Electrons, the Big Bang and sporting pursuits are among the topics raised by our viewers. More physics at www.sixtysymbol... With Laurence Eaves, Ed Copeland and Philip Moriarty and Roger Bowley
Sports are clearly bad for you. I guess it is OK to do them if you enjoy them, but they will eventually cripple you. There is a whole branch of medicine called "sports medicine" just to help people recover from the effects of sports.
David Messer I completely agree. I learned a while ago not to sacrifice my body while playing any type of sports for joy. Unfortunately I learned that a bit too late since I ended up with torn ligaments in both knees and moderate arthritis now at age 30.
"Its a mistake to think of the big bang as happening at a specific place, the big bang happened everywhere, its just at the time everywhere was very close together" is a great explanation, I love the way it was phrased.
Mr.Aptronym Yeah, but where was everywhere? It seems reasonable that we could locate a point where everywhere was by taking the reverse vectors of all the galaxies.
Ted Soto I think you are missing the point. The galaxies aren't just moving apart, the space between them is actually getting larger. You could find some kind of center that things expand from. However, that's not really a place, all of the places that currently exist were just together, and the meaning of position as we know it probably does not apply. Everything it could be measured in reference to was right there. There was no larger space for it to have position in... probably.
Wladyslaw Szpilman But the balloon occupied a space albeit smaller. Unlike a balloon which could move to an entirely different position, when the universe began it occupied a space within the space it grew into. It still seems logical to me that scientists could take all the vectors of the galaxies...reverse them and that would point to the beginning point.
Ted Soto No, the issue here is that all of space, at all points is expanding. Its not an expansion from somewhere, its everything. Furthermore we do not know what, if anything, exists beyond the universe, so there is no coordinate system to use to point out a position.
Ted Soto Szpilman is correct. The balloon can move in the space of higher dimensionality in which it might be embedded. That I grant you. But if you live on the balloon, your question makes no sense. Mathematically there is not even a need for the balloon to be embedded in a space of higher dimensionality..... In summary, if the law of physics requires a higher dimensionality, then your question would make sense in that superspace. In our own space, it does not. For us, the balloon always extended in all directions without a centre....every point on the balloon is equivalent to any other one.
Schrödinger's cat is alive and well... always absconding with the prof's atoms! Damn it, I think I just revealed the location of the Fountain Of Youth. Nobody would've guessed that hopping into Schrödinger's box for a spell would grant immortality whilst faffing about.
Rafael Bezerra Dalla Costa well you assume they have SOME energy not approaching infinity, so you can be sure they are close enough together to not suddenly fly apart
I just started the video and omg look at his expression! and the mood is so serious! "where..err.. have my atoms gone? ..where.." And I dropped down here looking exactly for your comment!
I love the expression on their faces when they're talking. It's as if they're truly happy with the profession they've chosen in their lives. And they are so amused to share their fascinating knowledge.
They probably won't. Because there are theories in physics with which most of the physicists disagree but have to teach them to students because there is no alternative theories. Which is really annoying.
@@dinil5566 That's just nonsense. You don't teach what pleases you. The vast majority of topics in a physics curriculum are not controversial at all. Just nonsense.
Outside the universe has to be absolute zero because the entropy of a point outside the universe has to be zero else it would be inside some type of a different universe.
@@user-ec6kt2fg7m not really atoms are made up of fermions but there are many bosons out there like light, trillions and trillions of photons reach your retina and millions of neutrinos from the sun pass through you every second, i know it's a just but im just saying atoms actually don't make up everything
@@rufusapplebee1428 first of all if there is no multiverse then a point outside the universe is not possible. Because a point exists inside a space and a space means another universe.
This one video explains more about the "cosmic microwave background" and "the big bang" fundamentals than most of all the other videos done interviewing a single person... awesome content here!
Brady, you do have a genious aspect in your own right; in your editing. You dont go from person to person, in whole; you do it in parts. This lets us see where each dr. goes in their own mindstate, i really love this. thank you so much for your efforts Brady, it's motivating me to do great things. I hope to see you and your colleagues on the field one day.
Question: If, during the start of the Big Bang there was extremely heavy concentration of matter and energy in a small space, why did it not turn into a black hole?
Not many videos about astronomy, cosmology, or quantum mechanics impress me but the simplicity of these answers is brilliant. Great questions and wonderfully explained.
It's 2021 and this footage is from 2010. The questions in this vid are timeless, 11 years is a faint amount of time but in RU-vid time... it's massive. Great upload! Ageing respectably.
The big stretch! lol, I can think of a few that would fit that description, not just the BB. Personally, I think what you have stumbled on here is pure genius.
4:20 when i learned this in early 60's, you were told to adjust the contrast control tell the field settles down but not empty and then you still see many dots that come and go, that being the background radiation. I was eight or nine at the time...
“If the Universe is expanding slower than the speed of light why has not the light from the Big Bang already passed us?” This is the question I have been asking myself for years. Really good explanation!
Isn't it more accurate to say that electrons don't actually "orbit" a nucleus but rather exist in a standing wave of probability as to their position? The misconception of electrons flying around orbits like little planets is still being foisted on the public by the use of the Bohr model, which is horribly out of date! I see this even in so-called "science" museums, where accuracy is also ignored when the nucleus is shown as a large lump almost as big as the electron cloud instead of as a tiny blip 100,000 times smaller than this cloud. Why is this so hard to correct, I wonder?
Because the Bohr model is still incredibly useful in most circumstances excluding small atoms. The QM model gets exponentially harder to solve with more electrons where the Bohr model is analytically almost totally correct for heavy atoms; we don't scrap Newtonian mechanics just because relativistic mechanics are a better model
As I understand it a comparitive model is a grapefruit as the nucleus in the centre of a major league/national sports stadium with pea sized electrons existing in (probabilistic) shells, starting somewhere typicaly around the outer walls - Difficult to scale in a museum of science, though a footnote could be added to the models on display!
@Jack Wright: Not everyone is a capable quantum mechanics expert. Bohr's model may be out of date (is it really?), but Bohr and Planck combined are still sufficiently accurate to give some explanation on what everyday people experience in real life.
meagain2222 as in electrons spinning around?, well the electron is better modeled by probability functions than circular orbits, and even if so there has been discussion about the proton having a halflife
If the doubling rate of the universe is the same as the doubling rate of 1mm, there's really nothing "expanding" anywhere near the speed of light. The distant galaxies aren't moving through space away from us , there's just more space between us than there used to be.
Entraya Korsbakke Well, what he was saying is that it can't stand still for two reasons. A) One way a particle moves is by what we call heat, which is a particle moving due to thermal energy, which you can never fully take away (that's a classical physics issue), and B) (a quantum mechanical issue) particles have an uncertainty, so if you knew it's position very accurately, it would have a large uncertainty in momentum and therefore it would have a lot of energy (and vice versa, if you knew it had low momentum and movement, you wouldn't know where it was, and it could be practically anywhere in the unvierse and therefore wouldn't actually be still).
+Entraya Korsbakke Then you wouldn't be able to find it. It could be anywhere in the universe. It's explained in the video when they mention the Heisenberg Uncertainty Principle. You just can't know where it is when its velocity is zero. And when you know exactly where it is, its velocity could be anything. Either way when you know one thing you don't know the other.
Cinqmil yeah i know about the wobblyness of the universe, i was just curious about molecular structures, but i suppose the example was rather pointless as well as needlessly unrealistic to even provide any kind of insight or whatever
Apart from the tedious repetition that "you can't actually get to absolute zero" you seem assume that electrons are distinct particles in orbits rather than say, a wave of an integral number of wave lengths around a nucleus. At the moment we don't seem to have a relationship between temperature and wavelength (they are independent in a vacuum). Unless, the wave (electron) moves to a lower energy state (emitting energy) the electron (wave) would maintain its quantum state. Certainly the Brownian motion would cease at 0 K , and the mechanical motion of the atom would cease, but there is no reason to believe the wave would collapse. I do not recall any results that suggest that, as temperature is lowered, atomic structure changes valence or something of that sort. (Crystalline structures expand/contract somewhat but that is getting mixed up in the piezoelectric effect. Diamond has a coefficient of thermal expansion of 1E-6 / K but is that vibrations in the lattice or size of the atoms? I have not heard any claim that the carbon atoms shrink as the temperature is lowered). Additionally, there is no apparent dependence of Maxwell-Faraday equations on temperature (what is temperature in an absolute void?). Similarly, the photo-electron effect depends on the frequency of radiation and temperature. And of course, temperature is really just a measurement of the kinetic energy of the atom (molecule). Considering just a single atom, the kinetic energy is related to the inertial measurement frame. If we change the reference frame to match the atom, the absolute temperature is exactly zero. No energy is lost, the electron (wave) still continues about the nucleus as usual. This "trick" won't work with a collection of atoms since they are going all different directions. But, individually, each atom maintains its own atomic structure when the collection is cooled to 0K since it doesn't "know" what the other atoms are doing. (Unless you can show some kind of thermal entanglement phenomena!) To the editors at sixty symbols: you really needn't be so condescending. The You-tube viewers might not be as unlearned as you think.
What you are looking for is kinectic energy: K=mc^2(gamma-1) gamma=1/(sqrt(1 - (v^2/c^2)) Although this formula only applies to velocities greater than 0,1c because if aplied to cosmic matter(objects moving in space) because of gamma - the relativistic constant and gamma is used the see the correlation between time observed by us because objects faster than 0,1c suffer time contraction and its also used calculate time,energy in a moving referencial from a static referencial(e.g. The earth)
I am not a scientist but an avid layman. Are these ideas, movement at absolute zero and Heisenberg uncertainty, the basis of the Bose-Einstein condensate? Since nothing can ever stop an electron other than its annihilation, some other property of electrons is exhibited very near absolute zero? They appear to be cloud-like because there is only a probability and nothing more that a given electron is in a given place at a given time? Do I have at least a not totally embarrassing layman's grasp of it?
I would also add that the electrons are forced to keep moving by the Pauli exclusion principle. Even at absolute zero, they must obey Pauli-Dirac statistics, so that two electrons could fall down to the lowest momentum state, but the rest would have to occupy the higher states. The fastest electrons are on the surface of something called the Fermi sphere, which is a sphere in momentum space, and these electrons, even at absolute zero, would be moving at the Fermi velocity, which depends upon the physical properties of the material in question, but it's around 1% the speed of light.
Heisenberg uncertainty principle is like the problem of determining position and velocity. If you want to determine velocity, it has to be over a range of positions. If you want to accurately determine position, you can only use a velocity of 0.
There should be a Brady Haran convention, which would get people featured in Sixty Symbols, Numberphile, Nottingham Science etc together to deliver lectures to visitors and meet and greet them and such. That'd be great. :)
Yes they do keep moving. Temperature is a quality of the whole atom. It's the amount of energy/vibration it has. So atoms vibrate/move around more, the more energy they have. If the energy is taken away, the atom slows down and eventualy stops at absolute zero, but the subatomic particles move the same as they did before. Temperature is different from the quantum mechanics strong force and the shape of the wave-function determining kinetic energy, that governs the motion of electrons. At least that's how I understand it.
For the simplest and clearest explanation, read Feynman's book 6 easy pieces: They have to move, otherwise it will violate the uncertainty principle. You can't know an object's speed AND location.
Momentum is related to energy. Photons have momentum given by planck's constant divided by the photon's wavelength, or the photon's energy divided by its speed
70 (km/s)/Mpc, it was first calculated by the Hubble telescope by measuring something called the redshift. The value is ~2.27e-18 hertz which has been calculating by how much the light spectrum of distant stars is being shifted towards the infra-red end of the spectrum.
To put it in simple terms... It is analogous to if there was a straight track with an infinite number of lightbulbs that incrementally get farther and father from you. If those lightbulbs were to flash all that the same time (forgetting that the light would dissipate off other atoms, just assume the light does not dissipate), you would ALWAYS see light because when the photons of one lightbulb passed, the next one would be where you are. That is a simplified version of why.
how is it that it can have no mass. by no mass, do they mean very, very small mass? I can't imagine something having no mass. Everything has to have some mass.
i can see from the E=mc2 equation that mass can approach zero (i.e. become very small) and energy (like that of a photon) can still exist. But if m is 0, then the right hand side of the equation (mc2) is zero. Which means there is 0 energy E. Therefore just from my layman's perspective looking at the equation, I am concluding there is no such thing as no mass. When the words no mass is used, I presume what is meant is very, very small mass.
You are misinterpreting reality. Photons have no mass. That's why it's described by small "c" in the equation. It's the constant of light in a vacuum. If you want to disprove this I suggest you write about it in and submit it to peer review. If you want to learn about it, you will need to read about it yourself. But you are arguing against reality itself. Learning about relativity will teach you what you want to know.
***** mass is now defined as the interaction with the Higgs Field photons and gluons have no mass, they do have energy however, and therefore have relativistic mass.
I know he is joking about physical exercise being "bad" for you, but As a doctor of pharmacy myself, I can attest that there are literally THOUSANDS upon THOUSANDS of studies linking physical exercise with not only a longer & healthier physical life but a better quality of life, both physically & mentally.
The guy at 5:00 is always giving these ridiculously complete, complex answers right off the top of his head. He seems incredibly smart. A lot of the other guys just blurt out things and make a joke.
Wait a minute. If electrons can never be stopped, not even at absolute zero, then that's means that they are always moving. Always. So electrons have been buzzing around their host nuclei for over 13 BILLION years. How is that possible? Wouldn't they run out of energy? Unless I'm missing something here, it seems as if electrons have infinite energy.
itsMinuteMaid Quantum physics is insanely hard to explain in words, but basically, an electron's position in space cannot be precisely known, so it exists as a cloud of possibility over a nucleus. Changing its energy changes how far above the nucleus the electron is, but it doesn't change whether or not it is actually in motion. It doesn't make any sense, but that's how quantum physics do.
itsMinuteMaid a particle moving at constant velocity retains its energy. A simple classical equation is KE=1/2mv^2. Kinetic energy = a half of the mass multiplied by the velocity squared. For it to lose energy it would have to hit something and transfer some of its energy to another particle. Your actually confused about the same thing as ancient Greek philosophers. Our world is dominated by friction so everything always slows down. Of course friction is the particle colliding with the air molecules or something else.
itsMinuteMaid " If electrons can never be stopped, not even at absolute zero, then that's means that they are always moving. Always." Yes! "Wouldn't they run out of energy?" No - the question you are asking was asked by physicists at the start of the 20th century - and in the struggle to understand how electrons can orbit the nucleus *forever* and never lose *any* energy Quantum Mechanics was born. You should read about it - its fascinating. "it seems as if electrons have infinite energy" No, they have a definite fixed amount of energy ( a Quantum - a definite amount.) and they lose zero energy if they stay in a stable orbit. Zero energy lost per second is zero energy lost per day, zero energy lost per year and zero energy per Billion years. They loose no energy *at all* orbiting the nucleus in a stable orbit. That is why they can do it forever. "If an electron loses 0 energy per year, how much will it lose in 100,000,000 Billion years ? Answer : 0 " It is counter - intuitive but so is much of fundamental reality. 8-)
Бојан Драшко en.wikipedia.org/wiki/Charge_carrier en.wikipedia.org/wiki/Valence_and_conduction_bands en.wikipedia.org/wiki/Intrinsic_semiconductor en.wikipedia.org/wiki/Extrinsic_semiconductor en.wikipedia.org/wiki/P%E2%80%93n_junction Read those in order and you have yourself a crash course in how P-N junctions function. Pretty neat stuff...
here's an easier way to asnwer this: the speed of electrons around the nucleus according to the classic Bohr model does not depend on temperature, it only depends on the electric potential created by the nucleus and the masses of the two.
This kinetic energy of the atoms (though not sure if this is the right term in this context) is manifested in the macro scale as heat. So we have been harnessing this energy for tens of thousands of years, ever since we got control of fire. Unfortunately it's not free energy (excepting solar collectors) because energy has to be provided to increase/maintain the energy levels of the atoms. Re. free energy. Remember the 1st Law of Thermodynamics which simply put states that any energy put into something must be taken out of something else.
Moses Bullrush Electrons don't actually orbit around the nucleus of an atom, it's much more difficult to explain how they are actually existing in relation to the atomic nucleus - but to answer your specific question of where the energy comes from, the motions of electrons are intrinsic quantum mechanical properties, nothing is "pushing" them around so to speak, instead the electron is designed by nature to jiggle around and pop in and out of different positions around the nucleus, it just does what it does, it's not a matter of needing a source of energy it's just a quantum phenomenon.
Morris The Cat That's not exactly true. Yes, there are particles being created out of nothing all the time but always two at once which behave exactly opposite from one another. Because they are opposites they effectively cancel out. Like matter and anti-matter. Sometimes particles pop into existence at the very edge of a black hole which results in one particle falling into the black hole and the other shooting away into the universe. This phenomenon is called the Hawkings Radiation but it's not proven yet. Still, there is only so much energy in the universe and it can never increase nor decrease. However, entropy is always increasing and at some point in the future, which is estimated at about a googol (10^100) years, all the energy will be spread out evenly. This scenario is called the Heat Death of the universe.
Why do they need to keep asserting "you can't reach absolute zero". It's not as if physics students are not familiar with 'ideal' situations while solving problems in school. We have frictionless surfaces, air that provides no resistance, gases that behave ideally, fluids that have no viscosity, harmonic motions with no energy loss, *perfect* resistors, capacitors and inductors, wires with zero resistance. All these situations are impossible in real life but our teacher didn't keep saying they can't exist over and over. I'm pretty sure almost everyone knows that the question is purely hypothetical. I'm NOT annoyed. I'm just wondering whether there is actually some reason why they need to repeat it.
Even theoretically absolute zero is prohibited by the laws of physics, the same way that faster than light travel is impossible. The other situations you listed are not theoretically prohibited (the opposite in fact), they're just complicated by other real world factors.
some funny scientist on RU-vid said "food is not quantized! no one requires a set amount of food!" he means that theirs a definite line between the quantum and molecular worlds. I've been thinking about it for half a year and there's no equation I've heard yet, but there is a line between quantum and molecules. also, protons are expected to disintegrate in about 90 billion years which is 40 billion after the big rip which will happen sometime before the big crunch. rip actually does dissolves everything we've ever known, similar but very different to proton decay which might be different per particle type.
This refers to a different zero then the one our temperature uses. This one refers to "Absolute zero is the coldest possible temperature. More formally, it is the temperature at which entropy reaches its minimum value"
ok, i have a question about the cmb, if it was at a high frequency when it was emmited, and due to redshift has moved into the microwave part of the spectrum, so where did the energy go? because these microwave photons have less energy than the high frequency ones that were emmited.
The real question is whether superconductivity---lossless energetic electron large motion---diminishes as temperature drops to absolute zero: Believably it does not: the 'random thermal' motion of atomic nuclei does not affect that... However, as you walk through the room and approach the test object, move it around the lab to another test, its bottommost energy levels change minutely and absolute zero is 'lost'... the cosmic microwave background does not alter absolute zero, itself, but does indicate the cosmic 'stretching' which does...
Its best explained at 1:17, but basically its the same thing as reaching the speed of light, either you would need to be massless (i.e. light) or require an infinite amount of energy pushing you to travel at the speed of light. Similarly, if you wanted to bring something to absolute zero, you need an infinite amount of energy to work with. Another good example is limits, like those of the graph f(x)=1/x. As x approaches infinity, f(x) approaches 0 but never touches 0.
Perhaps vacuum energy is what powers electrons and photons. Their motion is completely random however they move at a very regular speed in an arbitrary direction and in this way behave exactly as though they were part of one big wave. All a wave is, is particles moving at random. The larger the particle the less it's motion is disturbed by this vacuum energy and thus you get mass.
I would also say that electrons are not spinning around the atom but are in a cloud of probability. They “change” position every time you measure it but in reality the cloud and so the electron is always in the same “position”
Having an uncertainty in momentum doesn't mean a fluctuation, it just means you don't know the direction it's going. Motion is relative, so an electron in vacuum is technically at absolute zero from its own frame of reference. As the universe increases its expansion and the cosmological event horizon shrinks, all particles will eventually be causally disconnected, thus becoming absolute zero.
3:46 “Space and time are created from the Big Bang” The basic element required for occurrence, for a change anywhere in the emptiness of space is Time. For the Big Bang to happen, or for anything at all to happen, time is needed.
Not a physicist but I gotta say, this feels like a paradox in a question. Atoms having mass means they’re sort of representative of a certain amount of energy. You cant have atoms without energy because they sort of are energy. Absolute zero means a state of absolutely no energy at all. So having atoms in an environment of absolute zero to me sounds like a paradox.
