I have learned physics I and II, linear algebra, quantum mechanics all in about two years through free lessons and lectures. I now have a job at a small particle physics lab in Colorado. You do need a degree to get certain careers, however you can do it on your own without paying to go to Stanford or MIT. It does help to buy some textbooks although.
It's always been one of my dreams to get cosmology lectures from Leonard Susskind one of the greatest minds of our time, so thank you Stanford for this great opportunity, and for supporting the spread of knowledge, its really awesome!
Susskind is an incredibly brilliant communicator, distilling the story of cosmology down to its essence. He keeps all the math the provides insight , but never gets bogged down by tedious derivations. We are very lucky he contributed his time and teaching skill to this series.
"No matter how much you believe it to be true, or how elegant and well versed its mathematical and geometrical model may be, a theory proposed in areas where no human experience is possible or attainable, will never be anything more than naturalist mythology! No better than the myths of creation adhered to by the tribesmen dancing around the fire praying to a totem in the forests of Africa." -Dr. AbulFeda Bin Massoud ua-cam.com/video/dwYKgtjGQy/v-deo.html
@@Moath1277 Spoken as an ignoramus, the likes of whom can't grasp nor explain what is discussed in this video. 😸😸😸 Go play with your fidget spinner and listen to your QAnon.
Scale factor in 1-dimensional case 9:00; Hubble constant 17:30; Homogeneity and isotropy of the universe 34:00; Geometry of space 49:00; Closed Universe 1:14:30; Life on a circle 1:22:30;
These lectures are fantastic. Not only does it give a great description of the world around us but it's also caused me to adopt "everywhere's " and "somewhere's " cuz it just sounds cool.
Until now I learnt soooooo much from this great man....I just want to say one sentence: I love Susskind for spreading his Knowledge....And of course thank you Stanford!
I was trying to get some answers about the purpose of this course in modern cosmology. Professor Susskind is a wonderful lecturer and I enjoy every course he presents. I know he's not God to know everything , so I asked/exchanged some ideas with other people and I got some Godlike answers, excathedra fully blasting my boat off the waters. I returned with humility back to the course since it seems very interesting to me and with more questions. One of them is if this course is talking about
I'am very greatfull for all this lectures... And yes older people want to be informed and learn again and again! In these lectures my past, what I learned about fysics, etc... reawakens and adjust! Wonderfull!!! Thank you L. Susskind! Jou're a great theacher! And thanks to the Stanford University to make it possible! I know that the coming winter I will turn to all this lectures again... and again! It is better and worthfull than ordinary TV!!! Thanks so much!! Learning keeps people yong!
he is the perfect physics teacher, the way he is able to convey ideas is so brilliant and easy to understand. he also sounds really wise (haha that important with a physics teacher, if they sound boring the lessons will be boring). a very clever bloke who has a great talent for teaching, very well done!
Two pieces of matter that are close to each other have less positive energy than the same two pieces a long way apart, because you have to expend energy to separate them against the gravitational force that is pulling them together. Since it takes positive energy to separate the two pieces, gravity must be using negative energy to pull them together. Thus, the gravitational field has negative energy. In a flat universe, negative energy exactly cancels the positive energy of matter.
wow...I watched this video months ago and thought this man was just an ordinary teacher (a very good one though) from a great university....but I just found out he is one of the leading intellectuals in physics!!
Not the Big Bang is an artifact (we don't know what it was) but singularities (infinities) appearing in current physical theories extrapolated to the conditions of the Big Bang. The Big Bang might be something finite, non-singular. An improved theory extrapolated to the Big Bang might not have singularities at all.
Einstein postulating the speed of light as 300,000 Km/s was one of the Einstein’s shortcomings. In actuality the speed of light was calculated before him and the results varied.What Einstein missed was the fact that the speed of light depends of the fluid of space in which it is observed. If the energy-density in the space through which the light travels is different, the speed of light is different and can be above or below the postulated limit. His big error was that he eliminated the "ether"
In most cases I think so George. It's not quite so "cold and faceless" and a class filled with students is not always so interactive. But I understand your point.
Einstein introduced the cosmological constant to explain the seemingly static universe he thought he lived in, based on limited data available to him. He withdrew this not because it is an actual mistake but because it appeared superfluous given better data becoming available, showing the universe expands. It is now re-introduced in the face of even better data, showing that the universe's expansion is accelerating. These is all data-driven, intellectually honest conclusions.
Time doesnt exist apart from energy/matter. The dynamical description or measurment of changes in energy/matter existing in space is time. That is how they are intwined, energy exists and acts in space, this activity can be measured with time. Just as energy/matter acting across space can be measured with distance. so a curve in time, would be an object taking longer to get to us because the curve in space.
"" I can learn everything I want without having to spend thousands of dollars going to college? Nice."" -- and even better - there's no exam at the end!!
Conservation of the total energy is a direct consequence of a basic symmetry called time invariance of the equation of motion. But if the space expands, this symmetry is broken, hence what we usually call energy is not conserved. Example: An isolated photon loses energy simply traveling through expanding space (it is red-shifted). Where did the energy go? Energy is not well-defined in the theory of general relativity. One can address this by including gravitational interaction energy density.
never give up man ! I am now in the university studying this stuff but I did not have chance to watch these videos when I was 13 ! Learn science and math very well till you start university !
This has been measure watching star in neighbour galaxies, but the number of detection does not acccount for all the mass that is necesary to hold the star in a galaxie toghether. So now we pretty much know that dark matters are particles that weakly interact (like neutrinos, but not moving so fast) and not MACHOS in any significant amount. Sorry if my english is not perfect, I have a hard time even writing in spanish. Hope that helps
You have to look on a scale large enough that the filaments and voids become a repetitive pattern. Looked at on a small scale a piece of cloth has obvious threads and gaps analogous to galactic filaments. Looked at on a scale of a square foot or so, it becomes a homogeneous tapestry.
Ni siquiera hablo bien el idioma, tampoco tengo una base más que un poco de educación mediocre en el tema y aún así me pareció una clase realmente interesante, resolvió muchas dudas que otros simplemente no me explicaban, creo que tener la capacidad de explicar algo tan complejo de forma tan simple es un rasgo de un buen profesor.
What is the principle of conservation of energy good for? Is that for close systems only? The way you explain it there is Energy Created as we speak. We are living in an expanding Universe, are we?
I am pressed by time and I want to take advantage of what is the newest in the field. I would not spend time on something that would be of no use to me in the near future. To round myself off, I would take courses in the history or development of the science to have a better idea of the status quo , current and future trends. I bet there is a lot going on in this field, as much as in physics that would not be "orthodox " by the current standards and "swallowed" easily by the establishment.
Most of dark matter is particles that gravitates but don't interact in any other way. Friction doesn't affect dark matter like affect our own matter, so dark matter does not condense in a small region like thecenter of a galaxie. So the gravity is not much per volume to bend the light or other electromagnetic radiation. That is "most" of dark matter, there are some jupiter-like and little black holes out there that "CAN" bend the light creating a lensing effect.
These are the standard notations in many calculus textbooks, Δx denotes the difference between x's, not exactly the same meaning as dx. And in many differential equations textbooks the dot notation is used, x^. meaning dx/dt or y^. = dy/dt esp when dealing with a system of DEs.
1:18:00 .. He is talking about how a bound/closed universe doesnt make sense with expanding universe. A bit of minutes before this point he mentioned that we can only see a small portion of the universe termed 'observable universe' and we can infer the universe is 1,000 times bigger then the observable universe.doesnt this imply the universe is closed/bound and always has an "edge/boundry" as it is expands, and only implies that because we see homogeny, and only small portion, were not at edge
I'd never heard of the Sloan Wall so I had to Google it. According to Wikipedia it is the largest known galactic filament but is still only 1/60 the size of the observable universe. You're right about his comment of "a few hundred galaxies" being misleading. I found he is often very imprecise about cosmic measurements. In one of his previous lectures he was clearer about the homogeneous scale lying between filaments and the distance at which the universe becomes too young for structure.
How did energy turn into building materials or matters? It's explained in Einstein's general theory of relativity. In fact, matter like atom is actually still in energy form. It is something to do with our consciousness that we see and feel energy as matter. Matter is just our perception of this special form of energy. Mass is given to certain particles such as neutron, proton and electron by the elusive Higgs Boson, and Higgs Boson itself is also a form of energy.
Is the redshift an indication that the galaxies are moving away from us? I thought that Halton Arp as well as Fred Hoyle have shown that the amount of redshift does not indicate necessarily a measure of distance. Anyone knows more about this controversy ?
bodhisattvateraneth Thank you much for detailed explanation. I am familiar with the Doppler effect here on Earth and I assume that it applies to the moving galaxies as well. Since in the deep space sound cannot travel we rely on photons to give us a hint as to what happens with objects in the deep space. I would assume that 2 galaxies approaching each other would see the light getting bluish since they approach. So it is reasonable rely on the red shift effect while analyzing the object in space. However, Halton Arp and Fred Hoyle came up with a catalog of “anomalous” young quasars connected(physical)to galaxies that have a considerable bigger red shift than the galaxy it is connected. You may want to search yourself. I am giving you one example but they do have many others that shutter the red shift effect as the standard indication of the status (distance and speed) of the objects in deep space. In one of Arp articles he refers to Galaxy NGC4319 (photo by David Strange) that clearly indicates a physical connection with the quasar nearby. The redshift for each of these objects are significantly different.
That maybe so, if the universe is big enough to get to that scale (I believe the sloane wall is the largest structure so far known to man), but certainly, that scale would be much much larger than what seemed to be implied by what Mr. Susskind said ("a scale bigger than a few hundred galaxies" could be a supercluster, and a single filament is composed of many superclusters)
Thanks. I was reading your response and now I see what the problem is with this Universe which started out of a minuscule ball of energy and expanded to what we have today. Actually reading Max Plank, I found one of his thoughts regarding our Universe ”Science cannot solve the ultimate mystery of nature because, in the last analysis, we ourselves are a part of the mystery we are trying to solve” so we actually are part of the set we are trying to solve. We have to be outside it to solve it.
I don't get it. In lecture 4 Prof. Susskind states right at the beginning in a Q&A session that galaxies move at speeds over c, Even in Newton law of Gravity F= G.m1.m2/d^2 The gravitational interaction must happen at superluminal speeds. If that would not happen the orbits of the planets would decay in time since the distance from Sun to Earth is taking light 8.3 minutes , so the orbits would decay and planets fall into our Sun.
@xCosmicProductionsx i am completely with you. i love anything and everything that has to do with space and the cosmos, it is just so facinating learning about how endless the universe is.
all you need is alot of will, i am 13 too and i am learning as much as i can now so it will be easier later. i am not only learning cosmology but statistical mechanics and calculus and many programming languages. So just find your will and never give up.
You're welcome Professor Susskind. Over several centuries, people have been compelled to believe in ideas that actually and factually symbolize the Universe and the celestial bodies.
@TheNickFlurry short answer...math,math,math.....there are two hard things about physics, [1] being able to visualize and understand complicated physical processes, i.e. physical intuition [2] MATH. Now, if you are good at math, the math can help with physical intuition. I would do at least a masters in math or the equivalent for starters, i.e. analysis, algebra, and topology especially for cosmology, other than that, just the regular physics coursework leading to specializing in cosmology.
Alot of you have been asking questions i feel are simply explaind bye dr. David butler in his "how far away is it" a must see on youtube for any1 with interest in cosmology
At around 38:58 minutes the comment: I don't know if Pythagoras new the 3 dimensional Pythagorean Theorem? Answer: No! The Pythagorean Theorem introduced here is a result of the introduction of the Cartesian Coordinate Sytem. The idea of this system was developed in 1637 in two writings by Descartes and independently by Pierre de Fermat, although Fermat used 3 dimensions and did not publish the discovery.
I dont mean edges to, um, space.I mean a virtual(yet very real)edge/boundary of the 3 dimensional(+time)material universe at any given time.If all energy/matter/ started together with no space,and then expanded and space was then between energy/matter/quanta,this system(called the universe)would be a certain 3-d shape at all times(if you connect the dots(galaxies).Oh and yes not perceivable because we can only perceive the observable universe,if there are not infinite galaxies,there is an edge.
I get some ambiguity from the lectures on Cosmology. I understand that Einstein postulated that speed of light is a limit of what physical objects can reach in our physical Universe. Then professor Susskind tells us that distant galaxies actually can/may travel at superluminal speeds. Even the Hubble "constant" may indicate that. I just didn't get it why in the confines of the astronomy and physics today is still considered that c is a maximum speed a material object can reach.
What does the good professor propose for the end ? Heat death...or something different ? I would love to hear his thoughts about this although i know it is a precarious position.
Thanks, this makes very much sense. Yet what I've read about the Cosmic Crystallography theory is very interesting indeed, but this approach has very much scepticism in it. Thanks for the information.
Of the big 4 (who, what, why, and how). Physicist and cosmologist only worry about the what (as in what is that?) and the how (as in how does that thing work and, back to what, what does it’s workings do to other things?). Why is utterly meaningless unless who turns out to be present AND necessary. So far the presence of a “who” has not been necessary to explain. If a “who” shows up then that who will get a Greek letter in the equations just like the other terms and we will move forward.
Page 42 1. rubber = ge-tah 1| Pounds per square inch = E = 0.001 × 10 to the power of 6 (i.e. 1,000) 2| MN/m to the power of 2 = E = 7 pounds > tons Stiffness = Young's Modulus = E 2 Unreinforced plastics 0.2 , 0.0014 mi 3 Organic molecular crystal, phtalocyanine, a blue pigment 0.2, 0.0014 mi 4 Wood (about) 2.0, 0.014 mi 5 Concrete 2.5, 0.017 mi 6 Bone 3.0, 0.021 mi 7 Magnesium metal 6.0, 0.042 mi 8 Ordinary glasses 10.0, 0.07 mi 9 Aluminium 10.5, 0.073 mi 10 Steel 30.0, 0.21 mi 11 Aluminium oxide (sapphire) 60.0, 0.42 mi 12 Diamond 170.0, 1.2 mi
someone excuse my stupidity, but in 3D space if it where isotropic and homogenous should it imply the universe is infinite? also when he derived the expression for the scale factor no attention is paid to newton's first law. i think this is what the other person was talking about when things dont add up, if we assume inertial forces the transformation works (i checked, at least galilean transformations) but it undermines the derivation in the first place also a infinite line is closed, clopen
“What if truth itself is non-all, affected by the real-impossible of an erreducible antagonism? However, does Deleuze also not follow this path?”.. ŽIZEK, Slavoj - Organs Without Bodies on Deleuze and Consequences - THe blind spot: There is a Non - LInear Geometry Topology and Events are in and out of Caos in the Horizons of it, so the consequences, are the limits (of truth) our Mind, but not in Ramanujan's Topology, so to speak.
Not really, but there would probably be a few pieces of the rubble which could be used as a shelter of sorts. Which does sort of fit, despite the statement being a mischaracterization, since even on this planet most of the place is inhospitable to us, and nearly the entire solar system would kill us. Hardly a house which is "move-in ready".
"On a scale bigger than a few hundred galaxies the sky looks the same in every direction." How is that true if we have these huge filaments of superclusters of galaxies (that theoretically lie along clumps of dark matter) with huge voids in between these filaments?
As I'm listening to this lecture, I keep thinking about one issue in my mind. The "farther" we look, the farther into past we're looking, not knowing at all what current layout of observed region is. I also firmly believe that we philosophy
though on more careful reflection if we assume in at least one place is inertial then it can be shown that all other observers also look intertial, but how does one prove that in a finite expanding grid at least one place is inertial? i'm guessing the lecturer expect the geniuses at stanford have known these implicitly?
@a3th3r two more I forgot.. those in the lecture would have had to have taken pre-requisites that would allow them to actually understand the material, and they can ask questions
I love Cosmology, maybe I want to become a Cosmologist, it is awesome that I as a 17 teen year old can study this before I learn the time when I would start study it in a University. With this you can be very prepared.
the word cosmology{cosmos(universe)+logia(study) greek }was first used from kristian wolff. ogirv101 i hope my comments were helpfull for you.sorry for my english.
Thanks for the input. I just wonder if you can give me/us some references. I want to go beyond the videos on the Utube, I want to check sources myself and to corroborate them. Do we miss something in schools? Is this info readily available?
I'm here because I thought Science channel was too dumbed down. I love how in a real physics class they tell it like it is, no crude analogies or over generalizations. It's funny how he even mentions in the beginning that this is only a basic overview. It went far deeper than anything I've seen. Now I wonder what the homework and exam problems for this course are like.... Is there anywhere I can get them?
Hey @xCosmicProductionsx You should read biographies of your role models to discover where they studied and who they studied with. Whether it's Sagan or Susskind, information is available via cyberspace about backgrounds. As a musician, I studied with legends and I just figured out (before internet) how to meet them and get the opportunities. Most people are more than happy to share experiences and give advice. Good Luck and have fun along the way...
If I got it right, superluminal speeds ARE possible in real life in our Universe, and the matter does not become infinite as stipulated by Einstein. I understand from this course that actually Einstein’s E=mc^2 may not be correct after all, and his assumption that in real life there are no speeds surpassing the speed of light 300,000 km/s
In the begining was NOTHING, then it was a fluctuation of that NOTHING that turned into SOMETHING. That SOMETHING blewup and formed a bunch of energy, which formed into gas, which formed into matter. which then formed stars, which formed galaxies, and in galaxies planets were formed.
Only two things are infinite! The Hubble distance H is the maximum finite distance we are able to observe an infinite Universe. The Big bang never happened, because instead the redshift is a consequence of the limited range of spherical in+/-out waves in the observable universe. Einstein was correct that the Universe is infinite in extent. Schrodinger, DeBroglie, and Clifford were correct that all matter is wave structures of a space medium. "Mans mind mirrors a Universe that mirrors mans mind."
I have learned physics I and II, linear algebra, quantum mechanics all in about two years through free lessons and lectures. I now have a job at a small particle physics lab in Colorado. You do need a degree to get certain careers, however you can do it on your own without paying to go to Stanford or MIT. It does help to buy some textbooks although.
Massive respect
It's always been one of my dreams to get cosmology lectures from Leonard Susskind one of the greatest minds of our time, so thank you Stanford for this great opportunity, and for supporting the spread of knowledge, its really awesome!
Susskind is an incredibly brilliant communicator, distilling the story of cosmology down to its essence. He keeps all the math the provides insight , but never gets bogged down by tedious derivations. We are very lucky he contributed his time and teaching skill to this series.
I love how this professor starts simple and builds up perfectly as the students' understanding increases! This is truly an invaluable resource.
Who came here from MIGALA? Just found this on his Philosophy playlist
Same
Me too
Same
No mames---
Yo estoy aquí por pasado de verga nomas
Just what I was looking for. A lecturer with high knowledge of cosmology and who writes neatly! Great series.
"No matter how much you believe it to be true, or how elegant and well versed its mathematical and geometrical model may be, a theory proposed in areas where no human experience is possible or attainable, will never be anything more than naturalist mythology! No better than the myths of creation adhered to by the tribesmen dancing around the fire praying to a totem in the forests of Africa."
-Dr. AbulFeda Bin Massoud
ua-cam.com/video/dwYKgtjGQy/v-deo.html
Moath Ibn Jabal wut
Cool Guy cosmology is a pseudoscience basically
@@Moath1277 ok
@@Moath1277 Spoken as an ignoramus, the likes of whom can't grasp nor explain what is discussed in this video. 😸😸😸 Go play with your fidget spinner and listen to your QAnon.
Scale factor in 1-dimensional case 9:00; Hubble constant 17:30; Homogeneity and isotropy of the universe 34:00; Geometry of space 49:00; Closed Universe 1:14:30; Life on a circle 1:22:30;
Llegué acá porque estaba en una lista de reproducción de Migala
yo igual
Igual yo, sabes como lo puedo escuchar en español o subtitulado al español?
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These are EXCELLENT lectures. Prof. Susskind obviously knows how to explain this subject. Thank you.
These lectures are fantastic. Not only does it give a great description of the world around us but it's also caused me to adopt "everywhere's " and "somewhere's " cuz it just sounds cool.
Until now I learnt soooooo much from this great man....I just want to say one sentence: I love Susskind for spreading his Knowledge....And of course thank you Stanford!
Lecture 1 : 250k views
Lecture 2 : 8k views
Great attention span there :L
7 years later and its more a 4/1 ratio, 480k views vs 128k views
I was trying to get some answers about the purpose of this course in modern cosmology.
Professor Susskind is a wonderful lecturer and I enjoy every course he presents.
I know he's not God to know everything , so I asked/exchanged some ideas with other people and I got some Godlike answers, excathedra fully blasting my boat off the waters. I returned with humility back to the course since it seems very interesting to me and with more questions. One of them is if this course is talking about
I'am very greatfull for all this lectures... And yes older people want to be informed and learn again and again! In these lectures my past, what I learned about fysics, etc... reawakens and adjust! Wonderfull!!! Thank you L. Susskind! Jou're a great theacher! And thanks to the Stanford University to make it possible! I know that the coming winter I will turn to all this lectures again... and again! It is better and worthfull than ordinary TV!!! Thanks so much!! Learning keeps people yong!
he is the perfect physics teacher, the way he is able to convey ideas is so brilliant and easy to understand. he also sounds really wise (haha that important with a physics teacher, if they sound boring the lessons will be boring). a very clever bloke who has a great talent for teaching, very well done!
Qué chingados hace en la lista de Migala?
Two pieces of matter that are close to each other have less positive energy than the same two pieces a long way apart, because you have to expend energy to separate them against the gravitational force that is pulling them together. Since it takes positive energy to separate the two pieces, gravity must be using negative energy to pull them together. Thus, the gravitational field has negative energy. In a flat universe, negative energy exactly cancels the positive energy of matter.
wow...I watched this video months ago and thought this man was just an ordinary teacher (a very good one though) from a great university....but I just found out he is one of the leading intellectuals in physics!!
Not the Big Bang is an artifact (we don't know what it was) but singularities (infinities) appearing in current physical theories extrapolated to the conditions of the Big Bang. The Big Bang might be something finite, non-singular. An improved theory extrapolated to the Big Bang might not have singularities at all.
When quarantine is too much that I unintentionally having interest with this topic
Extremely helpful, totally simple explanations
Einstein postulating the speed of light as 300,000 Km/s was one of the Einstein’s shortcomings. In actuality the speed of light was calculated before him and the results varied.What Einstein missed was the fact that the speed of light depends of the fluid of space in which it is observed. If the energy-density in the space through which the light travels is different, the speed of light is different and can be above or below the postulated limit. His big error was that he eliminated the "ether"
“Just for fun let’s suppose that we have t squared dt squared. Just for fun” Leo Susskind
great work. Thanks Stanford.
Susskind is one fantastic lecturer. He's brilliant because he knows what he's talking about and is like a conductor conducting an orchestra - his mind
Susskind and Wolfram have a hypnotic way of talking. Thanks for posting these lectures.
In most cases I think so George. It's not quite so "cold and faceless"
and a class filled with students is not always so interactive.
But I understand your point.
Einstein introduced the cosmological constant to explain the seemingly static universe he thought he lived in, based on limited data available to him. He withdrew this not because it is an actual mistake but because it appeared superfluous given better data becoming available, showing the universe expands. It is now re-introduced in the face of even better data, showing that the universe's expansion is accelerating. These is all data-driven, intellectually honest conclusions.
“Alright I’m not going to tell you the entire history of cosmology” Leo Susskind (Lecture 1)
Time doesnt exist apart from energy/matter. The dynamical description or measurment of changes in energy/matter existing in space is time. That is how they are intwined, energy exists and acts in space, this activity can be measured with time. Just as energy/matter acting across space can be measured with distance. so a curve in time, would be an object taking longer to get to us because the curve in space.
Sharing these lectures with us was very generous. Thank you Standford!
"" I can learn everything I want without having to spend thousands of dollars going to college? Nice.""
-- and even better - there's no exam at the end!!
Thanks Stanford for helping to educate the masses about our physical reality!
Conservation of the total energy is a direct consequence of a basic symmetry called time invariance of the equation of motion. But if the space expands, this symmetry is broken, hence what we usually call energy is not conserved. Example: An isolated photon loses energy simply traveling through expanding space (it is red-shifted). Where did the energy go? Energy is not well-defined in the theory of general relativity. One can address this by including gravitational interaction energy density.
never give up man ! I am now in the university studying this stuff but I did not have chance to watch these videos when I was 13 ! Learn science and math very well till you start university !
Thank you so much for making this available. This is incredible.
Comprehensive & very well taught!!
Great series - thank you very much!...
This has been measure watching star in neighbour galaxies, but the number of detection does not acccount for all the mass that is necesary to hold the star in a galaxie toghether. So now we pretty much know that dark matters are particles that weakly interact (like neutrinos, but not moving so fast) and not MACHOS in any significant amount.
Sorry if my english is not perfect, I have a hard time even writing in spanish.
Hope that helps
This teacher is great. The video is a solid argument for attending an ivy league college.
I find fascinating the way Susskind understands physics. He makes thing way too easy. It will be a pleasure talk to him about physics.
You have to look on a scale large enough that the filaments and voids become a repetitive pattern. Looked at on a small scale a piece of cloth has obvious threads and gaps analogous to galactic filaments. Looked at on a scale of a square foot or so, it becomes a homogeneous tapestry.
Ni siquiera hablo bien el idioma, tampoco tengo una base más que un poco de educación mediocre en el tema y aún así me pareció una clase realmente interesante, resolvió muchas dudas que otros simplemente no me explicaban, creo que tener la capacidad de explicar algo tan complejo de forma tan simple es un rasgo de un buen profesor.
WELCOME TO 20st century, where HIGH QUALITY EDUCATION is for free, and for everyone, you just need an internet connection.
Blesses from Brazil
I like his layout of lectures. I'd be scared as hell to take a test under this guy he's brilliant!
What is the principle of conservation of energy good for?
Is that for close systems only?
The way you explain it there is Energy Created as we speak. We are living in an expanding Universe, are we?
my question would be if space and time are always intertwined, and space is curved, how can we calculate a curve in time?
I am pressed by time and I want to take advantage of what is the newest in the field. I would not spend time on something that would be of no use to me in the near future.
To round myself off, I would take courses in the history or development of the science to have a better idea of the status quo , current and future trends. I bet there is a lot going on in this field, as much as in physics that would not be "orthodox " by the current standards and "swallowed" easily by the establishment.
Most of dark matter is particles that gravitates but don't interact in any other way. Friction doesn't affect dark matter like affect our own matter, so dark matter does not condense in a small region like thecenter of a galaxie. So the gravity is not much per volume to bend the light or other electromagnetic radiation.
That is "most" of dark matter, there are some jupiter-like and little black holes out there that "CAN" bend the light creating a lensing effect.
These are the standard notations in many calculus textbooks, Δx denotes the difference between x's, not exactly the same meaning as dx. And in many differential equations textbooks the dot notation is used, x^. meaning dx/dt or y^. = dy/dt esp when dealing with a system of DEs.
1:18:00 .. He is talking about how a bound/closed universe doesnt make sense with expanding universe. A bit of minutes before this point he mentioned that we can only see a small portion of the universe termed 'observable universe' and we can infer the universe is 1,000 times bigger then the observable universe.doesnt this imply the universe is closed/bound and always has an "edge/boundry" as it is expands, and only implies that because we see homogeny, and only small portion, were not at edge
Great explanation of Hubble parameter as well as metric of space-time.
I'd never heard of the Sloan Wall so I had to Google it. According to Wikipedia it is the largest known galactic filament but is still only 1/60 the size of the observable universe.
You're right about his comment of "a few hundred galaxies" being misleading. I found he is often very imprecise about cosmic measurements. In one of his previous lectures he was clearer about the homogeneous scale lying between filaments and the distance at which the universe becomes too young for structure.
How did energy turn into building materials or matters? It's explained in Einstein's general theory of relativity. In fact, matter like atom is actually still in energy form. It is something to do with our consciousness that we see and feel energy as matter. Matter is just our perception of this special form of energy. Mass is given to certain particles such as neutron, proton and electron by the elusive Higgs Boson, and Higgs Boson itself is also a form of energy.
Is the redshift an indication that the galaxies are moving away from us?
I thought that Halton Arp as well as Fred Hoyle have shown that the amount of redshift does not indicate necessarily a measure of distance.
Anyone knows more about this controversy ?
bodhisattvateraneth Thank you much for detailed explanation. I am familiar with the Doppler effect here on Earth and I assume that it applies to the moving galaxies as well. Since in the deep space sound cannot travel we rely on photons to give us a hint as to what happens with objects in the deep space. I would assume that 2 galaxies approaching each other would see the light getting bluish since they approach.
So it is reasonable rely on the red shift effect while analyzing the object in space. However, Halton Arp and Fred Hoyle came up with a catalog of “anomalous” young quasars connected(physical)to galaxies that have a considerable bigger red shift than the galaxy it is connected. You may want to search yourself. I am giving you one example but they do have many others that shutter the red shift effect as the standard indication of the status (distance and speed) of the objects in deep space. In one of Arp articles he refers to Galaxy NGC4319 (photo by David Strange) that clearly indicates a physical connection with the quasar nearby. The redshift for each of these objects are significantly different.
seems like he looks same from thousand year😁 such a nice man is susskind
That maybe so, if the universe is big enough to get to that scale (I believe the sloane wall is the largest structure so far known to man), but certainly, that scale would be much much larger than what seemed to be implied by what Mr. Susskind said ("a scale bigger than a few hundred galaxies" could be a supercluster, and a single filament is composed of many superclusters)
Thanks. I was reading your response and now I see what the problem is with this Universe which started out of a minuscule ball of energy and expanded to what we have today.
Actually reading Max Plank, I found one of his thoughts regarding our Universe ”Science cannot solve the ultimate mystery of nature because, in the last analysis, we ourselves are a part of the mystery we are trying to solve” so we actually are part of the set we are trying to solve. We have to be outside it to solve it.
This is like a home school :D
Thanks for everything on all your videos :D!
I don't get it.
In lecture 4 Prof. Susskind states right at the beginning in a Q&A session that galaxies move at speeds over c,
Even in Newton law of Gravity F= G.m1.m2/d^2 The gravitational interaction must happen at superluminal speeds. If that would not happen the orbits of the planets would decay in time since the distance from Sun to Earth is taking light 8.3 minutes , so the orbits would decay and planets fall into our Sun.
I'm looking forward to the lecture on curved space time already :-) This is brilliantly explained.
"this is worse that flatland; this is lineland." HAHA I LOVE THIS GUY :D
Variable *frequency*, not speed. The speed of light in a vacuum is constant, no matter how dark it is.
Yes pretty much. Usually is more interactive and you also get some handouts.
@xCosmicProductionsx i am completely with you.
i love anything and everything that has to do with space and the cosmos, it is just so facinating learning about how endless the universe is.
all you need is alot of will, i am 13 too and i am learning as much as i can now so it will be easier later. i am not only learning cosmology but statistical mechanics and calculus and many programming languages. So just find your will and never give up.
You're welcome Professor Susskind. Over several centuries, people have been compelled to believe in ideas that actually and factually symbolize the Universe and the celestial bodies.
@TheNickFlurry short answer...math,math,math.....there are two hard things about physics, [1] being able to visualize and understand complicated physical processes, i.e. physical intuition [2] MATH. Now, if you are good at math, the math can help with physical intuition. I would do at least a masters in math or the equivalent for starters,
i.e. analysis, algebra, and topology especially for cosmology, other than that, just the regular physics coursework leading to specializing in cosmology.
Alot of you have been asking questions i feel are simply explaind bye dr. David butler in his "how far away is it" a must see on youtube for any1 with interest in cosmology
At around 38:58 minutes the comment: I don't know if Pythagoras new the 3 dimensional Pythagorean Theorem? Answer: No! The Pythagorean Theorem introduced here is a result of the introduction of the Cartesian Coordinate Sytem. The idea of this system was developed in 1637 in two writings by Descartes and independently by Pierre de Fermat, although Fermat used 3 dimensions and did not publish the discovery.
¿Did they really get that grade in this 14:31 class though Avri Downey?
I dont mean edges to, um, space.I mean a virtual(yet very real)edge/boundary of the 3 dimensional(+time)material universe at any given time.If all energy/matter/ started together with no space,and then expanded and space was then between energy/matter/quanta,this system(called the universe)would be a certain 3-d shape at all times(if you connect the dots(galaxies).Oh and yes not perceivable because we can only perceive the observable universe,if there are not infinite galaxies,there is an edge.
I get some ambiguity from the lectures on Cosmology.
I understand that Einstein postulated that speed of light is a limit of what physical objects can reach in our physical Universe. Then professor Susskind tells us that distant galaxies actually can/may travel at superluminal speeds. Even the Hubble "constant" may indicate that. I just didn't get it why in the confines of the astronomy and physics today is still considered that c is a maximum speed a material object can reach.
amazin...........i learnt soooo much....he has such an interactive way of teaching......!! thnx professor
What does the good professor propose for the end ? Heat death...or something different ? I would love to hear his thoughts about this although i know it is a precarious position.
Thanks, this makes very much sense. Yet what I've read about the Cosmic Crystallography theory is very interesting indeed, but this approach has very much scepticism in it. Thanks for the information.
Of the big 4 (who, what, why, and how). Physicist and cosmologist only worry about the what (as in what is that?) and the how (as in how does that thing work and, back to what, what does it’s workings do to other things?). Why is utterly meaningless unless who turns out to be present AND necessary. So far the presence of a “who” has not been necessary to explain. If a “who” shows up then that who will get a Greek letter in the equations just like the other terms and we will move forward.
Page 42
1.
rubber = ge-tah
1| Pounds per square inch = E = 0.001 × 10 to the power of 6 (i.e. 1,000)
2| MN/m to the power of 2 = E = 7
pounds > tons
Stiffness = Young's Modulus = E
2 Unreinforced plastics 0.2 , 0.0014 mi
3 Organic molecular crystal,
phtalocyanine, a blue pigment 0.2, 0.0014 mi
4 Wood (about) 2.0, 0.014 mi
5 Concrete 2.5, 0.017 mi
6 Bone 3.0, 0.021 mi
7 Magnesium metal 6.0, 0.042 mi
8 Ordinary glasses 10.0, 0.07 mi
9 Aluminium 10.5, 0.073 mi
10 Steel 30.0, 0.21 mi
11 Aluminium oxide (sapphire) 60.0, 0.42 mi
12 Diamond 170.0, 1.2 mi
someone excuse my stupidity, but in 3D space if it where isotropic and homogenous should it imply the universe is infinite? also when he derived the expression for the scale factor no attention is paid to newton's first law. i think this is what the other person was talking about when things dont add up, if we assume inertial forces the transformation works (i checked, at least galilean transformations) but it undermines the derivation in the first place
also a infinite line is closed, clopen
Good camera operator! Susskind is brilliant as usual.
“What if truth itself is non-all, affected by the real-impossible of an erreducible antagonism? However, does Deleuze also not follow this path?”.. ŽIZEK, Slavoj - Organs Without Bodies on Deleuze and Consequences - THe blind spot: There is a Non - LInear Geometry Topology and Events are in and out of Caos in the Horizons of it, so the consequences, are the limits (of truth) our Mind, but not in Ramanujan's Topology, so to speak.
Not really, but there would probably be a few pieces of the rubble which could be used as a shelter of sorts. Which does sort of fit, despite the statement being a mischaracterization, since even on this planet most of the place is inhospitable to us, and nearly the entire solar system would kill us. Hardly a house which is "move-in ready".
Was the remark @ [ 20:21 ] so revolutionary that it was worth interrupting the lecture?
"On a scale bigger than a few hundred galaxies the sky looks the same in every direction." How is that true if we have these huge filaments of superclusters of galaxies (that theoretically lie along clumps of dark matter) with huge voids in between these filaments?
As I'm listening to this lecture, I keep thinking about one issue in my mind. The "farther" we look, the farther into past we're looking, not knowing at all what current layout of observed region is. I also firmly believe that we philosophy
is this a lecture on cosmology, or an introduction to a lecture on cosmology ?
What is the existence of universe???
though on more careful reflection if we assume in at least one place is inertial then it can be shown that all other observers also look intertial, but how does one prove that in a finite expanding grid at least one place is inertial?
i'm guessing the lecturer expect the geniuses at stanford have known these implicitly?
Well explained.
@a3th3r two more I forgot.. those in the lecture would have had to have taken pre-requisites that would allow them to actually understand the material, and they can ask questions
I love Cosmology, maybe I want to become a Cosmologist, it is awesome that I as a 17 teen year old can study this before I learn the time when I would start study it in a University. With this you can be very prepared.
so are you done with your college and studies?
You’re like almost 30 now lol
Used to be able to download these from youtube. I did this once before. What has happened to change this?
Economic inflation!
the word cosmology{cosmos(universe)+logia(study) greek }was first used from kristian wolff.
ogirv101 i hope my comments were helpfull for you.sorry for my english.
Thanks for the input. I just wonder if you can give me/us some references. I want to go beyond the videos on the Utube, I want to check sources myself and to corroborate them. Do we miss something in schools? Is this info readily available?
I'm here because I thought Science channel was too dumbed down. I love how in a real physics class they tell it like it is, no crude analogies or over generalizations. It's funny how he even mentions in the beginning that this is only a basic overview. It went far deeper than anything I've seen. Now I wonder what the homework and exam problems for this course are like.... Is there anywhere I can get them?
Hey @xCosmicProductionsx
You should read biographies of your role models to discover where they studied and who they studied with. Whether it's Sagan or Susskind, information is available via cyberspace about backgrounds. As a musician, I studied with legends and I just figured out (before internet) how to meet them and get the opportunities. Most people are more than happy to share experiences and give advice.
Good Luck and have fun along the way...
If I got it right, superluminal speeds ARE possible in real life in our Universe, and the matter does not become infinite as stipulated by Einstein.
I understand from this course that actually Einstein’s E=mc^2 may not be correct after all, and his assumption that in real life there are no speeds surpassing the speed of light 300,000 km/s
@MrSpacetimeTraveller I am glad you think so.
In the begining was NOTHING, then it was a fluctuation of that NOTHING
that turned into SOMETHING. That SOMETHING blewup and formed a bunch
of energy, which formed into gas, which formed into matter. which
then formed stars, which formed galaxies, and in galaxies planets
were formed.
There was never "nothing."
Only two things are infinite!
The Hubble distance H is the maximum finite distance we are able to observe an infinite Universe.
The Big bang never happened, because instead the redshift is a consequence of the limited range of spherical in+/-out waves in the observable universe.
Einstein was correct that the Universe is infinite in extent.
Schrodinger, DeBroglie, and Clifford were correct that all matter is wave structures of a space medium. "Mans mind mirrors a Universe that mirrors mans mind."
The money covers the certification that you understand the material, the education itself is free.