What is energy?

Energy is one of those confusing physics terms that has both familiar and technical meanings. In this video, Fermilab’s Dr. Don Lincoln sheds some light on what physicists mean when they say the word, as well as some truths about energy that would shock his high school physics teacher.

Non-conservation of energy in general relativity

Origins of mass video

Emmy Noether video

Fermilab physics 101:

Fermilab home page:

[quantumrobin]

I have no formal education in physics, just a lifelong fascination with the limits of what we can know about the universe, Dr Lincoln has been one of the most easily digestible educators out there, many thanks ❤️

[ucrohenry]

I like Dons way. He describes the fundamental topics of science in an easy to understand way, but he never talks down to you, . You are an excellent teacher, Don

[GH-oijf]

The only thing that surprised me was the mention of Émile du Châtelet. I have been reading the history of science for sixty years but somehow have never heard of her. I am satisfied to think of energy as the capacity to do work.

[danvartan]

"If mass is just energy swirling in a single location, with the swirling energy not moving - basically a stationary tornando - then we're back to the definition of kinetic and potential energy".

That's mind blowing! 🤯

[lugiaxgen]

Ive been watching this channel for a while now. As a 6th grader, i never really understood my teachers, I thought everything was complicated and very difficult to learn. Thank you, Don. I can guarantee if this channel was the only reason i was able to achieve good marks in my physics exam. Much appreciated, keep it up.

[TerryBollinger]

It's worth noting that interpretation models also have symmetries. Under implication symmetry, "time symmetry implies energy conservation, " TS>EC, forms a doublet with "energy conservation implies time symmetry, " EC>TS. Another successful physics search rule is "simpler is deeper." Under simpler-is-deeper, Noether's delightful and beautiful TS>EC argument places Minkowski's infinitely differentiable and functionally complex spacetime to the left of a small set of conserved quantities. EC>TS, in contrast, places the conserved quantities, including energy, to the left of spacetime and hypothesizes that sufficiently complex conservation scenarios approximate Minkowski's spacetime. Besides scoring better under simpler-is-deeper, EC>TS ("Rehteon's theorem") also removes the needless century-long separation of relativity and quantum theory that Minkowski created by inserting a concept of spacetime whose precision exceeds anything possible with Einstein's original 1905 real-matter clocks and rulers. EC>TS, in contrast, unavoidably requires space and time to be variable-resolution quantum properties of matter.

[seanurquhart]

I watch a lot of youtube shows related to physics explanations. PBS Spacetime, ScienceClic, The Science Asylum etc... This is the first time I've ever seen something like the backdrop of a chalk board with things that I am surprised to say I actually recognize the writing on. Whenever I've seen similar backdrops, I've always glossed over it as nothing I'd be able to make sense of but this time I looked and couldn't believe I recognized over half of it. I love all of you educators that break down the concepts in physics to the rest of us. I may still not be able to solve any of those equations, (I only took basic calc) but the fact that I can now just recognize them and what they represent is awesome. It makes me want to learn more math again. Thank You.

[tomato]

Another exquisite video, thank you Dr. Lincoln. That said, I'm sticking with Dr. Richard Feynman who said, "It is important to realize that in physics today, we have no knowledge of what energy is." "Energy is the interaction and motion of fields..." - a much more eloquent description than "the ability to do work" but still unsatisfying in defining what energy actually IS. Just a layman but my two cents.

[Bodyknock]

The one thing I've never liked about the term "energy" is that sometimes it's used in reference to a property of something (e.g. the energy of a photon) while other times it refers to energy as "stuff" in its own right (e.g. when someone says that photon ARE energy flying through space). I definitely prefer the former use over the latter. Saying that energy is "stuff" is a bit like saying "height is stuff". It's not actually a thing that exists on its own without context though, it's a property of things that exist in fields. It's kind of like how velocity isn't an object, it's a property of an object you can measure. Same with energy, it's not an object itself but a property of objects (some which have mass and some which don't) that you can measure.

[larrye]

This channel has helped educate me on many things that previously had been beyond my level of understanding. I still get a little confused on some things but its becoming much more clearer on how things in physics work. Thank you, 🙂👍

[timsmith]

@Fermilab, and @Dr. Don Lincoln, thank you for trying to educate us science enthusiasts. 😊 Dr. Lincoln is a great teacher and luckily mankind will always have these lectures.

[caela]

This is the single best, intuitive description of potential energy I've heard
Before, all I could ever find was either vague or just not something that could be measured in any real way

[joseraulcapablanca]

Thank you Doctor Lincoln, I appreciate your efforts to educate us and I try to learn. Keep up the good work.

[mkh]

I think there's no one video or book explaining the concept of energy this much simple, complete and at the same time persice. It fulfils different physics knowledge levels. Thanks a lot.

[dosomething]

i loved your historical discussion of the evolution of the notion of energy and momentum. please have a series of videos about this historic evolution.

[totheknee]

I like your description. So many people think that energy is a physical, tangible "thing." As if someone could "get" an energy and carry it around in their pocket. But really, it's just an abstract concept. Like you say: "a capacity." Or an ability. No one says they can carry a capacity around, just like no one says mystical "ability to move things" pours out of crystals and into one's hands. But they say that about energy because it's almost completely misunderstood by the majority of people. Even a high percentage of physics students get it mixed up.

[Kerrnano]

Another incredibly informative video from Fermilab. These are top knotch, please keep spreading the knowledge

[robinseibel]

This was beautiful. It's always amazing to get a new insight and a different perspective so that you can modify or re-interpret what you've learned. I remember a grad school prof saying that every time he read "Feynman Lectures on Physics", he learned something new, and this was a person whose colleagues considered him to be brilliant. This video was like that for me.

[hansg]

We miss the 'stache Dr. Lincoln!
Thanks for bringing this educational content to anyone who's willing to listen.

[Sigmaairav]

I'm suddenly imagining gravitational wells around or within every single person object and thing. These wells when they intersect, like water droplets, can get larger in radius in direct proportion to the amalgamated mass focused into a single space.

I think that if enough of these gravity wells accumulate, they create the planetary scale gravitational effects we see. Just as merging black holes result in a larger event horizon.

The warping of spacetime is only strong and noticeable on larger scales but on smaller scales I imagine it is there. Everywhere there is mass, there is a warping of spacetime, a "gravity well" at all scales. Weak at small scales, strong at accumulative large scales. There might not actually be any "gravitons" and instead gravity may simply be an emergent property of mass at sufficiently large scales and/or mathematical extremes.

Since mass and energy are considered equivalent, it can then be thought that gravity is therefore just another property of energy as it affects spacetime dependent on how much of it is concentrated in one place.

It could also also be said that the more massive a thing is, the more "energetic" it is; the higher it's energy content is.

I'm just an autistic lamen though. All of this fascinates me