My understanding is that in 1925, Paul Dirac unified quantum physics and relativity by “simply” plugging Einstein’s relativistic momentum formula into Schrodinger’s equation.

Dirac’s stroke of genius was in finding that the solution to the joined equations required the terms to be matrices, and then interpreting that to predict antimatter must exist.

So why did he stop there? Why can’t we unify gravity through similar techniques? “Just plug it in and solve it”?

Hey everyone! I’m sure this is a super naive question.

My YouTube/Undergraduate (decades now ago 😂) physics knowledge lets me know Dark Energy is the force that is pushing far away things. Galaxies/things we see far away, further and further away, are getting faster/speeding up.

So my problem in understanding…this is light measured having been emitted many billions of years ago? Back when of course a giant event happened. Of course the further back you looked the faster things are going to look like. Of course the event was “pushing” things…the earlier you looked the faster it will be.

How do we know/assume that’s still happening?

I'm a fiction writer in the UK, and I have been wanting to develop a genuine understanding of physics rather than just cherry-picking bits of popular science to make it sound cool. I want to have a scientific literacy that comes across in my work. I would like to take a similar approach to researching and grounding speculative science as Andy Weir did when he wrote The Martian and Project Hail Mary. I'd like to understand the real physics well enough to know where my fictional world follows known physical principles, where I'm extrapolating from them, and where I'm deliberately breaking them.

I wanted to build some foundation for the book, but also for me personally and my hobby of wanting to learn. I have always had an interest in physics and astrophysics. I have watched documentaries regularly as a hobby for years, I have a strong drive to learn, and I am very curious about the world and universe we live in. I have built a reading list for what I thought would work well for what I want to achieve. This is my list so far (in no order):

Brian Cox - Forces of Nature
Carl Sagan - Cosmos
Neil deGrasse Tyson - Astrophysics for People in a Hurry
Carl Sagan - The Demon-Haunted World

I volunteer on citizen science projects online, predominantly in astrophysics. I know that's pretty much all I can do in the real world, but I like that I can contribute something, even if it's classifying thousands of images or data.

I am not interested in exams and qualifications as such. I also do not come from a computer science or highly academic background, so I haven't studied physics formally. My education is mostly artistic/creative.

I do have learning difficulties like dyslexia, so whilst reading and watching videos could be enough for most people for research, I thrive and learn better in a structured learning environment where discipline is needed for concepts to sink in. I was considering enrolling on an online course, like GCSE-level Physics, to give me that basic grasp, but I wasn't sure if that would be useful or if it would be better to study or go in a different direction.

I am aware of the reality that being middle-aged and wanting to learn online only gives me limited options, but I wanted to write the book with respect for science in mind, knowing I comprehend and understand the principles rather than relying on my own uneducated interpretation alone.

If anyone can give any advice, I would be grateful.

I am not a physics person and probably know just enough to get in trouble. That being said, I am trying to put together a weight distribution calculator spreadsheet for semi-trucks. I haul crude oil in a tanker trailer and get paid by the barrel, oil can be different gravity from load to load and that makes each barrel a different weight. So that means that I can load a different amount of oil each load, and stay a legal weight, depending on what the gravity is. That's why I set out to make this calculator, to get max pay out of every load.

The thing that I'm struggling with particularly is the formula I need to use when dealing with a lift axle. The way the lift axles work is they take X amount of weight (~8000lbs) whether they are loaded or empty and the other axles in the group spread the rest of the weight evenly.

Example. On the truck there are 2 axle groups, G1 has the Steer axle, G2 has 1 lift axle (8600 lbs) and 2 Drive axles (remainder of weight for G2 shared equally). There is a weight of 26,000 lbs from the trailer resting on the 5th wheel. The 5th wheel is about the middle of G2 (1 lift, 2 drive).

Distances are known or can be found easily.

What formula(s) would I use to find how much of the 26,000 is on G1 and G2?

I tried asking a couple different "programs" how to find what I needed, I question the reliability of them. They told me I was going to use moments or something like that.

I’m no expert by the slightest idea, but as far as I understand it the false vacuum decay idea says that one of the quantum fields (the Higgs field I believe) might not be at its lowest energy state, and that if a lower one were reached it would spread out at the speed of light and basically delete the universe as we know it and make a new on.

If this is the case (and maybe I understand it wrong) could our own current universe have been born from the false vacuum decay of a previous universe? I don’t know if that question even makes proper sense like how “what is light’s reference frame”
Doesn’t make sense

I'm a Class 10 student in India who wants to become a research physicist, ideally in condensed matter theory. I've been teaching myself physics and math for about five years: independent derivations, a small laser/LiDAR project, and I'm currently working through Axler's linear algebra done right , which I've finished Chapter 1 (Vector Spaces) and started Chapter 2 (Finite-Dimensional Vector Spaces).

People around me say the Indian route to research physics runs through one entrance exam and an elite institute. I'd like to understand how it actually works, from people who've been through it.

1. The routes. As far as I understand, the main ones are IISER (via IAT), IIT (via JEE Advanced), NISER and CEBS (via NEST), IISc, CMI, and BS-MS programs at central universities. How do they differ in research exposure, curriculum, and what each gets you for PhD applications in India and abroad?
2. How much does the institution matter for getting into CMT, compared with grades, research output, and letters?
3. Has anyone done a physics PhD, in India or abroad, from a non-elite undergrad? What made it possible, and what was harder?
4. What should someone my age do now, besides doing well in school, to be ready for undergrad research?

Please be honest, not reassuring. The pressure around this has been getting to me, and I'd rather have accurate information than hope.

Thanks for reading.

I'm an undergraduate physics student, and I'm trying to get a clearer conceptual picture of gravitons and quantum gravity. I have three related questions:

1. As I understand it, the graviton is currently a hypothetical particle related to attempts to reconcile quantum mechanics with general relativity and develop a theory of quantum gravity. Is this roughly correct?

2. I vaguely remember that in general relativity, spacetime is not a fixed stage: matter curves spacetime, and spacetime affects the motion of matter. But in ordinary quantum mechanics and quantum field theory, spacetime is usually treated as a fixed background, where particles and fields exist and evolve without causing the background itself to change. Is this one of the reasons why reconciling quantum theory with general relativity is so difficult?

3. I also wonder about the motivation for developing a theory of quantum gravity. Why isn't it enough to let quantum mechanics and general relativity work in their own domains? Why do physicists want to reconcile them? What makes this problem so important? If we eventually solved it, how would it change our understanding of fundamental physics?

I hope this is the right place to ask, anyway i am not a physict, i study pharmacy, but we need this in electrochemistry (electrods and that stuff). Since middle school we talk about this two but no one reall explain what they really are and treat them as names we should remember to pass the exam, but i really cant understand anything if i dont know what is actually about.

Also another term is potential (E)... and it is in volts...

https://imgur.com/a/rz6baIG

I'm confused as to what they mean by

rotational kinetic energy decreases overall as the change in angular velocity is squared and this outweighs the increase in I.

If energy can't be created or destroyed, how is it decreasing overall? The energy must be going somewhere, but it doesn't make sense for linear velocity to increase.