When Conservation of Energy FAILS! (Noether's Theorem)
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- Опубліковано 7 чер 2024
- Go to audible.com/thescienceasylum or text 'thescienceasylum' to 500 500 to get started today. Is energy always conserved? Well, Noether's theorem in combination with Lagrangian mechanics and general relativity tells us that isn't true in general.
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VIDEO ANNOTATIONS/CARDS
Lagrangian Mechanics:
• Lagrangian Mechanics: ...
What the HECK is Energy?
• What the HECK is Energy?
Noether's Theorem Explained:
• Noether's Theorem Expl...
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RELATED UA-cam VIDEOS
PBS Space Time on Energy Conservation:
• What is Energy?
• Noether's Theorem and ...
Physics Girl on Energy Conservation:
• Is energy always conse...
Minute Physics on Energy Conservation:
• A Simple Proof of Cons...
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OTHER SOURCES
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Emmy Noether:
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TIME CODES
00:00 Intro
00:21 Conserved Quantities
01:14 Energy Transformation
01:58 Conservation of Energy
02:27 Noether's Theorem
03:06 Time Translation Invariance
03:39 Principle of Stationary Action
04:20 The Spacetime Lagrangian
05:07 Cosmic Microwave Background
05:46 Dark Energy
06:37 Summary
06:57 Outro
07:21 Sponsor Message
08:19 Featured Comments
Really helpful as I insist on only learning through squirrel motion examples.
I saw your "Undergraduate vs Graduate Physics" video a while back and laughed so hard I got hiccups.
A wild Dotson appears 😎😎
@@ScienceAsylum "what exactly _is_ spin?" got me.
@@ScienceAsylum you and Andrew should definitely do a collab(any topic), it will be a must watch for me!!
Hey Andrew
"Potential energy is stored in the balls."
-Particle Physicists
😂😂😂😂😂
😂😂😂
Masterful! 🤣🤣🤷🏽♂️😎
You mean the tustecuts😂😂😂
You know what i mean
You are the ONLY person I have found on the Internet who CORRECTLY explains Conservation of Energy and Wave Function Collapse. Kudos to you.
you conserve energy by turning off the lights, and waves collapse on the beach. gosh its not like this stuff is difficult!
@@Blox117 thanks lord blox for this knowledge.
@@Blox117 my lord, can you explain me that where all the energy which is present in our universe came from? Maybe big bang but where did big bang get it from?
@@Warlord_Megatron What a strange question to ask someone who just made a joke.
Is that normal for you? You hear a joke and then ask the comedian a question nobody has been able to answer yet?
@@Warlord_Megatron Thats the thing: its always been here
the only thing that change is its location and distribution
Emmy Noether is quite likely the most intelligent person of the 20th century. Brutally intelligent.. Physics had a crisis that no one could solve so they asked her for help.. She proceeded to formulate her theorem which links continuous symmetries to conservation laws. Her field is abstract mathematics (abstract algebra to be precise) and was described as reasoning about operators in a completely different way than her peers. She was a professor in the most prestigious math college in germany but because women weren't allowed to teach at college back then she had to officially work under the name of a collegue and without pay...
For years the most brilliant mathematician was teaching students at the top faculty for mathematics and she did it for free
Her contributions were revolutionary.
Thanks for the info :)
Noether's Theorem to physicists is like water to a fish. It's just everywhere.
Conservation of energy does not work only with time dilation, and works perfectly within absolute time. And so are all Newton's laws, momentum conservation, and even particles entanglement. Check "Is Energy Conserved in Variable Time? All real systems (macro and micro) experience time dilation."
Ooooohh, so that's why squirrels in my park explode...
Indeed, so there might be truth in that old wives tale that Lemmings explode too... 🤔
@@_Arminius I used to have the old Lemmings game. I like puzzle solving games.
This is hilarious thank you. And I totally pictured lemmings too lol I miss that game they should make a new phone version. A good one
Nah, there's just a shortage of whale carcasses to explode and _they_ need to stay in practice. 💥
@@ScienceAsylum "UUEEH!"
* *SPLAT!*
03:05 I love how it shows the earth burning a 100 years from now.
Weird how this is still widely regarded as an exact law of physics, altrough it is known to not hold for a long time. Another one is the 2nd law of thermodynamics: there's an extremely small, but non-zero probability for entropy to decrease in an isolated system.
Most people don't need to know about this long-time exception, so it's often just easier to lie about it to emphasize the importance of the principle. A lot of the time, successful teaching is knowing exactly how much to lie.
Let's not forget how quantum theory shakes it left and right as well.
That said, for most applications treating energy anything other than conserved is very pedantic and totally unhelpful. I'm sure NASA hasn't even thought about it when sending space probes to the wastelands of the outer solar system.
That said, while Noether's Theorem makes a big dent into the holy priciple of the concervation of energy, the concervation of energy for a long time indeed has been a holy foundation of physics like so many other asumptions. Newtonian physics was improved by the relativity. Atoms once were considered indivisible, then electrons and the nucleus were discovered, it was discovered that the nucleus is made from two types of particles which eventually again were discovered to be composed from yet smaller bits and pieces. Like so many principles one should keep in mind that they're helpful shorthands that hold up when looking at things from a certain distance but fail close scrutiny.
@@ralfbaechle If I remember correctly then in the vacuum of space or where (I don't remember exactly if it's some dimension or what but obviously in this universe) energy is actually being created but it's of lowest potential so that's why we can't extract it. The zero point energy if I recall correctly.
Yes, in an isolated system. Doesn't the second law state that net entropy always increases?
@@suryanarayan2032 it says "tends" to increase. I think Brownian motion or the Brownian Ratchet shows it's not really a law but just an observation of the most common case.
You have a gift for turning complex physics math salad into intuitive concepts with these animations; like the energy bar changing over time to show where the energy is but that the overall amount of energy you're looking at is still the same.
Somebody said "We imagine that the universe is strange. But, in reality the universe is stranger than we can imagine." The universe is under no obligation to make sense to us.
It s like everytime the universe evolves and new laws exist wtf
I bet there s going to be a new form of physics that says everything in relativity and quantum mechanics is partially false in the certain extreme circumstances
@@mrhatman675 you are already correct
@@mrhatman675 You are right.
@@namidawhamida5958 what happened?
PETA called, they're asking about your non-conservation of squirrels
But seriously, great episode
Maybe it is just a really defective clone, and not a squirrel at all.
@@BainesMkII #defectiveclonelivesmatter
@@jamestheotherone742 hahaha
@@jamestheotherone742 lmao
@@Warlord_Megatron please watch gary yourofsky's speech on veganism on UA-cam please and end animal cruelty also check out earthling Ed, Dr neil Barnard, mic the vegan , Dr michel greger and joey carbstrong for more info and insight 😇💚
I died at “conservation of energy is sometimes violated”
This ist the only channel in YT that I watched every single episode, best science channel!
I lose my conservation of energy every morning when I wake up.
Relatable!
😂
Coffeeeeeeeeeeee!!!!!!!!!
Dark energy sucks your energy to expand the universe 😁
Coffee energy is transformed into brain energy.
wow the thumbnail was genious! I always loved your conservation of energy running gag, so this ep feels like a conclusion to a plot line that you have been setting for some years.
Also its good to see some love for Noether, she was a true maths and psychics badass
*physics
Wow, amazing video Nick! I didn't know that! Super interesting :)
Thanks Mithuna!
Really love your channel. Especially the fact that you try to go a bit beyond what usual popularization physics channels do while staying simple ! Keep going through "untold" subjects :)
I really like seeing videos that call back on previous videos to allow for a complex subject to effectively be communicated in a quick video.
I never thought about those two exceptions changing the actual quantity of energy in the universe, but that seems obvious now. Thank you for pointing that out! Your videos are a joy to watch as well as informative.
Love finding a new science channel to binge watch - amazing stuff, thank you!
Not a Physics student, you explain things so clearly & in such a digestible way, I enjoy watching it. even though I might not use that in a professional capacity. Great to find your channel. Good Day.
I love it when he says "Conservation of energy shall not be violated", but this video made me think, like crazy, hope you keep this up.
finally thank you for clearing this up I have been wondering about this for a while
You're very welcome :-)
I just wanted to say thank you. 😊 Because every time I watch your videos I fall in love with Physics, Mathematics and this Universe..... Wonderful and Informative videos. Keep up this great work.
That's wonderful!
Been a fan for years, glad to see the channel is steadily growing, but it's a fricken crime this isn't the number one science channel on youtube.
You really make it understandable. An ethical channel!
I just want to say that you're on the same level to me as "physics videos by eugene khutoryansky". Both you and Eugene do a fantastic job at teaching difficult subjects and making abstract AF concepts actually "click" and finally make sense. I've never had as many "eureka I finally understand this" moments from the same creator as I've had from watching your videos.
If Richard Feynman was alive and had a UA-cam account, I'm sure that he would have been a great fan of your content.
Keep up the great work. The world needs more videos like yours.
Thanks! 🤓 It's always nice to hear that my work helps people understand.
I agree.
I'm so glad I found this channel, already subscribed!!
Yet again elegantly explained. Thanks. Best science vids on YT.
you are just awesome sir!!! before seeing this video i thought that there wouldn't be any source of 'noether's theorem and conservation of energy in large scale' that suits me, but this video gave a great outlook on the concept. I think u must release a book on some concepts which are not familiar and not explained well or which are of inadequate of sources that suits people like us
He wrote a physics book. Check it out.
Your electrodynamics series helps a lot, more of that please!!
I'm getting back to it soon. I needed a break. The channel was turning into "the electrodynamics channel" and I didn't like it.
Cool video! Awaiting more solid videos on Generalizations and co-ordinate transformations.
Great video, as always! Man you deserve more subscribers! Ly
I've thought a couple days ago about that, it seemed unreasonable that the universe is expanding but the amount of energy stays the same.
by the way, love this channel youre making science understandable for everyone.
One of the best physics channels. Up there with PBS Space-time
@@Neoprototype That channel might just be aimed for just a bit more knowledgeable audience. Doesn't make it a bad channel.
patrick henry Why? It is not crap.
@@Neoprototype I'm not sure you've ever even watched PBS Space Time, because Matt goes into great detail explaining the concepts (sometimes too much). Just because it may not be a style that you enjoy doesn't mean he's not explaining.
@@TheChrasse Sometimes you can just hang on with the tip of your fingernails, other episodes of PBS spacetime are for 5'th year theoretical physicists that read up on obscure 1800' theories in their sparetime.
At least PBS Space Time doesn't think conservation of energy can be violated.
So generous a patron supporting the obviously worthy Asylum. I hope to follow the example post-university!
In the beggining God said Let there be light, then light redshifted
My God that was a nerdy jokes
What do you do with your life?
Excellent video and well worth multiple viewings for students.
awesome vid as usual! I found your channel last week and binge watched all your videos! I have a request - i'd like to see more quantum mechanics/theory videos. I've been wondering about quantum particles and how QFT relates to the larger macro world. thx!
Working on it :-)
I honestly don't how your channel only has 152k subs, you deserve millions, I guess you just need a video to go viral to get the exposure. good luck
The majority of people(like 85%) is not the clever one. Everyone subscribe to what they understand or what´s trendy on main stream media... Good luck with the elections!
A few days ago the question of where the energy of the CMB goes as it gets redshifted by expanding space has popped into my mind, so thank you for answering that!
YDT is the man! (or lady, not sure which😊)
And as usual great video. This is one of the best channels by far. Not to mention important. imo
I literally found this channel this week, and have binge watched the whole thing. I think I may have gone a little crazy 🤪 (but that's OK 😆)
I'm glad you're enjoying my work 🤪
Complex concepts with if not simple, great explanations!
This channel deserves many more subscribers
I love your videos you are amazing at explaining things I wish you could do more of them
Me too.
I know what is NOT conserved...my previous physics knowledge...AGAIN 😫😬
😂😂😂😂😂
If you could make some videos to explain more about those equations I would like that so much. I can't find anywhere else where the explanation is as good as you do.
Aside from your wacky delivery, you have got to be the best teacher I've ever run across. Great presentations. Thank you.
What do you mean aside from..? His wacky delivery is a great form of humor and engagement for personalities like mine... It's like a teenage genius enjoying a state of mania that grew up further to be relatively calm and disciplined.
@@ephemeralvapor8064 That's the crux of it. It does not suit my personality. I'm just too serious
Just as you stated at least twice, the variations on our everyday life are so tiny that we might as well just ignore them. Which is good, because so many of my required calculations during my studies depended on the principle of energy being conserved. Otherwise, I probably would not have got my degree.
Very interesting, I was just wondering and I couldn't how energy is always conservating if we have this issue of dark energy and CMB, Thank you, You explained it in a very fun and understandable way.
Happy to help 🤓
@@ScienceAsylum love your videos. They fun and informative at the same time❤️
I asked a question about this topic online and I was quite surprised at how many physics literate people didn't know about this exception to energy conservation. I'm not surprised the average person doesn't know about it, but I thought most physicists would. On the bright side, I've already linked to this video twice in response to people who didn't know about. Hopefully you'll get some new subscribers.
But I didn't get that where did universe get it's energy from? From the big bang? But then where did big bang get the energy from?
@@Warlord_Megatron We don't know.
Oh Yeaah Finally it makes sense!! Great Video!
5:14 That sound effect cracks me up every time XD
I didn't even realize it wasn't part of the background music track, since it's right in key and all.
I don't get it.
OMG! He made an entire video about it! ahahaha so funny! It seems like whenever we get closer to fully understand something the universe somehow blow it away. xD
Your squirrel motion examples help me understand so much better.
Underrated channel for sure...
"Conservation of energy shell not be violated!" Gets funnier every time.😆
This video was a long time due. Every time you uttered your conservation of energy mantra I screamed Noether's theorem internally.
This is actually the first good explanation for this on youtube
Finally! You did a Noether Theorem video!
I told this to my friend. He may think I am crazy now.
i guess I'm in the right place :)
Dont worry. Your not alone. Actually I cannot believe it. If the first rule of thermodynamics fails on the cosmic level then something is wrong.
@The Science Asylum What makes you so sure that the energy gain from dark energy is not compensated by an energy loss in other (potentially unknown) quantum fields?
The energy in those hypothetical fields would still count towards the total energy density in the Friedman equations that describe the expansion of space. So AFAIU then there would be no accelerating expansion we could observe, and thus no need to postulate dark energy in the first place.
Plus, y'know, the complete lack of evidence or theoretical necessity for any such field. :^)
If it's balanced by an energy loss that would be gravitational potential energy which is a negative number but I'm not smart enough to know if this even comes close to balancing out
Dark Energy makes up 70% of all known energy/mass in the observable universe.
That quantum field you postulate would probably already be discovered by now.
This was just awesome
Totally blew my mind
Great video as always. I would like to mention another situation. During Meson exchange inside atomic nucleus conservation of energy is violated all the time. Heisenberg's uncertainty principle ∆E∆t>h/(4π) allows it. In this case ∆E∆t
"conservation of energy shall not be violated" I want that on a t-shirt!
Good idea!
@@ScienceAsylum , Yes but with him doing that power pose!
Question: if the CMB is shifted to lower energy due to the expansion of the universe - isn't that energy just spread out over more space making the sum of the energy the same across the universe, but less only locally?
The total across the universe is _also_ less.
Nicely explained! Thanks Nick.
Yo, YDT, thanks bud! :D You make up for poor buggers like me who can't contribute anywhere NEAR that much to keeping this awesome content coming.
I love how your clone bows his head in shame every time you answer his question. LMAO
Haha 🙂. But mostly WOW and Woh .. and 🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔 so, hmm .. but it is unclear where this dark energy (vacuum energy) comes from?
And to truly understand this I guess I need to go study Noether's theorem and Lagrangian mechanics (more) and pff you mentioned some terms and equations I never even heard from .. so could you give me some advice?
One of your best imo 👍!!
3:04
I appreciate what you did there.
Thanx for wrecking my brain every day!! keep it up!!
You're welcome 👍
I'm fond of your explanation of energy. So many people are using that word incorrectly, or have incorrect ideas about what energy is. Great work, Nick.
What is his explanation of energy? (i.e. what's the correct explanation)
@@localverse he has a video about what is energy, you may watch it, its great too
@@Kislay11 that video was the reason how I discovered this awesome channel on UA-cam
@@localverse What the HECK is Energy? ua-cam.com/video/snj1wBtn6I8/v-deo.html
@@ScienceAsylum
Precisely the video I'm referencing. As eloquently/simply explained as I've ever seen.
Using combinatorics and the statistical mechanics interpretation of entropy, I predicted the breakdown of the 1st or 2nd law in an asymmetrical universe when you add the cosmological constant. And now I found this video. Wow. I feel like a genius.
What do you think about this?
If you say energy must have a constant rate of change per unit time, you solve everything super nicely.
Energy by definition only means something *over time*, because really, what you care about is *not* conservation of *energy*, but actually conservation of *work*, which is just the transfornation or "consumption" of energy over time.
You can gain energy, but you can't gain work.
You can then redefine the cosmological constant not as the rate of change of the expansion of space, but instead as a rate of how quickly time slows at a given velocity.
This is scarily similar to the thought experiment of how light speed travel would effect your perception of time relative to other objects.
The expansion of space is by definition absolute and goes against the core of relativity, but the slow of time by an amount proportional to speed is relative and produces the same perception, or others which differ by the relative speed of an object.
If it takes longer to reach a destination, it is perceived to be further, but that does not mean it is, just like traveling towards or away from galaxies causes the light to shift, which you could potentially explain as the exact same phenomenon, as relative movement to the light we perceive slowing or speeding the passage of time.
That would imply that light red shifts as it travels not because the space it travels through is growing, but because our perception of how much time has passed for the light to arrive has grown from a strictly linear amount.
In other words, time can be thought of as a rate of change of velocity as much as velocity can be thought of as a rate of change of time, they are both equal quantities by this definition.
Just let go as soon as u redefine energy lol! Your awesome nick glad to c u again on this
This is actually the video that brought me over here.
One of my friends shared when i brought up the topic
Isn't 1:40 incorrect. There should be some kinetic energy left at the top, because a squirrel still has horizontal velocity.
CRAP! No matter how much I double and triple check things, there's always a mistake. I'll pin a comment.
Great catch!
Conservation of Information shall not be violated! Its good to see you plug your book again. It's a very useful book. Whatever next, posters?! 😀
I'd love to make that types of energy chart into a poster, but it needs to look cooler. I need to talk to my graphic design friends.
Very good video!! Keep on doing these!!!
Great topic - challenges the current thinking. But, quite reasonable once you apply the cosmic time scale aspect and its affect on time translation invariance. Fascinating.
Energy is always conserved!
Expanding universe, "Hold my beer."
Conservation of energy works for closed systems. An expanding universe is NOT a closed system. It's that simple.
I think. 👍
It is, no energy is added from the environment, infact there is no observable and as far as we know, intractable environment, so it's a bit more complicated than that.
Maybe what we think of as dark energy is merely energy and matter existing in parallel universes. Point in favor for many-worlds interpretation of quantum theory?
@@neil2444 it makes no sense, at all. Why, and how, would parallel universes interacted with ours, and why in a way that they transform energy from their universe to ours, and in a very specific way, that it is spread evenly in the whole space
@@pawemarsza9515 How does dark energy interact with us at all? It's just a theory, and it makes as much sense as claiming 80% of all energy just exists, despite not having any proof of said energy. My point was just that if positioning of particles is a probability wave function, then finding that particle in its most probable spot is just a sliver of that entire probability wave function. Maybe the universe is the whole probability wave function, not just the sliver where you find the particles.
Love your videos! I do think its important to state a theory when it arrives in our conversations. Dark Energy is still a theoretical postulate to fill a space of physics we don't understand isn't it? The CMB is also our best theory and has yet to be proven as anything other than the furthest we can "see" in our 4D understanding of the universe. In all tests of the 1st law of thermodynamics, conservation of energy prevails true experimentally. Keep up the great videos and I appreciate all the time you put into explaining complex topics simply.
Crazy stuff in the true sense of the meaning - love it!
One of my favorite channels. And fry was in the hitchhikers movie. The good one. Mos Def
Isn't CMB just spread around the universe and red shifted, like light leaving from close to a black hole?
Yes, it's more spread out, but that's not why it's losing energy. There's still the same number of photons, but now they're all at a lower frequency. That means the _total energy all together_ has gone down.
@@ScienceAsylum yeah, but photons leaving a gravity well also loose energy due to red shift. Does the conservation principle break there also?
@@tedarcher9120 Yes, you are correct I think.
For Black Holes the situation is a little bit more complicated. The question is always the same: does the system photon-black hole has time traslation invariance? If and only if the answer is yes, than the TOTAL energy is conserved. For the most archetipical black hole, the Schwarzshield one, it is true and the total energy of the photon is conserved. But a gravitational red-shift is indeed present, as the photon travels away from the BH, it appears to red-shift, and the energy measured by different observers is different. This is because, loosely speaking, the photon acquires gravitational potential energy relative to the BH as it goes far away. The concept of gravitational potential energy is usually ill-defined in General Relativity, but for some BHs it can be a useful concept and it is not cheating, we have that the total energy is conserved, it is just that it differs from the energy that different observers measure.
For the cosmological red-shift the story is different, the object that defines distances in GR, the metric, changes with time, hence we have no time traslation invariance and the photon's energy dilutes away as it travels through an expanding universe, energy is truly lost.
@@leobidussi5039 photons don't have mass, so they can't have potential energy. Red shift is happening when photon is travelling from more compacted space near black hole into less compacted, and thus redshifts. Literally the same thing happens with cmb, but the whole universe
Damn! You should have been reclining on a chair & doing from a beer bottle (or perhaps a test tube?) when you said, "Boy, that escalated quickly..."
😂
Freaking love your channel and your personality!
Best science videos on UA-cam.
Can dark energy theoretically be harvested? Like by connecting two very distant part of the universe with elastic ropes? What would the power output of such a system be?
AFAIU no, because putting energy which is already equally distributed (in equilibrium) to work would decrease entropy, and therefore violate the second law of thermodynamics.
(Kinda like the hot high-pressure gas in a combustion chamber has lots of energy, but it will not expand & make the piston move one bit if it's just as hot & dense outside of the piston. PBS Space Time did an episode on zero-point energy.)
The huge rubber rope is a nice thought experiment, and I haven't figured out yet why it wouldn't work. :^)
I don't think dark energy works that way
As for the power: Dark energy is spread around incredibly thinly, with a constant density of a couple *nanojoules per cubic meter.* That should be an upper bound, and it's not a lot.
Not sure how that would translate to power per length of rope (disregarding that it can't work b/c thermodynamics), but only using 1 dimension of the 3 expanding ones probably doesn't help? ^^
* It only makes up ~70% of the universe's total, because the universe is mostly empty space with barely any matter (dark or regular), but just as much dark energy per volume
nibblrrr I watched that video on PBS Space Time too and I understand what you mean but I think my design is fundamentally different from that piston. It might not work because of locality though.
nibblrrr Why would my system violate the second law of thermodynamics?
Wait so everything gonna disappear over time (if every mass turned in to light and no black hole )?
Yup
And since we are in a simulated universe, we will eventually pixilate and disappear.
Only the energy of photons is lost as they travel through an expanding universe. Massive particles retain their energy and experience no cosmological red-shift. Whether or not matter itself will decay away on cosmological scales is a question for the Standard Model of particle physics, as far as General Relativity is concerned they are not affected at all.
Basically we are not allowed to travel beyond the local group of galaxies because of the expansion. The rate is so high that it's higher than the gravity pull, the groups will escape from each other and accelerate above the speed of light.
Yeah, is called "Heat Death of the Universe". And it will happen at the end of the Dark Era of the universe (which will be around 10^1000 years from now)
Nick, you're the best man! Thanks
I like this guy, he includes all the caveats and edge cases. And this is one.
It's possible to stick an extra term for spacetime into the energy density of the universe such that it's still conserved. But that quantity is dependent on the coordinate system you choose. In other words, it's not a thing, not physical, just a bookkeeping contrivance.
If I recall correctly, this whole issue really hung up Einstein when he was developing general relativity. He felt there ought to be a conserved contribution to his energy-momentum tensor for spacetime itself. But he couldn't do it in a coordinate-independent way and he eventually just gave up on it, which let him move forward. Not long after, Emmy Noether clarified what the trouble was.
I felt pretty flattered the other day when my brother (who is in the last year of his physics degree) asked me for help in understanding the quintessence of dark energy, even though I am merely a 17 year old who reads Wikipedia articles and the linked papers at the bottom. Just felt like saying that this channel is where my interest in everything physics started, ha. Thank you Nick, you will always inspire younger scientists!
I don't think we should redefine energy we can consider these events as special cases
Special cases don't exist. Either energy is conserved and we don't understand what the expansion of space-time is, or we don't understand what energy is.
This make us more eager to find what dark energy actually is
Sure dark energy will be as a key for a lot of questions
I've had questions about this for a while. In another video, someone showed that Planck's constant is used in the measurement of energy in a photon. This makes sense that the smallest indivisible unit of measure for distance is used to measure the smallest indivisible unit of electromagnetic radiation, the photon.
How though, does the universe expand the fabric of spacetime? The two possible methods I can see is, either it just gets larger, inflating through increasing the size of Planck's constant. You increase the constant, and everything gets larger, stretched out.
The other way, is new space is added somehow. Some some portion of space has a specific number of Planck measurements and then it has one more than it used to. So, space expands at the fundamental level by increasing its dimensions, thus adding to its ruler. Basically, at one time you had thirty skittles in a row, then over time you have 31. Over time, new skittles get added, increasing the total.
In this scenario, couldn't it be that as a photon is traveling through space, this expansion stretches the photon, adding space to it too? In this event, the photon stretches past the indivisible size of a single photon and divides into two photons. In this way, the energy, thus the frequency, is divided amongst the photons. Each contains carries a lower frequency, divided from the total original frequency. Thus, the energy is divided up amongst the photons and not lost.
That makes more sense to me than so much energy just going out of existence.
You're so funny🤣🤣...I like your videos and the way you explain an interesting topic.👍🏻😃
Great video, but I'm confused by one thing: Why isn't the dark energy density simply decreasing?
We don't know what it is and where it comes from.
Maybe the ernergy could be conserved if we could mesure the transfer of ernergy into dark energy. (highly speculative, because we don't know)
Dark energy is an extra term in Einstein's field equation(how matter curves spacetime), so it may seem that physicists can just add whatever term into the equation to explain anything. But there are certain principles that these extra terms have to obey, and these principles imply that the dark energy density must be constant. Specifically, a non-constant dark energy density violates the local energy momentum conservation condition, which is still true in GR. It is the global conservation of energy(adding up all the energy/momentum in a finite region) that is violated.
@@lezhilo772 Makes sense.
@@lezhilo772 since we don't really know what dark energy is, maybe we are missing something here.
@@raduarghiros7364 Yep you are right. This is what our current theories say, but it is entirely possible that they will be proven wrong in the future.
6:26
Ahh, he looks so sad 😥
Simply - Thank you Nick
I welcome my new Warden YDT, you the real MVP