What is Energy?

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Energy is the most powerful and useful concept in all of physics, but what exactly is it?
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Previous Episode:
Kronos: Devourer of Worlds
• Kronos: Devourer Of Wo...
Written and Hosted by Matt O'Dowd
Produced by Rusty Ward
Graphics by Matthew Ranker
Assistant Editing and Sound Design by Mike Petrow and Meah Denee Barrington
Made by Kornhaber Brown (www.kornhaberbrown.com)
In physics energy is not a substance, nor is it mystical. Energy is a number. A quantity. And the quantity itself isn’t even particularly fundamental. Instead, it’s a mathematical relationship between other, more fundamental quantities. It was 17th century polymath Gottfried Leibnitz who first figured out the mathematical form of what we call kinetic energy - the energy of motion. He realized that the sum of mass times velocity squared for a system of particles bouncing around on a flat surface is always conserved, assuming no friction and perfect bounciness. Leibnitz called this early incarnation of energy vis viva - the living force.
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Опубликовано:

13 фев 2018

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Комментарии : 2,5 тыс.

@astrowuff 5 лет назад

No energy was lost or harmed in the making of this video

@Joemamashouse69 4 года назад

Some energy was dispersed into a higher entropy state though

@bestonyoutube 4 года назад

Yeah it was all just a huge waste of time.

@astrowuff 3 года назад

@Draw your life no my friend nuclear bombs merely transform energy held within the nucleus of atoms. I think you're thinking of mass when a small amount is turned into energy during any explosion. And yes even though mass is turned into energy, energy was not created or destroyed because remember Einstein's famous equation says that energy equals mass times the velocity of light squared, so mass is energy. Mass is an emergent property of certain particle interactions while energy is a fundamental property of the universe. So you can create or destroy Mass but you can only change the distribution of energy.

@astrowuff 3 года назад

@Draw your life Yes Matter (not mass) contains a lot of energy. So its not created or destroyed but merely trapped. "Destroying Matter" merely releases the trapped energy. Most matter was created at the big bang though so we often don't think about the energy it contains because its been trapped for so long. When the sun fuses elements into heavier ones, it releases a tiny amount of the trapped energy within matter. Similar with fission as Iron is the lowest energy state that stable atoms can be in.

@astrowuff 3 года назад

You can also create matter from energy. There are physics labs that create a small amount of matter and anti matter by concentrating energy to a small location then filtering out the matter and anti matter. It takes a lot of energy to create a tiny amount of matter though.

@ekaramdani6390 6 лет назад

"a physicist sees a guy standing in the rooftop and shout don't do it you have so much potential" For whatever reason i instantly laugh so hard

@StickyTank 6 лет назад

far too hard to be OK xD

@genkidamatrunks6759 6 лет назад

Long as it doesn't last more than 3 hours he should he fine. Any longer and he might want to seek a physician.

@Baamthe25th 6 лет назад

The stoic delivery, and just the unexpected nature of seeing this in a PBSSpacetime vid made it for me. I knew the joke already, but I totally didn't see it coming. I was seriously getting ready to think/paying attention to the intro.

@Nexus2Eden 6 лет назад

#MeToo

@RajSingh-qc6lq 6 лет назад

#MeToo

@TheWyrdSmythe 6 лет назад

“Don’t jump; you have so much potential!” I’m still laughing! 😂

@anarchyantz1564 2 года назад

Unless it is Einstein seeing the guy on the roof, he was always keen talking about people falling off them. From a purely equation perspective of course.

@DallyDragon 6 лет назад

"Lithium is grunge, not metal" That's the best thing I have heard all day!

@LuisSierra42 3 года назад

Nirvana forever

@spwicks1980 3 года назад

@@LuisSierra42 Was about to get all upity about "in my 20+ years of chemistry, i've never heard it called grunge".... then got it finally :P

@aminlah8027 2 года назад

What's grunge?

@anarchyantz1564 2 года назад

@@aminlah8027 Oh my young sweet summer child...."Passes you a CD with Nirvana, Smashing Pumpkins, Pearl Jam and Alice in Chains on". Here is your research material, they will be on the exam. :)

@problemecium 6 лет назад

At least Space Time is here for me on Valentine's Day.

@drew8443 6 лет назад

Yeah, good thing there's something to cheer us up today. I really love how deep these episodes became lately Hopefully SE 0.9.9 will be there for me on my birthday ;)

@MellowWater 5 лет назад

😂😂😂😁😁😀😀☺☺😐😐😟😟😟😧😧😭😭😭😭😭😭😭

@Sonicboum3 6 лет назад

"Mom, i'm not doing anything, i'm just conserving my potential."

@jonathankehn9202 6 лет назад

"son, use that potential energy and take out the trash or my kinetic energy is going to apply force to your butt.

@PuzzleQodec 5 лет назад

"So dad can I have another burger? I need more potential."

@Saurabh_Tewari007 4 года назад

It looks like you didn't understand the concept well 🤣

@madcircle7311 4 года назад

Mom: You need to be more kinetic.

@PUTURHANDSintheair22 4 года назад

Jonathan Kehn he can't use that energy cuz first of gravitational potential needs a height/Y-axis taking out the trash would generally be working with the x-axis and since ur height doesn't really change in that action or gravitational potential should be the same for the most part, therefore he can't even use that potential energy, unless he was in the second floor and the mom threw him out the window into the trash then he can make use of that potential energy, C'mon bro do u even physics

@kataseiko 4 года назад

You seem to have skipped the part that explains "what is energy?".. However, it appears that nobody can exactly define what it is. Leibnitz and some others defined it as "the potential to do work". I have not seen or heard any better definition yet.

@egregiousqueef7781 2 года назад

If bored, read Leibniz views on God (and perfection and theodicy, etc)

@Bronze_Age_Sea_Person 2 года назад

Aristotle has a good philosophical approach to potentiality and actuality, where the term energy came from. he was specially against the numerical approach to physics though, but well, quantitiable and measurable things which we can assign numbers are just an aspect of reality

@aliismail2962 2 года назад

You seem to have skipped part of the video. At the beginning and @9:40 he says what is energy in physics, its an accounting tool, a concept we created to relate more fundamental things together. There is no physical thing called enegery that exists out there and that flows and transforms, as some woo woo gurus would like you to believe.

@bennettlewis5495 2 года назад

@@aliismail2962 If that's so, what "travels" down (around) wires? It has effects that we can predict. What is it? Accounting tools don't have effects, they just keep track of the effects. So, what is energy?

@flexico64 2 года назад

"Energy is a number." 0:53

@xunxekri 5 лет назад

0:06 I died. Like, collapsed onto the floor. My heart stopped beating. That was amazing.

@user-dk7eq9fc8e 6 лет назад

Haha that intro punchline

@Abc-tx4zr 5 лет назад

I look like that pos in your profile pic fuck

@yugchauhan4890 6 лет назад

Hey matt i am an 11th grade student but due to pbs spacetime and infinite series and some other channels made me develop intrest for quantum mechanics. Now i have finished 'Introduction to quantum mechanics by david griffith'. Thanks🖒🖒 Ps:- I am a Biology student and giving NEET in 2020

@egonieser 6 лет назад

Yug Chauhan Keep at it and you might just one day stand next to Matt. In my case - they taught most of this at school (yeah, our school teaches physics and chemistry (mandatory) from 5th grade upwards until University) couple of years of astrophysics aswell, sadly I found it utterly boring, being a lazy teenager and all. Now I totally regret not listening. While most things jog a memory here and there back to my school days, most of it I have to relearn again. So keep at it and pursue your dream.

@pbsspacetime 6 лет назад

Hey Yug! If you're in 11th grade and have already finished Griffiths then the physics world needs to watch out for you!

@gibranhenriquedesouza2843 6 лет назад

Congratulations! I finished Griffiths in the 4th grade, of physics' graduation!

@daveb5041 6 лет назад

You should read the bible instead and learn creationism by ken hamm. Ever wonder why bananas are curved unlike earth?

@Sophistry0001 6 лет назад

Dave B - Checkmate, atheists! You got em.

@xtreme0915 3 года назад

They couldn't have picked a better person to deliver the content on this channel. Matt has the most relaxing voice, anybody else put on space time before bed? I love the content of the videos, but inversely I can also just listen and let it lull me to sleep without fail. Growing up is weird 😜

@thenovicenovelist Год назад

I have anxiety issues, so I've recently started listening to these videos before bed because learning helps me relax. So, I fall asleep easier after watching a couple of his videos. They are interesting and relaxing. Not boring.

@lindy9196 5 лет назад

So... what's energy? You seem to have skipped that part.

@kbee225 4 года назад

Energy is a fundamental property of particles. All things have it.

@kbee225 4 года назад

@@hiimpact3669 I think the spacial transformations are caused by energy. Not the other way around.

@michaelsommers2356 4 года назад

He didn't skip it; he said it is a bookkeeping aid. See lecture 4 of the Feynman Lectures: www.feynmanlectures.caltech.edu/I_04.html

@chakubanga1 4 года назад

He jumped on Newton's head and started bashing, other scientists with Einstein's energy 🤪🙄🤪🙄

@Tachsman 4 года назад

Energy is energy, too bad, there was so much potential here which was wasted.

@anywallsocket 6 лет назад

This could've gone into Gauge Symmetry, which would've been VERY interesting - albeit difficult to explain accessibly, but if anyone can pull it off it's PBS SpaceTime!

@carlz28 3 года назад

Still wouldn’t have told us what energy is. Just like the video....didn’t.

@RallyCarDelta 6 лет назад

What a cliffhanger! My guess is that it has something to do with spacetime and how energy is a representation of that effect. Next thing you know, Matt will tell us energy isn't real and it's only an artifact of our limited perception of our reality. I'm grasping at straws here. I can't wait for the next one. Best channel on RU-vid Matt. Keep up the amazing work.

@stevewhitt9109 Год назад

I agree. The more we know, the less we know.

@massimilianoc2436 6 лет назад

An amazing summary of key milestones of last 300 years of physics. Man, you know physics and no doubt you master how to teach it! Thanks.

@cloudpoint0 6 лет назад

Physicist Richard Feynman’s thoughts on Energy: “There is a fact, or if you wish, a law governing all natural phenomena that are known to date. There is no known exception to this law - it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call “energy,” that does not change in the manifold changes that nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or anything concrete; it is a strange fact that when we calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same. (Something like a bishop on a red square, and after a number of moves - details unknown - it is still on some red square. It is a law of this nature.) … It is important to realize that in physics today, we have no knowledge of what energy ‘is’. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. It is an abstract thing in that it does not tell us the mechanism or the reason for the various formulas.” www.feynmanlectures.caltech.edu/I_04.html

@dee5556 4 года назад

This is not a LAW but a theory!!!

@dee5556 4 года назад

You give a 300 year old theory more credit than is dew... The universe is infinitely more complex!!!! Explain how the Universe is accelerating its expansion using Newton's Theory? Or power circuits using superconductors. Or super fluids that defy gravity using capillary forces. Or try explaining magnetic energy... yes energy... using thermal dynamics? Or charging a capacitor through a load then using the power in the charged capacitor to power the same load? There are hundreds of other examples ignored by mainstream science. The fact is you have bought into scientific dogma!!! Which is not science at all!!!

@cloudpoint0 4 года назад

@@dee5556 Sorry but there is no theory called the conservation of energy. There is just a physical law by this name. The law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. The law only applies locally, that is, within a single system that has time translation symmetry, so it does not apply across the entire cosmos (e.g. between very distant galaxies). The law isn’t 300 years old either. It was discovered by Julius Mayer in 1842. It’s just 178 years old and it has been confirmed many times since using modern science. I’ve bought into nothing. I provided Richard Feynman’s thoughts on Energy. I understand the abstract notion called Energy well so I know that he is correct. But he is more articulate about Energy than me so I quoted his words. I await the publishing of your peer-reviewed paper overturning the standard understanding of Energy. There are no shortage of doubters and cranks but they never come with evidence. Until they do, I’ll stick with the masters that I understand. And the universe is actually quite simple, but big. Big is not complex.

@1005corvuscorax 4 года назад

@@cloudpoint0 " I await the publishing of your peer-reviewed paper overturning the standard understanding of Energy." Perfect!

@maxwellsequation4887 3 года назад

@@dee5556 lol

@dsolis7532 6 лет назад

At the 7 minutes mark I was like "This video could be named The Essence of Langrangian, Hamiltonian and Statistical Mechanics" then I had a nerdrgasm. I love this channel so bad!

@anarchyantz1564 2 года назад

*Passes you a tissue for your nerdgasm*

@Joanyan 6 лет назад

You matter Untill you multiply yourself times the speed of light squared Then you energy

@trailers1069 5 лет назад

😂😂😂😂✌

@axz647 5 лет назад

"Then your energy" and it's not a fact

@FirstNameLastName-tc2ok 5 лет назад

Blue Light76 you’re*

@axz647 5 лет назад

@@FirstNameLastName-tc2ok thxs

@a.wolfgang6423 5 лет назад

The Manan J you string

@MClaudeW 6 лет назад

Man... you know, this video has special relevance to me. In high school I remember learning about potential kinetic energy and being convinced that it couldn't be right and was just a tool for math. I went on to learn about space curvature and felt vindicated enough but still curious. Here you introduce concepts that both make it workable in my mind and motivate me to learn what it is in Einstein's work that made me so sure upon hearing it. Too bad I suck at math.

@Shalkar 2 года назад

Then focus on what it means in a natural sense. If these things are true, how are they applicable to things as we know them. What *is* life? What *is* the universe we inhabit? That's basically what I do. It's the new philosophy.

@gabington8990 6 лет назад

That Lithium Grunge joke at the end is actually next level.

@KungFuBlitzKrieg 6 лет назад

The way he holds his hands makes me want a Hershey's Kiss.

@BassNinja 6 лет назад

KungFuBlitzKrieg oh....... my...........god

@BassNinja 6 лет назад

I can't stop looking at it

@mykel723 6 лет назад

NO! You're not supposed to be telling everyone, now our brainwashing won't be secret. 😒

@tudorsike736 6 лет назад

Lindybeige would give this particular scholar's cradle a 7/10. Decent shape, but he needs to keep it closer to his chest ;)

@contingenceBoston 6 лет назад

Peter Hell -- thank you for your service.

@Ifslayanct 6 лет назад

The only thing getting me out of bed in the morning is needing to pee. Not feeling energetic.

@achatinaslak742 6 лет назад

Pee has potential energy, when it is in your bladder, and when it falls into the loo, it will have more and more kinetic energy and less and lees potential energy. Until it stops falling down. It is a pity, that you do not feel more energetic after using the bathroom at all.

@stevewhitt9109 Год назад

It's a clue to the deeper truly fundamental properties of spacetime. Wow, talk about avoiding the subject. Love you vids.

@arjoon 4 года назад

I love to come back to older videos and still get new insights!

@cosmic_gate476 6 лет назад

When I binged your channel I didn't pay attention to the fact that videos were released only weekly. The last week has been too long. Finally a video!

@YadraVoat 6 лет назад

People use "Bing"? I wonder if there's ever been a study on the "accuracy" of search engines' results. Anecdotally, I daresay Bing ranks poorly. [Edit: No pun intended, but I should have been proud if it were!]

@cosmic_gate476 6 лет назад

Yo yeah dude cause it totally makes more sense for me to make a shitty reference to Bing rather than use a conjugation of the English verb "to binge".

@gizatsby 6 лет назад

...tbh I thought you meant Bing too. lol. Probably because I usually hear "binged on x" rather than "binged x"

@JMac90_ 6 лет назад

I knew he meant binge

@cosmic_gate476 6 лет назад

I would say Occam's razor, but to be fair my perspective is from that of someone who doesn't use Bing nor knows anyone who uses Bing.

@lucasa.8223 6 лет назад

You can't finish a physics videos by stating that energy isn't conserved in cosmological scale and not further develop your statement. I demand a follow-up video!

@Mosern1977 6 лет назад

We are clearly missing some great parts of the energy-conservation equation. Since matter is condensed energy, and the universe is filled with matter, where does the energy come from? I guess it's the 'magic' Big-Bang creationist theory that magically explains it. And then we have the 'magic' expansion of space (dark energy) that for some reason increases the potential energy of everything (things get further apart = more potential energy), but doesn't seem to require any energy to happen. I so look forward to the James Webb telescope coming online, and then the astronomers will find some nice galaxies a couple of billion years older than the universe. I'll laugh when they'll retcon the BB theory again to fit those 'impossible' galaxies, adding some mumbo-jumbo physics to boot.

@AtomicFrontier 6 лет назад

I just made a sort-of follow-up with that concept applied to spaceship re-entry. Might be interresting :)

@cloudpoint0 6 лет назад

Solitary Mind, The universe as whole or over very large distances (megaparsecs) isn’t usually viewed as conserving energy since there is no common reference point for time (it lacks 'time translational symmetry'). But there is a conceptual way that the universe can be viewed as conserving energy. Dark energy is added to the universe, this a positive energy. But the universe’s total potential gravitation energy (or curvature) increases by the same magnitude, and this is negative energy in the cosmological accounting system. This isn’t practical for any calculations, so it is ignored, it’s just conceptual. motls.blogspot.ca/2010/08/why-and-how-energy-is-not-conserved-in.html#disqus_thread

@mikeclarke952 6 лет назад

It does follow from the logic presented here, but in the expanding universe case they use heat energy, not kinetic and potential energy. As the universe expands the heat energy changes(U) but without work being done, it's in the enthalpy equation.

@kalisticmodiani2613 6 лет назад

Also we don't know if we can consider the Universe as a closed system. Surely the observable universe interacts with what's beyond the observable limit.. And so on and possibly on an unlimited scale.

@stefaniasmanio859 6 лет назад

Never listened to anything clearer and more complete!! Super! Thank you so much!

@riazabdulla1658 2 года назад

I teach AP Physics 1, and this is such a great supplement to the work that we do in class. I teach some very curious students who will definitely appreciate this.

@olivercharles2930 Год назад

Your students must be quite *energetic*

@NitpickingNerd 6 лет назад

it surrounds us it penetrates us it binds the galaxy together.

@CataphractVardhan 6 лет назад

But unlike Energy, Dark Energy is accelerating the expansion of the universe, we must restore the Jedi Order. We must restore balance to the universe.

@Whitebeard79outOfRus 6 лет назад

And it means that eventually you'll have to change the Floors ;))

@minasoliman 6 лет назад

Major Grin may the energy be with you young padawan!

@NitpickingNerd 6 лет назад

To say that if the Jedi dies, the light dies, is vanity. Can you FEEEEL that?

@Mosern1977 6 лет назад

The 'Force' and 'Dark Energy' have one thing in common, they are both figment of the imagination.

@b3nsu 6 лет назад

A physicist sees someone standing on top a building and he shouts Convert your GPE into angular momentum, flipping your body as you hit the pavement!

@insertdeadmeme 6 лет назад

EVERYBODY DO THE FLOP

@user-pp6wy9tb9j 6 лет назад

*"Do a flip!"* - Bender

@somekindofdude1130 6 лет назад

Find the angle φ It's blue isn't it?

@cherrydragon3120 6 лет назад

Flipping *before* hitting the ground... i don't think you would do much flipping when your face hits a stone floor...

@exponentmantissa5598 6 лет назад

Wrong units. Potential energy is joules and momentum is kgm/s

@Kolajer 6 лет назад

Finally! Such a long wait for this episode. Thank you!

@alexjann5802 4 года назад

excellent information and presentation. So many interesting questions and directions to be explored. Truly enjoyed it

@fakjbf3129 6 лет назад

That opening joke legitimately made me pause the video so I could stop laughing.

@ConceptNull 6 лет назад

You are lying no one laughs at physics jokes, its more like ''heh heh yeah good one!''

@axz647 5 лет назад

@@ConceptNull kinda true

@ShitboxXx360 6 лет назад

Those 2 weeks we had to wait for a new episode felt like an eternity!

@achatinaslak742 6 лет назад

This experience proves, that time is not a constant phenomenon :). See other videos of PBS Space Time to learn more about the mystery of time.

@daryljonesfoster4102 5 лет назад

Put ya fingers away bro ...

@billymcnasty05 5 лет назад

I never learned so much without the question being answered at all

@TheGGreggs Год назад

Fabulous explanation of the conservation of energy AND the limits of the very idea of that conservation over time. Well done.

@djbslectures 6 лет назад

I would love to see a “what is entropy?” Episode or series.

@micheleyu3125 2 года назад

i make a video: Entropy and Happniess, about Entropy vs Energy!

@BanditRants 6 лет назад

Absolutely *LOVE* this channel. If you guys ever need an extra video editor I will always be willing to help free, pro bono. The need for more channels like this, and more content being produced from you guys is essential for the production of more quality content.

@redcomandante1875 6 лет назад

+BanditRants your content is absolutely incredible!

@jordysfernandez2157 6 лет назад

I wholeheartedly agree with your sentiment.

@piceusfox6140 6 лет назад

+BanditRants curiosity propelled me to your channel, and I'm glad it did.

@maestroanth 6 лет назад

Wow, cool offer man.

@overkill246 6 лет назад

Such fake replies like everywhere else you spam this

@peterb9481 Год назад

Top episode. Maybe the best. So much content. Love the comments at the end - including Sebastian’s. Love hearing all the scientists work - especially Emmy Noether.

@daaknait 6 лет назад

The feel when you realize that in every video, the subject matter ends with the words "space time".

@alarcon99 6 лет назад

Now I demand a Quantum Hamiltonian Operator rap and musical

@dankole307 6 лет назад

alarcon99. Sorry rap is not music. Jungle drums.

@SybotLV5 6 лет назад

Different subject, but someone made a song taking a paper and using the abstract on Quantum Decoupling Transition in a One-Dimensional Feshbach-Resonant Superfluid: watch?v=FIXRXMMlZBM

@MaxwellsWitch 6 лет назад

I brought my homeboy operator J_z, famous rapper of total angular momentum. I brought a^{\dag}, don't mess with him because his adjoint will deck your ass. #SpinUp The time reversal operator died for the #SpinUp movement. #SpinUp son

@danielcookman3971 6 лет назад

alarcon99 You're in luck! Here's an acapella version of the Hamilton theme, based on the life of physicist W.R.Hamilton, featuring a bunch of science youtubers!

@BlaveKaiser 6 лет назад

Next episode: What is Information?

@agimasoschandir 4 года назад

You won't get it. By hook or crook

@SouthernHerdsman 3 года назад

binary bits

@freedomisnotforsale 3 года назад

Information is entropy

@vol230 3 года назад

@@freedomisnotforsale what's entropy?

@freedomisnotforsale 3 года назад

@@vol230 blood of gods, essence of the space and time, and result of universe decay.

@calvingrondahl1011 3 года назад

“Not wrong just more interesting.” I love that.

@SKULDROPR 6 лет назад

these videos are like foreplay to me. I'm always waiting until he finally says 'in space time' right at the end. gives me the jollies. that is all.

@angelic8632002 6 лет назад

Might be easier to just ask what isn't energy :3

@achatinaslak742 6 лет назад

This is a very good question, and a good one for a next video of PBS Space Time. I think, it is even more difficult to tell, what is not energy, then what is energy...

@angelic8632002 6 лет назад

+Achatina Slak Especially when you get down to the quantum level of things/reality. That's when it gets real weird and you start to wonder what the relation of energy really is to the world. Or if its all just a potential in different forms.

@Familia_nepal_nepal_do_mal12 6 лет назад

In the same time, energy is just mathematical formalism that is not fundamental. So nothing is energy.

@Polemarchus404 6 лет назад

Low Energy Jeb

@TilveranWrites 6 лет назад

Exactly! Is seems like everything that physically exists is made of it, and there isn't anything else.

@ilikeycoloralot 6 лет назад

BS in Mech Engineering here. Thanks for all your videos! Keep up the complex ones! Can't wait for Unruh and Noether!

@facundorodriguez3315 6 лет назад

A whole episode about symmetry and super symmetry would be nice =)

@cristianholtheuersearle9648 5 лет назад

i didnt expect the "potencial" joke, caught me off balance and made me laugh at work xD

@MichaelOrtega 6 лет назад

They say if you are early, he might give you super energy

@banter7663 6 лет назад

Michael Ortega they say if you are early enough, a black hole will appear under you and swallow you.

@user-vz7mu4su9n 6 лет назад

All we know is that it's called PBS Spacetime

@carlz28 3 года назад

They literally did NOT say any of that. n00bs!

@TheArtofFugue 3 года назад

well, i suppose i’ve missed that window.

@sandyvilletet5989 2 года назад

@@banter7663 eeèeeè

@Gam3B0y23r0 6 лет назад

PBS SpaceTime is the best !!

@paulthompson9668 6 лет назад

Yes, I'm sooo looking forward to their video on Emmy Noether.

@jeevin03 6 лет назад

Does this mean when space gets compressed due to , let's say a gravitational wave, light's wavelength shortens and at that moment it gains energy from nothing ?

@garethdean6382 6 лет назад

Yes, and the cosmic microwave background has been stretched, losing energy. There ARE ways to get around this, involving the energy of curved spacetime but they can be a bit tricky to visualize.

@pierreabbat6157 6 лет назад

Noether's theorem is not to be confused with No Ether's theorem, which was proven by Michelson and Morley.

@revenevan11 2 года назад

3yrs later, this comment is still under appreciated!

@JohnStephenWeck 6 лет назад

Greetings everyone, this is my working definition of energy. “Real energy” means the change in a system. Typically, when people talk about energy, they specify which flavor of change they mean. If you remove time, you remove the energy (because nothing can change). Energy is never a substance, nor can it be negative (because of the unidirectional nature of the time dimension - there is no true negative change in our universe). Energy is just an observed characteristic of various changing systems. “Potential energy” just means that during normal operation, a system owes you some specified flavor of changes in the future (you are in effect, saving changes). For example, a city needs extra energy to change things in it (because they mean the same thing). So, a power plant is really a “change source”. If you have a battery as a power supply, you really have a “pool of changes”. If you disconnect all the change sources (turn off the power), you will starve the city of changes (and everything grinds to a halt, a bit like in the “The Day the earth Stood Still” movie). No energy means no change. More speculatively, regarding the nature of "change" in general: a. Something must change (this is the structure of the universe - aka, information). b. Changes can occur in both space and time (due to the existence of space-time). c. Changes should be no-time entities (not imply time-only). d. Systems that change a lot, in the time direction of space-time, are called “energetic”. e. Systems that change a lot, in the space directions of space-time, are called "dense". f. “Lots of change” (in both space and time) means the same thing as lots of space-time bending (like gravity). g. This why dense or energetic systems have lots of gravity. Thanks for listening. ;)

@pelemariusv 5 лет назад

Thanks a lot!

@Garmashua 5 лет назад

John Weck Oh bro) Is ))) Energy is scalar physical quantity, which is a single measure of various forms of motion and interaction of matter, a measure of the transition of motion of matter from one form to another. You can not transmit energy. And it doesn’t have form. And yes, it cannot be destroyed.

@Garmashua 5 лет назад

John Weck finally smart comment

@arnavshah599 3 года назад

Well done ,

@bendavis2234 3 года назад

How would you differentiate energy from entropy? Thanks for the detailed explanation. I've been searching for an intuitive definition of energy forever and your description is the best so far.

@sebastianelytron8450 6 лет назад

Wait, you mean it's not something that comes in cans at 7/11?

@FireShell7 6 лет назад

technically it's also that

@MostlyPennyCat 6 лет назад

And coal and uranium. But don't eat those.

@jonathankehn9202 6 лет назад

I eat uranium. It's pretty good once you get around the whole "it's going to kill you" part.

@FrankSalman 6 лет назад

CALM DOWN MAN! It is, these guys don't know what they're talking about. My favorite is the one that you don't need a can opener, just pull up on the tab.

@fdsfds7339 6 лет назад

Sebastian Elytron wait... Youre the guy that said Lithium is grunge not metal

@jefferyriggs3974 4 года назад

I like your explanations, keep up the good work.

@hanssacosta1990 3 года назад

Love pbs space time just right before bed time!!!

@damirradoncic7390 6 лет назад

Hi Matt, followed your channel for years. Graduated from Uni a couple of years ago but love to hear you talk about physics, activates my brain in a way that normal life seldom does. Keep up the great work!

@captainconcernedsr.5360 6 лет назад

Midichlorian is the name of next energy particle. Im calling it.

@bigsby6bender 5 лет назад

Love this series!

@Saurabh_Tewari007 4 года назад

Matt's Head to body ratio is pretty amazing.

@jorgecardoso5863 6 лет назад

I love you Matt, you're like the Carl Sagan of modern time, with just double speech velocity

@MTHunter777 6 лет назад

Energy is... A. Light B. Second creation after void/dark energy. C. What everything is made of. D. Love manifest. E. All of the above.

@ethannguyen2754 3 года назад

“Don’t do it! You have so much potential!” *Cuts to an ad*

@curiousSloth92 5 лет назад

-"We all know what it feels like to be energetic! " -Ehm... No..

@The_KoRn_king 6 лет назад

I sleep a lot because I believe in conserving energy.

@aniksamiurrahman6365 3 года назад

U r wasting ur breathe, its already conserved. Now move ur ass and increase some entropy.

@serkorz3823 5 лет назад

Energy, a permission to do something (whatever).

@mikesawyer1336 3 года назад

Another ver good lecture... loved it.

@LambentOrt 5 лет назад

Matt's voice is so soothing... I watch/listen to SpaceTime videos as I slowly drift off into black holes of sleep... talking beautiful complicated nonsense that I can never hope to understand.... zzzzzz... thank you SpaceTime and Matt for ASMR-ing me to sleep...

@daveb5041 6 лет назад

Q: What is energy? A: Ability to do work. Next question.

@chrissonofpear3657 6 лет назад

And resistance to alteration of velocity, momentum or state vectors...

@richardbraakman7469 6 лет назад

The next question: what is work?

@ChenfengBao 6 лет назад

+Richard Braakman transfer of energy

@meaquidemsententia 6 лет назад

I despise that definition. It tells me nothing.

@tonikotinurmi9012 4 года назад

@@meaquidemsententia Go to school then. Dave B gave perfect answer.

@timbeaton5045 6 лет назад

Sad that it has only been relatively recently i have even heard of Emmy Noether, and now Émilie du Châtelet. Wonder how many other women have made great contributions to science that we almost never hear about. Maybe a Space Time special on some of the less well known women in science?

@garethdean6382 6 лет назад

Male discoverers of dark energy? Here's your Nobel, as soon as we could get it to you. Female discoverer (Well team leader) of dark matter? Dead now, never got one. There are so many stories.

@michaelsommers2356 4 года назад

You've never heard of most of the men who did physics, either. Physics is not taught historically. Basically, the only physicists who are remembered are those who get something named after them, and even then the most you know about most of them is their names.

@tillyqtillyq3750 4 года назад

The previous two commenters, Justin and Michael's wittle feelings are being hurt by the possibility that misogyny exists. Poor dears.

@brutusjudas5842 4 года назад

tillyqtillyq , you resorted to ad hom without provocation. That’s an automatic disqualification from civil discourse, not to mention any potential debate. The two commenters you referred to have officially and objectively defeated you in the short exchange.

@agimasoschandir 4 года назад

@@tillyqtillyq3750 Not only does misogyny exist, it persists [patting you on your pointed little head]. Maybe one day you too will be wise

@himynameisben95 Год назад

"We all know what it's like to have energy... to get up in the morning" can't relate 💀

@zrstopa Год назад

the trebuchet animation had me rolling. thank you.

@MrKrack-ri8ix 6 лет назад

What's the name of the background music at 4:05?

@fvveb2141 6 лет назад

Darude- sandstorm

@evanm2024 6 лет назад

I don't know if you read this... but I'm going to request a video on the off-chance you do. Can you explain the difference between the Lagrangian and Hamiltonian point of view? Not just mathematically, but what it really means?

@amisfitpuivk 6 лет назад

The math is what it _really_ means though. You want the humanized explanation, it is a ‘point of view’ after all which innately means it is subjective. I know what you mean, just pointing out that the words need to be careful in science, else we get bs like ‘evolution is just a _theory_’ etc

@theguy8521 6 лет назад

Lagrangian and Hamiltonian formalism are more or less equivalent mathematical descriptions of the same physical processes. For some the Lagrangian formulsm works better, for others it is the Hamiltonian that give the most insights. There really isnt much more to it than that. Neither the Lagrangian nor the Hamiltonian are quantities that can be directly measured, just like Energy cannot be measured directly but has to be computed using other measurements (for example mass and difference in distance and time in classical mechanics). So they are mathematical objects (with some physcal interpretation) that help to formulate the theory and compute other things. The only reason why you have not asked what Newtons formalism really means, is because you are so familiar with it that you have just accepted it. But of course the idea of a force is in some sense just as abstract than a Lagrangian.

@chrisstargazer5866 3 года назад

That opening line😂😂😂😂😂😂 epic!! Matt is the best

@osamamohamedien3257 6 лет назад

Excellent Episode, thanks

@william41017 6 лет назад

9:05 come on You guys are just throwing symbols around

@xcvsdxvsx 6 лет назад

My favorite is the sword!

@vacuumdiagrams652 6 лет назад

mathsbyagirl.files.wordpress.com/2015/10/tumblr_ms7xuthyhv1qc38e9o1_1280.png This is the Lagrangian for the whole standard model :) To be fair though, it's written in the absolutely longest, least useful kind of way. Physicists would never touch it in this form.

@CataphractVardhan 6 лет назад

Oh you sweet summer child. If you think that is throwing symbols around, you should look at the complete derivation.

@xcvsdxvsx 6 лет назад

+BER-SER-KER MORE SWORDS!? Does to dual wield?

@vacuumdiagrams652 6 лет назад

What do you mean "derivation"? This is the definition of the theory, that is, this is the starting point. This is the quantity you derive other things from.

@ChrisOakesCO 5 лет назад

Energy, the ability to cause movement or change. To transfer Energy.

@inversehyperbolictangent3955 5 лет назад

That was a great science joke at the beginning. Loved it! 😄

@msq7041 4 года назад

that "you have so much potential" got me rolling on the floor laughing my ass off

@erikc1775 4 года назад

My professor, with 40+ years of experience: You are wrong Me: "Not wrong, just more interesting"

@CoolYooToobDood 6 лет назад

This is one of the episodes I'm going to have to watch 37 times...

@carlz28 3 года назад

Took me only 1 time. Rookie.

@Dyslexic-Artist-Theory-on-Time 6 лет назад

Thanks for the info!!!

@iainballas 6 лет назад

As an Auditor for the last three years, I loved this video.

@MattiasDooreman 6 лет назад

So.. Energy is an accounting tool but more interesting? Fine, I accept it.

@michaelsommers2356 6 лет назад

Read the -first- fourth chapter of the first volume of the Feynman lectures.

@hermeticxhaote4723 4 года назад

Your mom does too

@ruzzotalizo 4 года назад

@@michaelsommers2356 I, < uo

@tebunhouthakakyle9380 3 года назад

Hermetic Xhaote ಠ_ಠ

@kindlin 6 лет назад

Oh. My. BGaaAAWWWDDD!! This episode was amazing! As an engineer, having learned _aalllll_ about energy throughout 7 years of schooling, this episode was spot on. It also somehow really boiled down the harder quantum stuff to something almost manageable. Amazing.

@ShahroseKhan 4 года назад

THANK YOU FOR SAYING THAT, that's EXACTLY how I felt!

@stefan-stocksmadesimple5241 6 лет назад

Wasn't listening in the beginning but still caught that one !

@phildurre9492 5 лет назад

cool, i will ask my students to look this video when they learn the subject, good work

@XIIchiron78 6 лет назад

I've had these questions for a while but this seems a good place to ask: Does inflation obey the conservation of energy? For example, do galaxies gain potential energy relative to one another as they are pulled apart? Or in other words, if you had a many light year long and infinitely strong rope (let's assume it's actively supported) attached to a large mass on one end and coiled at the other, could you extract energy from the coil spinning as it unrolls? And; Is Gravity itself relative in general/special relativity? Is apparent gravity relative to your reference frame? Does apparent kinetic or potential energy increase the apparent gravity of an object? For example, an object moving very near the speed of light has a greater apparent mass. But does it actually curve space to a greater degree? It seems like the answer must be no, because this would lead to objects appearing to collapse into black holes depending on your frame of reference. But how does this work?

@cloudpoint0 6 лет назад

*Does inflation obey the conservation of energy?* Maybe and sort of, in the sense that addition curvature is added to spacetime during inflation (a negative energy), and if inflation is like dark energy on steroids, then additional energy is added to each unit of space during inflation (a positive energy). The two should cancel. *Is Gravity itself relative in general/special relativity?* Gravity is just applicable to GR. In GR, gravity is explained in geometric terms (curvature) of space and time. Relative means two observers traveling in respect to each other may have different perceptions of time and space. So the answer seems to be yes for GR.

@cloudpoint0 6 лет назад

Sorry that I did not answer your more-specific thought experiment questions. I don’t know how to deal with a rope that is megaparsecs long. I think one end of the rope would not even be aware of what the other end is experiencing over that kind of distance, or at least there would be a huge time lag that you would perceive as a long stretching of the rope. I don’t think an object’s *apparent* mass has any effect on space curvature. An object’s *true* mass has not changed just because it is moving near the speed of light, and therefore its volume is still larger than its own event horizon and I assume nothing changes like it becoming a black hole.

@Blaze098890 6 лет назад

Energy is generally not conserved in GR and this is especially the case with the expansion of the universe. As photons get red-shifted due to expansion their energy is lost. Also mass increasing with velocity is a rather outdated concept. The effective force is what is considered decreasing with velocity in relativity now.

@garethdean6382 6 лет назад

An object moving faster will have increased gravity, but only to things that see it moving fast. An 'isolated' object like a single proton, cannot collapse into a black hole no matter how fast it is moving because from its perspective it is sitting still. (If it could , 'regular' protons could do so all the time.) Only when it's in combination with another body will such things happen. When this involves the cosmic microwave background the proton-photon pair can combine over a certain energy known as the GZKlimit. (Either the proton is moving fast, or the photon is blueshifted to a gamma ray.) So a fast moving body has a different gravitational effect compared to a slow moving one and this difference syncs up perfectly with things like length contraction and time dilation so that all observers will agree on what events occur, even if they disagree on the strength of gravity and time it acts. The rope doesn't work as 'infinitely strong'. But given such a setup you COULD extract energy, 'Big Rip' scenarios take this to an extreme. What happens depends on the tensile strength of the rope. Any body whose internal forces are greater than the expansionary force will simply hold together; space in essence will move out from them. So if your rope is stretched taut you can't get any energy from it, it either snaps or stays exactly the same. Of course, as noted, long ropes end up needing to take relativity into account when dealing with the forces on them.

@evilwizardington 2 года назад

well... I'm not an expert, but the answer I think is No. Energy, as the conservation of a system symmetries over time is tied to the spacetime. The inflation itself is a distortion of the spacetime. So it is not strictly an event caused by energy, but by the gravity (which is a distortion of spacetime). In that way, gravity is not relative based on the observer or the reference frame, as it is directly tied to the mass of the entity under observation (and its piece of spacetime affected), not the observer.

@andrewmcilveen4917 6 лет назад

Please do an episode on eternal inflation!!!

@sihlengema9155 8 месяцев назад

Finally, an episode I fully understand

@hgracern 4 месяца назад

Thank you, fab info. ❤

@MrPhilipe711 6 лет назад

Question!: Before the Big Bang, Can we consider the Universe with a state of infinite Potential Energy?

@carlz28 3 года назад

Ask your mom.

@WSmith_1984 2 года назад

Yes...... Imagine the otherside/outside of a black hole.

@ramuk1933 3 года назад

New symmetry/conservation law: If the universe has expectation/reality symmetry, then feelings are conserved.

@shardhas.p3917 6 лет назад

Fabulous!!! Tnk you again.. I’m new to your channel I’m going to look at some of your other videos now kp ip the awesome job brother. Amazing information ✌️&❤️..