masses from the Leaning Tower of Pisa to show that their time to reach the ground was
Independent of mass which we now know to be true
He also showed that the relationship between distance and time could be represented by this equation
Although the basic physics here proved to be accurate many historians believe that the story isn't but rather it was a thought experiment
Then Galileo did work on pendulums, but also introduced the idea of relativity
That would be greatly expanded upon by Einstein
Galileo stated that the laws of physics are the same in any system that is moving at a constant speed in a straight line
Meaning there's no such thing as absolute motion. It's all relative
If you were in a rocketship moving through space at a constant velocity
There'd be no way to determine if you were moving or actually stationary
Your brain probably is telling you that these asteroids are passing by a still observer right now
But look at it some more and you can probably convince yourself that the asteroids are still and you're moving past them
Galileo's work not only set the foundations for Einstein but also provided the framework for what Isaac Newton would go on to discover in
1687 Newton published a book called Principia
They laid out the foundations of classical mechanics and is regarded as one of the most influential scientific
publications of all time and bring Capilla Newton stated that gravity pulls masses together
The earth exerts a force on you just as you actually exert a force on the earth
He explains what this force obeys an inverse-square law
So if you get twice as far from something the gravitational force becomes four times weaker
And of course as three laws of motion were discussed here
Which one of the first things we all learn when we take a first level physics course
Newton was also heavily interested in orbiting bodies and celestial mechanics
It was believed for a long time that celestial bodies orbit in perfect circles
But Newton proved that actually an elliptical path would form as a result of the inverse square law that governed gravity
Newton also contributed to the field of optics
in fact
He coined the term spectrum in order to explain the colors that appear when white light enters a prism during his studies
He invented the first known functioning reflecting telescope or the Newtonian telescope
He did not come up with this idea
But seems to be the first to make a working one
reflecting telescopes are very simple in design and did not use a lens which offered certain advantages a
Few decades earlier Galileo design was known as a Galilean telescope. They used refraction instead of reflection
It contained two lenses and can magnify images about 30 times in size but flaws in the design caused images to be blurry or distorted
However, these flaws did not stop Galileo from being able to observe craters on the moon or various moons of Jupiter
Reflecting telescopes while not perfect did not contain some of these flaws such as unwanted refractions. Otherwise known as chromatic aberrations
Then by the 1700s more and more research was being done with electricity, but note at this time
No one knew that electricity came from charged particles
We now call electrons that was still over a hundred years away, but that would not prevent research from being done
in fact, one of the key pieces of electrical equipment in your computer phone and other electronics was first formed in
1745 when a well von Kleist was connecting metal foil to the inside surfaces of a glass jar
That was then filled with water. The goal is to charge the water by connecting it to a generator that could produce an electric charge
When kleiss then touched the foil with his hand, he experienced a very strong electric shock when that was arguably life-threatening
but what was going on was that the jar was storing electricity this became known as a Leyden jar that
Name may not be familiar to some of you but the Leyden jars also considered the first ever capacitor
Capacitors exist in all sorts of electronics nowadays and what they do is store charge
most people who be taking a basic physics class can expect to learn some basic circuit analysis with these
The applications of capacitors have a wide range store charts can be used to represent binary within a digital system
It can be used to supply large amounts of current to things like lasers and particle accelerators
They can be used as sensors. They can adjust the power and high voltage systems as needed and so on
Moving on when Isaac Newton was alive
He became a very powerful figure in the scientific community very few were willing to challenge his ideas and this continued even after his death
but he was not right about everything and the late 1700s and early 1800s Thomas Young would challenge Isaac Newton's view of optics in
1678 the scientist Christiaan Huygens actually proposed that light was a wave but Isaac Newton disregarded this and put forward his own theories
Isaac Newton viewed light as a stream of particles since he could use his laws of motion to describe them better in
The late 1700s Thomas Young defended Huygens theory and in 1804 all doubt had disappeared
We reported the results of his double slit experiment one of the most famous experiments in all of physics
He actually first observed how water waves would behave in a ripple tank
He saw that the waves were either combine or cancel each other out making some kind of interference pattern
When he performed this experiment with light and shine it through two small slits
He saw the same patterns emerge proving. That light was in fact aways
Now shifting gears in 1843 James Joule devised an experiment to measure the mechanical equivalent of heat
Back, then it seemed as though these were two very different things heat being transferred versus the physical motion of something
But he eventually showed that these were interchangeable what he did was meet a device such that you could turn a handle
Causing two weights to rise and fall
This would then turn a paddle that would stir the water within a container
When the weights fell joule noticed a rise in temperature as measured by a thermometer
After raising and lowering the weight several times
He calculated a value of about four point one four joules being equivalent to one calorie
This is the amount of energy need to raise one gram of water one degree, Kelvin
This was a little off as we now know is about 4.18 joules per calorie
Drool also showed that energy did not disappear
It was just transferred in different forms this then led to the development of the first law of thermodynamics. Just a few years later
Now something you may not know is that years earlier in?
1842 a man named Julius Robert mayor wrote a paper that discussed the concept of energy not being created nor destroyed as well as the
interchangeability of mechanical work and heat
Unfortunately for mayor he was not an actual physicist, but rather a physician so his papers were widely ignored by experts in the field
He read up on others experiments and use his own observations to come up with ideas
But not of the Train to present his findings in the proper way
This led to some disappointment when he found out years later that Joule got the credit for many of the topics
He had been an advocate for years earlier
Joule did set up his own experiments and all that
So it's not like he stole mayor's ideas
But we now give credit to Joule for these findings and he even has a unit of energy named after him and now of course
Thermodynamics has gone on to have applications in engine design refrigerators power plans and more
Then if you look up the most influential equations of all time, just about any article or video you find will include Maxwell's equations
These are the equations that tell us the relationship between electricity and magnetism these also predicted the existence of electromagnetic waves
Which propagate through a vacuum at the speed of light?
Electromagnetic waves are what encompass the signals that travel through the air when we talk in a cell phone they income as visible light
Microwaves x-rays gamma rays and so on. So basically anything dealing with optics wireless communications lasers, etc
Has its foundations rooted in Maxwell's equations
Now Maxwell's equations did predict the existence of all these types of waves you see here?
But at this time most of them really hadn't been discovered yet
We never sent a radio signal or observed x-rays, for example
But within just a few decades these would all be discovered in the late 1880s
The physicist Wilhelm Rankin was investigating vacuum tubes and external effects as current passed through them
One day while running experiment with these he noticed a florescent effect on a screen with in his lab
He deduced that a new Ray was having this effect because these were still unknown at the time
He just called these Ray's X like we do in math for unknowns
Well, he continued his investigation
He finally saw a radiographic image
which was a flickering image of his skeleton on a platinocyanide screen as
You can guess we had finally discovered was what we now call x-rays
Just a few weeks later. He used these x-rays to take a picture of his wife's hand to which she exclaimed
I have seen my own death
Only a year after this x-rays were being used in medical imaging and of course are still used today for medical and security purposes
For this discovery rongkhun won the first ever Nobel Prize in Physics in 1901. He became known as the father of diagnostic radiography and
2004 a radioactive element on the periodic table was named after him
Rankin's findings
then inspired more research into the existence of these x-rays from other sources and
Antoine Henri Becquerel was one physicist who set out to make his own discovery. He thought certain phosphorescent materials
He was working on such as uranium salts may have been emitting x-rays when exposed to sunlight. He soon discovered that this was completely wrong
What was happening was that the radiation was coming from the uranium itself without the need for sunlight?
By the way, at this point in time uranium was thought of as a harmless metal, but that would soon change
Now this phenomena observed with the uranium salts became known as becker l rays
That was until a few years later when Becker ELLs research student one of the most well-known physicists of all time
Marie Curie began investigating these rays and eventually coined the term radioactivity
although Becker L
Did not get the Rays named after him the unit for how many atomic nuclei decay no substance per second is now called a Becker
L
Marie Curie and her husband Pierre Curie are
Probably the most well known couple in all of science and along with Becker L. The three of them found that thorium was also radioactive
The Curry's additionally went on to discover two new radioactive elements polonium named after Poland where Marie Curie grew up and also radium
Then in 1903 the Curry's as well as Becker L were awarded the Nobel Prize for their work in radioactivity
Pierre Curie died just a few years later in
1906 and is best known for the discovery of the Curie point a temperature in which a magnet loses its magnetism
Marie Curie went on to be the first person to win two Nobel prizes one in physics and another in chemistry in 1911
now when the Kiryas were working on radiation research a physicist named Ernest Rutherford began working with uranium as well and
Discovered two types of radiation one that can be blocked by a thin sheet of paper, which was going alpha radiation
That consists of two protons and two neutrons
Oh, this was not known at the time and another that could pass right through the paper
But would be blocked by something like aluminum. This was named beta radiation and much more dangerous to be exposed to
The most dangerous of these three I'll discuss is known as gamma radiation and was discovered in 1900 by Paul Villard
This gamma radiation was coming off radium, which the Curry's had recently discovered
Gamma rays are not composed of subatomic particles, but instead are very high-energy electromagnetic waves
Gamma rays can only be stopped by thicker barriers made up of things like lead and iron
These are dangerous because they're extremely small wavelength and high-energy makes us that they can interact with human cells causing illness and even cancer
These are released by nuclear weapons. For example
Although this does not make this research and irradiation seem positive
radioactivity eager to apply to nuclear reactors which currently account for 14 percent of the world's power and
Radiation is used in medicine to diagnose and treat illnesses
For example radiation therapy is where we use radiation to specifically kill or slowed the growth of cancer cells
now we are about to enter the 1900s in which physics on an
Unbelievable amount of growth when making this video is honestly surprised just how much I would have to include in that century alone
You'll note our understanding of various extremes like the very large the very small the very cold and the very fast would all be
significantly improved upon in the years to come
Discoveries would lead to new inventions that changed the world and others that were more controversial
You