Was Einstein 'wrong'? | Testing new theories of gravity

00:00 - Video Introduction
01:00 - A brief history of gravity
01:59 - Einstein's theory of General Relativity
06:21 - Problems in Cosmology and why we care
08:46 - How do we come up with new theories of gravity?
09:23 - Starting with an observation e.g. MOND
12:20 - Adding an extra field/force
14:12 - Adding extra dimensions e.g. string theory
16:25 - Conclusions
19:09 - Bloopers

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👩🏽‍💻 Dr Becky Smethurst is an astrophysicist researching galaxies and supermassive black holes at Christ Church at the University of Oxford.

[lorenh]

Why is the force that grabs us not called grabity?

[AllelujaYourMother]

i love u for mentioning that 2d representations of gravity is not ideal <3

[sbeckmesser]

Like so many of her videos, this one is extremely well argued and structured. So easy to go from beginning to the end, building knowledge along the way.

[andrewpotapenkoff]

I wish Dr. Becky was my physics teacher at school.
Very inspiring, thank you!

[davidlillo]

I love it when you talk about the history and what people have tried to do. To really bring together just how hard it is to solve the great questions and the imagination scientists have to have to even think about questions themselves.

[paulgildan]

One of the main differences between Newton's treatment of gravity and that of Einstein's is really quite simple to understand. Newton's treatment of gravity included no provision for "travel time delay" of the effects of gravity changes, and Einstein's does. In Einstein's treatment, and as measured recently for gravity waves, gravity evidently travels at the same c-limit speed as that of light. This means that any mass located far enough away from another mass that attracts it, each responds to the other mass when it was at an earlier time and often a quite different spatial location. When their
separation distance is great enough, as for stars and galaxies, the travel time and its effects can be quite significant. A good analogy for understanding is to think of a batter who can see the ball only for the first few feet after it leaves the pitcher's hand. What happens if the ball's path curves horizontally (the infamous "curve-ball")?

[mina]

First Up and Atom in garden overalls…
Now Dr. Becky…
What is going on‽

[victoriay]

You’re amazing! Thank you for making these topics so accessible for us lay people that love it 😍

[TheHispanicHombre]

I definitely love hearing her explain things. I enjoy all her videos and enthusiasm. Just got her book, "Space at the Speed of Light" in the mail.

[Tinman_]

I'm kind of a magnet freak most of my life and as often as I hear the relationship between magnetism and gravity (are/maybe related) it's perplexing to me that we've not defined the correlation of the two and be able to use both as a means of propulsion for the space industry and planetary exploration. Thank you, Dr. Becky, for your continued scientific research. :)

[yaka]

Hi and Thankyou for the post... i was wondering if you have come across Nikola Tesla's Dynamic Theory of Gravity and if this fits with the current thinking around mond. My brain isnt good enough to work this out other than at a very high level. however i would trust your opinion.
many thanks

[Hisham_HMA]

i don't think anyone completely understands General relativity or black holes or galaxies, dark matter, too many variables, too many puzzle pieces, we have to understand what is Gravity first then we can compare it and study its effect on other objects by experiments not just math
we have to take it step by step, physicists today are like a mother freaking out when the electricity is off, "what is going on?, how are we going to live?, what about food in the fridge? what about our kids? how are we going to eat? how am i gonna make a cake in the dark even though i don't know how to make cake ( talking about things we don't understand, dark matter, black holes, etc..))

[karlesmcquade]

I would like to have a strong enough command of tensor calculus to appreciate Einstein's Field Equations. I'm willing to put in the hours of work over months (or years, if necessary). However, I don't know how to go about studying tensor calculus outside of a university setting, (which isn't an option right now anyway). Do you have any advice? I've been wanting to study tensor calculus for years!

[freddangbg]

Great to watch intelligent and educated young women in physics on YouTube. We need more of that.

[Gamefreak]

1st video of yours that I've seen. I'll be watching more. Informative and easily enough understood. Keep up the good work. Thanks :)

[Svenmpa]

Your videos are brilliant, and more so your delivery of the information. I've never heard anyone talk like you do, with your fast paced phrases, but more so the slowing down with certain important parts. It is such a pleasure to listen to.

[anitabressanthefelinealpha]

Congratulations, you are really good at this! Your videos are always interesting and you explain things very well!

[lamegoldfish]

I love the idea of 'I don't know' or even better, 'We don't know'. 😃

[sjcwoor]

String theory and 10D seems to be a mathematical "bodge" to just make our current understanding "fit" even though we could never measure and prove it, since it's not observable.

[kjevers]

So Dr. Becky, after all that explanation Einstein is still the best we have after 115 years of research. This make me wonder with dark matter and energy, if we are missing a dimension that we can't detect quite yet. We see the affect, but not precipitator. Thanks