Is gravity a force?

Is gravity a force? The answer to that simple question is remarkably complicated and depends crucially on the theoretical framework in which the question is asked and answered. In this video, Fermilab’s Dr. Don Lincoln takes on this surprisingly tricky question.

Quantum gravity:

Loop quantum gravity:

Superstrings:

Fermilab physics 101:

Fermilab home page:

[charmgezos]

So much respect for this man. The best explanations, sturdy, reliable, without long narrations or drama, but not boring either!

[johnBSadro]

I am a retired physicist pushing 80 years old. Whenever I see and hear this guy I am delighted to be here!

[LiquidAudio]

Great explanation, as an ex science teacher I really appreciate your answer. People so often shoot from the hip without realising how little they really know!

[TimSnodgrass-xv]

I am extremely interested in physics but as I get deeper into the field the math and concepts start to elude me. I am grateful that there are folks like Don Lincoln that can help explain the subject!

[richard]

When he overviews several theories and the result is "we just don't know" somehow it feels so satisfying. It's like he is the only person out there who really gets it, and gives it to us straight. "It's complicated" lol

[daves]

I appreciate his effort to be impartial and objective in his explanations.

[garyc]

Thank you Don, for the time, effort and dedication to the topic you provide us all with in these vids.

[gregturpin]

I only discovered Dr. Lincoln about six months ago. Still working my way through his amazing library. Please keep up the great work, sir! You are greatly appreciated!

[Raziel_SSJ]

Thanks for this video. Being careful when asserting something and not beeing too sure of us is often overlooked.

[helpmechangetheworld]

I very much appreciate your sturdy attitude, not jumping to conclusions until we get actual results. A lot of science communicators, and science enthusiasts tend to forget the core principles of science somedays...

[stephenburrow]

Another outstanding video. Great presentation of why this issue is more complicated than it may seem at first.

[chadbailey]

I love how you describe scientific debates. You are an A+ educator!!!

[anthonyhargis]

Always educational and hard to turn away from. Outstanding Professor!

[frankmalenfant]

I had that question in mind for a few months now. Thank you for that enlightening explanation.

[paullukens]

I am a retired Biology Teacher. Believe it or not, I have watched DOZENS of YouTube physics videos... just trying to understand one tiny little bit of what 'gravity' is. Dr. Don... after watching your video I GET IT NOW!!! Woohoo. Great explanation. It only took me 42 YEARS (!) of trying, to finally understand. A million thanks!!! (I hope you don't let rude viewers change your teaching style. It is OH SO EASY to criticize using this 'Comments' format. Some people watch, just looking to cause grief.)

[horse._]

I am in my sophomore year of highschool and Im thinking i want to be an astrophysicist. Even for me, someone with little physics know-how, this was extremely understandable. I applaud you for your ability to explain so well in such a simple manner.

[sapelesteve]

All that I can say is "May The Force Be With You Dr. Don"! 🤔🤔👍👍

[VardaMusic]

It’s wonderful how much we have yet to understand- and the way you highlighted that here helps the creative thoughts flow so that we can reach those higher levels of understanding with less road blocks caused by closing our minds to even what we can’t conceive of yet. So many things in astrophysics in particular hinge on theories, not definite fact, and it seems to me some videos I’ve watched forget to remind the watcher of that. Thank you for the thought you put into this!

[toughenupfluffy]

3:37. Of all the videos and textbooks I've ever seen, this is the first to portray the bending of spacetime in 3 dimensions. Well done!

[RichardWilkin]

Just today I was thinking about the subjectivity of information. For example, if I was in an audience listening to someone speaking Cantonese, to me it would be data (I’m getting audible signals, but they don’t mean much to me), but to someone else who speaks it, it would be information. That could be another example of how the conceptual framework used affects the communication requirements.