Like I said in the last video we are about to enter the 1900s But there’s one more huge discovery that occurred at the very end of the 1800s that we really cannot ignore When it comes to the three subatomic particles which make up an atom they were each discovered years apart our understanding of the atom Definitely evolved over time and did not come all at once the first one that was proven to exist Which is also the smallest of the three is the electron the concept the electron was first theorized in 1838 by philosopher Richard Lamy He I pathi sized a quantity of electric charge which could not be subdivided and would explain certain properties of an atom It was finally in 1897 that physicist JJ Thompson proved these were in fact particles He was running experiments with cathode rays and actually ran quite a few But the main one was testing to see whether these rays would deflect due to an electric field Cathode rays or beams of electrons emitted from one side of a vacuum tube, of course This was not known back then as physicists thought this beam may in fact be a wave since the exhibited properties unique to a wave Whereas others thought the Rays were in fact particles JJ Thompson’s experiment involved exposing the beam to an electric field and he found that the beam bent towards the positive side of the field which proved without a doubt that these rays are made of negatively charged particles the Same physicist who discovered the electron proposed one of several models of the atom known as the plum pudding model in 1904 Just a couple years after his discovery where electrons made up a very small portion of the atom and were scattered throughout like plums and pudding it would not be long until This was superseded though a few years later starting in 1908 The physicist Rutherford was interested in determining the true structure of an atom which he thought was more complex than the plum pudding model predicted What he ended up doing was firing charged alpha particles through gold foil, which most of his learning chemistry as the Rutherford gold foil experiment He said that these gold atoms were like the plum pudding model The particles would go straight through and this is sort of what happened But after more testing he found that certain particles were being reflected back, which should have been Impossible this imply that there was a much stronger electrostatic force than previously predicted Meaning the atoms positive charge was very concentrated in a small volume in 1913 he published a paper declaring the existence of what he called a nucleus which contained a positive charge Then just a few years later also through experiments involving firing alpha particles this time at a nitrogen atom Rutherford found that positive charges came in single units he named this unit the proton Same charge as an electron but nearly two thousand times heavier With that we had a much better understanding of the atom However, the puzzle was not complete and it would be more than a decade until the neutron was discovered, which I’ll come back to soon now, like I said in the last video our understanding of various extremes would soon be greatly improved upon when it comes to extremes like The very fast very cold, very small, etc Strange things happen often completely counterintuitive to what we know of from the macroscopic world on a day-to-day basis We experience a range of temperatures or a range of speeds. For example But nothing remotely close to the physical limit of these parameters where these odd properties take place The first that really popped up in this century dealt with the very fast, which brings us to iron Stein’s theory of special relativity Einstein theorized something that like I said is extremely counterintuitive to what we would think about ordinary everyday objects He said that the speed of light in a vacuum is the same for all observers regardless of the motion of a light source Imagine that you’re observing someone standing on a moving train Maybe that train that’s moving 50 km/h and they throw a ball at 30 km/h if you both had radar guns What would they read? Well, the person on the train would read the ball is moving at 30 km/h, that’s how fast they threw it But the person on the ground would see 80 km/h as the Train speed would be a factor in terms of relative motion So you would not agree on the speed of the ball and this is perfectly normal. This should not be of any surprise but when it comes to light We always agree on the speed That train could be going a billion kilometres per hour If you both had a hypothetical radar gun to measure light they would both read the exact same speed the speed of light One consequence of this is time dilation which says that time takes slower for moving objects compared to those that are standing still as In clocks tick slower and people age slower when they’re moving This is what makes it possible for a twin to go on a high-speed rocket and come back younger than the other This has even been verified by putting very precise atomic clocks in orbit and having them come back slightly off from another here on earth In fact the equation for this as a denominator that approaches zero as the moving person approaches the speed of light So in theory if you got in a rocket that could go Extremely close to the speed of light and set a timer to maybe one day when you return to Earth millions billions or maybe trillions of years would have gone by depending on how fast you went and you Would have aged just one day and you would think one day I’d be gone by you May be wondering what would happen If you could exceed the speed of light but special relativity says this is a universal speed limit and therefore nothing can exceed it Now after special relativity Einstein attempted to extend this theory to a more general form Which would be known as general relativity acknowledged by some of the most beautiful physical theory currently in existence Well Einstein was working on this theory. He of course ran into constant problems one day. He accepted an invitation to speak at a university Where he would explain what he was working on he was explaining the problem at hand to the audience and one person sitting amongst the group of people was David Hilbert’s one of the greatest mathematicians of all time and while observing everything that I’m Stein is saying Hilbert thinks that he can figure out this theory better than Einstein can and from there It was a race between Hilbert and Einstein for who would be the one to complete one of the greatest theories of all time Now by pretty much anyone standards Einstein was good at math, but he was no mathematician in fact He often needed help from mathematicians to complete his theories and at this point general activity was a problem of pure Mathematics and he was up against a mathematician in the end Hilbert Einstein completed the theory at just about the same time But since so many of the foundations were started by Einstein Hilbert did not take any of the credit and this became Einstein’s theory of general relativity general relativity is something you would not learn about until likely your last year in undergrad as a physics major or maybe grad school has it’s Much more advanced than special relativity when we use Newton’s laws to analyze the motion of very large objects such as planets and stars Small errors actually occur which general relativity finally accounted for hundreds of years. Later Basically generality explains gravity and how mass actually bends space and time the orbit of mercury for example has an odd pattern compared to other planets that cannot be explained by any Theories until general relativity came along and explain these slight alterations The reason we need general relativity is that mercury is close enough to the Sun shows that the warping of space affected its orbit Whereas other plants were far enough away for Newtonian physics to give accurate predictions General activity helps us understand black holes and a predicted gravitational ways which were finally observed just a couple of years ago and one three physicists the Nobel Prize in 2017 Now that we’ve covered the very fast and the very large what happens when you take a metal to a very cold temperature Well when you do this It becomes a superconductor and in 1911 one scientist managed to cool mercury to four point one nine Kelvin or about minus 269 degrees Celsius what he observed was that the electrical resistance of the object disappeared entirely Where electrons in the metal were completely free to move and it was a superconductor Superconductors exhibit interesting property says that they expel magnetic fields and make levitation possible This is used in maglev trains that float above the ground for example Now if we achieve these at normal temperatures we can use them for a wide range of applications one being an electric power transmission A lot of electric power is lost due to friction as it’s transmitted to our homes with superconductors having no resistance We would minimize those losses and therefore reduce costs for everyone Superconductors apply to particle detectors faster electronics and high frequency electrical systems as well at the moment The applications are limited due to the needed temperature for superconducting properties to occur in 1986 the first ever high-temperature superconductor was discovered by two researchers who were awarded the Nobel Prize for their work This quote high temperature was only around 130 Kelvin or minus 135 degrees Celsius, though The highest temperature superconductor as of a few years ago is negative 70 degrees Celsius discovered in 2015 but we hope room-temperature superconductors will be here in the future and Now that we’ve gone over metals what happens when a liquid gets very cool You may think that’s a trick question as a liquid will just become a solid but take helium for example at Normal pressures once a liquid this will remain a liquid all the way down to absolute zero the cold is something can possibly get in 1937 a temperature of near absolute zero was achieved for a sample of liquefied helium and the first superfluid was served Superfluids happen when liquids get very cold And these also exhibits strange properties for one superfluids have no viscosity and this is basically a measure of a liquid resistance to deformation Which you can kind of think of as the thickness of the liquid since super fluids have none When stirred it will form a vortex that would constantly rotate imagine stirring your drink then seeing the liquid never stop turning once you stopped Also when put in a container, it will creep up the sides and along the outside forming a droplet at the bottom Now going back real quick in nineteen eleven physicist charles wilson was hiking ben Nevis the highest peak in scotland where he got to see a mountain Spectre This is an optical event that happens when sun shines from behind an observer looking out onto some peak or ridge of fog When this occurs the observers head is usually surrounded by coloured rings of light Wilson I’ve been studying meteorology and cloud formations for some time now But became motivated to then take a crack at creating clouds with a machine this then led to the invention of the cloud chamber But well, this one accomplished probably is not what you’d expect and is definitely not what Wilson had anticipated at first These cloud chambers that were filled with water vapor to form clouds of droplets actually made it very easy to see trails of ionized gas Particles these trails occur when charged particles such as alpha or beta particles like we saw earlier within radioactive decay Interact with the gas in the chamber these events are typically not detectable by the human eye But the cloud chamber would change that what was meant to be a chamber to create clouds really became a particle detector This invention went on to accelerate the study of particle physics around 30 years until it was superseded by the bubble chamber So take the study of cosmic rays as an example over 100 years ago physicists assumed radioactive rocks in the Earth’s crust Released high-energy particles iwould ionized gases in the air and give it a charge which in fact we were able to measure We were not sure about the source if this source of radioactive rocks was accurate, then the ionization should be reduced with altitude In 1910 physicist Theodore wolf took an electroscope to the top of the Eiffel Tower He found that levels of radiation were higher at the top than the base the exact opposite of what should have happened and in 1912 Victor has carried an electroscope to an altitude of 5000 300 meters in a balloon flight and again found a huge increase in the rate of ionization From this finding he concluded that this radiation was not coming from earth But instead from space The Sun being a source was ruled out when he made another balloon trip during a solar eclipse and still measured a rise in radiation therefore must be coming from somewhere else in space and this radiation came known as cosmic rays a Source of cosmic rays would be like a supernova or the explosion of a star ejecting Most of its mass these travel through space at very high speeds hit Earth’s atmosphere every single minute of every single day These are made up of mostly protons and alpha particles or the nucleus of helium But when they hit Earth’s atmosphere, they can produce a cascade of lighter particles raining down things like x-rays protons electrons and muons The muon is similar to an electron with the same negative charge but is about 200 times heavier These were discovered in 1936 during the study of cosmic radiation and were officially confirmed by using a cloud chamber experiment Muons also have an average lifetime of 2.2 microseconds Which means that there should only be so many of these that even reach the surface of the earth However, in the early 40s scientists measured over ten times more muons reaching a certain location on earth than expected This was essentially the first time that time dilation due to Einstein’s special theory of relativity was proven to be correct Time does in fact tick slower for objects moving at very fast speeds cloud chambers bubble chambers which came about in the 50s and are very similar to cloud chambers the discovery of cosmic rays and the positron which I Didn’t talk about but was discovered through the use of a cloud chamber all ended up winning these various physicists a Nobel Prize Moving on in 1927 a man named George Thompson the son of the person who discovered the electron about three decades earlier Perform an experiment that would change how we think about the electron what he did was perform the double slit experiment But instead of light he used electrons now You would think that if you shot electrons through two slits, you would see two groups of dots one behind each slit This is what would happen. If you perform this on a macro scale with like marbles, let’s say but this amazingly was not observed What he found is that same interference pattern appeared on the screen like it did with light He conclude that the particle his father discovered was not just a particle But also a wave it had properties of each and this is now known as wave particle duality Similarly we’ve also discovered that light exhibits the same dual nature And first we typically learned that light is a wave but it can also exhibit particle-like properties such as when light ejects electrons from metal This is known as the photoelectric effect, which was eventually used to create solar cells What may surprise you is the fact that Einstein is known for some very famous theories However, the one Nobel Prize he won was worth discovery of the law of the photoelectric effect He wasn’t the first to observe the photoelectric effect But did publish papers that gave a more detailed explanation of the nature of light and the photoelectric effect itself next up in 1931 experiments were done in which samples of boron or beryllium Were hit by alpha particles and what was discovered was an unusual type of radiation that was not influenced by an electric field It was assumed to be gamma radiation But both rutherford and a physicist named James Chadwick did not believe this The following year Chadwick ran some experiments to show that this radiation consisted of uncharged particles With about the same mass as a proton We now call these particles neutrons and finally the three subatomic particles of the atom had all been discovered Chadwick was awarded the Nobel Prize in 1935 for this discovery, but what’s more interesting is what happened next in? 1938 just a couple years after the discovery of the neutron something else was discovered that would revolutionize nuclear physics Chemists at Ojai began bombarding uranium atoms with neutrons as a result One thing he found in the sample was barium if we look at a periodic table barium and uranium are quite far apart So no one knew why this was happening a normal radioactive decay You may have a uranium nucleus in which an alpha particle is released Thus creating a thorium nucleus in the process do the loss of two protons and two neutrons You can see here how thorium is atomic number is just to less than uranium’s The small change is what we’re familiar with so you can see why it was odd to see barium in a sample Well, two physicists determine that in this case the nucleus the uranium atom just split in two which is why an element with a much Different atomic number was a served. This became known as nuclear fission Now when nuclear fission takes place and the nucleus splits Yes, it leaves behind two other nuclei But it can also release neutrons in the process which can then go on to split more atoms which release more neutrons and a chain reaction occurs Which releases a ton of energy this finding is what started a race to create an atomic bomb where this chain reaction would occur in 1942 the United States put full focus into creating these atomic weapons and control the nuclear fission process This became known as the Manhattan Project and in 1945 the strikes on Hiroshima and Nagasaki Showed just how powerful nuclear fission could be Nuclear physics is not all about weapons though as nuclear fission is what takes place with the nuclear reactors they talked about earlier that are what power a good percentage of the world in a way that is relatively cheap and yields very little pollution Now for a while We were not sure whether electrons protons and neutrons were elementary particles or particles that are not made up of anything else in 1964 physicists proposed that protons and neutrons were in fact made up of something else even smaller These extremely small particles became known as quarks. It was until four years later 1968 that experiments were done at the Stanford Linear Accelerator in which electrons were fired at protons electrons are much smaller in size and they observe that they bounced off the proton in such a way that could not be explained if the protons for just one ball of charge They conclude they must be made of something else And now these quarks help us understand much more about the atoms within our universe It was also assumed that the smallest charge possible was that of an electron But we now know that quarks have an even smaller charge Those quarks then add up to the charge of the respective particle. They make up Now we’ve talked about general relativity which encompasses gravity and the very large that we’ve also talked about atoms and the very small But at the moment, there’s no theory that relates the very small to the very large or a theory of everything Currently we cannot use quantum mechanics a branch of physics that deals with subatomic particles to explain gravity One of the most promising areas of research that may accomplish. This is string theory String theory hypothesizes that these tiny little strings within electrons protons quarks, etc Make up our universe and propagate through space and interact to one another string theory predicts that there are at least 10 dimensions to our universe with some theories such as bosonic string theory saying space-time is 26 dimensional and although Heim Stein’s theory of general relativity explains gravity It cannot explain what happens at the center of a black hole currently string theory may help accomplish this by explaining gravity from a quantum perspective and On the topic of black holes, it had been assumed for a while That black holes should always be increasing in size since material could only be consumed nothing in theory can escape a black hole? however In 1974 Stephen Hawking published a paper called black hole explosions in which he discussed a new union of quantum mechanics and general relativity in This he said black holes should actually release a certain type of radiation causing them to lose mass. This radiation became known as Hawking radiation The common explanation for this is that pairs of particles including both matter and antimatter Exist throughout our universe appearing and then destroying each other constantly But around a black hole occasionally one particle will be lost to the event horizon while the other escapes The particle that escapes takes some extra energy with it which is given up by the black hole and turned causing the black hole to slowly lose its mass and Lastly in the second half of the 1960’s Scientists began working on developing the standard model which would explain all the forces and matter that exists in the universe The standard model currently contains various elementary particles broken up into various classes the standard model also explains three of the four forces of nature as You can probably guess the one that it cannot currently explain is gravity But in 2012 a new particle was discovered that would be added to this model this particle explained the origin of mass of subatomic particles and was confirmed by experiments at CERN’s Large Hadron Collider This particle was coined. The Higgs boson named after Peter Higgs who predicted such a particle several decades earlier and With that we have officially gone through the entire history of physics besides maybe a few extra things here and there Yes, there’s of course plenty more that I wanted to go over but due to time I’m gonna end that video here if you enjoyed be sure to LIKE and subscribe Don’t forget to follow me on Twitter and join the major Facebook group for updates on everything and I’ll see you all in the next video

Author Since: Mar 11, 2019

  1. Electron:
    In 1874, Stoney first compute the magnitude of the “atom” of electricity and obtains 10E-10 coulomb. In 1891, Stoney suggests that the amount of charge on a univalent ion, whether positive or negative, be called the 'electron'.

  2. The involvements of other scientists in Relativity Theory are often not honored enough. Everybody associates Einstein with Special and General Relativity, while Poincare, Lorentz, Riemann, Minkowski were laying the foundations. The mathematics was already there (Differential Geometry developed by Riemann), Einstein's achievement was their application on physical reality.

  3. When i hear the accent, I was about to leave right away, but somehow the video was way too interested so I stayed and loved that i did it

  4. I was wondering if you were ever going to make videos on topics such as Digital Signal Processing or other topics you maybe found interesting in college

  5. So physicists are basically reverse engineers of nature. They take something in nature like a flower and ask how do I reverse engineer this. They find petals, stigma and receptacle. They ask how do I reverse engineer this petal. They find cells in a petal. They ask how do I reverse engineer this cell. The find molecules in the cell. They ask how do I reverse engineer this molecule. They find atoms in the molecule. They ask how do I reverse engineer this atom. They find electrons, protons and neutrons. They ask how do I reverse engineer the proton. They find quarks. They ask how do I reverse engineer the quark.

  6. I would urge anyone who values our intellectual achievements to at least run this video once. It's a sincere presentation of science as an overview. It's becoming more important as we see the flat Earth movement and the multi gender movement gather momentum. Some of these scientists have literally died in pursuit of this knowledge for the modern advances we take for granted.

  7. You telling maximum sciencetist experiements not of Indian scientist satyandranath Bose who discovered boson particle

  8. The explanation about hawking radiation is totally wrong… You can find some real explanations about it by some physicists YouTubers. Also there were some other wrong things…

  9. You should do a "The Future of [ ] " series for the different domains of science. I'd watch the heck out of that

  10. 3:50 Actually that train could not be going a billion kilometres per hour because it's more than the speed of light 😅
    It's explained here 4:46

  11. I just completed my high school, and was never shown a real picture of what a cloud chamber is like, Young's double-slit experiment, cathode-ray oscilloscope, etc.
    Thanks for this 2-video series.

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