Recent content by rc1

The Interval is invariant under special relativity. ##s^2= x^2+y^2+z^2-t^2##

I think Einstein thought about this "Gedanken experiment" as "sitting on a light beam" in his development of Special Relativity. Try this site- https://sites.pitt.edu/~jdnorton/Goodies/Chasing_the_light/

Evaporative cooling is less effective in the tropics due to the high humidity, so spraying water may have limited effectiveness. It may be fine in the south of France though.

The active vs passive heating/cooling argument- both are useful depending on the circumstances, often active techniques are more effective at the cost of some maintenance and complexity and money. Yes I agree that knowing where the heating is coming from may not help you fix it, it might be...

You can get thermal camera's that can tell you where the heat is coming from but they're a little pricey. Maybe someone provides a service but that's probably also pricey. You could use a non-contact thermometer, much cheaper, to map out the temperature distributions at different times and...

With some boats fitting solar powered electric motors with large solar roofs they might absorb a lot of ir energy. If these roofs can be thermally isolated it could be better.

From memory there is the wavefunction and what it interacts with - the Hamiltonian- like the infinite well problem. The wells structure doesn't change in time but it does with change in x- so the H is time independent. Not sure about relativity here.

I've seen articles about laser welding pencils used on the shuttle. Could be used for metal 3d printing but thermite gell is probably better in many use cases. Uses fibre and q-switching from memory. Divergence seems to be the issue for offence- for defence the range could work in some cases but...

Yes sorry that's what I meant. Thanks Ibix for the correction. Also Murray Gell- Mann has a TED Talk on why physics is beautiful at different scales because it's similar.

You could probably argue that spacetime is approximately flat on the scale of the Solar System.

Angelika10 said- "Therefore, the field of the galactic center is big at our place!"- Newton's 1st Law (of linear motion)- Speed is not dependent on force. In this case the motion is rotational motion w= v/r. Centripetal Force = mv^2/r and this is proportional (equal) to the field strength...

Dark Matter is an attempt to explain why Galaxies appear to have more mass than the light in the Galaxy indicates. Dark Energy is another thing- and appears to be relate to the expansion of the universe- some explanations involve exotic matter (negative mass and energy) from memory.

Some of the questions Angelika is asking seem to be on the edge of physics- things that physicists are struggling with- that no one knows the answer to- the question about what is the fundamental reality of "our" universe. The approach that seem to me to have the most potential is cellular...

There's a very good simplified non robust (8 step) derivation of the EFE on YouTube from Stanford from memory. Wheeler said "mass tells space how to bend and space tells mass how to move" (from memory). Basically my understanding is- Einstein asked the question "what if distortion in space time...

Yes after commenting I realized the publish date. Thanks Twigg for the explanation. I couldn't follow the pdf- but your maths looks pretty fine- I'll have to look further at the background. Not sure how you slotted the transition probability into the equation- I'll have to review it again...