where does light from a torch go?

[origin]

Guys, can you give me a list of unknowns please?

I'm thinking it might start with (but correct me if I'm wrong):

Why is the speed of light always perceived as a constant?
What is dark matter/energy and baryonic matter?
What is mass and why does it have mass?
What actually causes gravity, other than presence of mass?
Why is there inertia?
What is inside a black hole?
Where did the universe come from and where will it end up?
Various quantum mysteries?

I know we can describe and predict but I'm asking whether we actually understand and explain? What are the current big unknowns that get scientists scratching their heads? Thanks.

Why do you guys always ask questions that are so easily answered with a simple internet search?

Questions.

I do not know why in the world this would interest you. If you would like to help solve these mysteries then get a 4 year college degree in physics graduating in the top 25% of the class. Then you can enroll in a doctorial program and get PhD. If you are very smart and very lucky you may have some part in solving one of these mysteries.

If physics interests you stay in school and concentrate on math and science. If you are out of school take some math and physics courses from your local Community College.

 

[origin]

origin - thanks for your link it was a good read but I kind of knew most of it in any case.

The sort of thing I get hooked up on is statements like this from the link:

"Scientists today accept the existence of photons and their weird wave-particle behaviour."

What that means is the idea of wave-particle duality is outside of our normal experiences so we have to accept what the evidence is telling us even if it is counter intuitive to our everyday macro environment.

It's almost like they "accept" because there is no other explanation currently available.

The evidence is overwhelming that this is the best explanation - so in fact there is no other good explanation available. Some day there may be.

I don't like simply "accepting" something and that's why I'm digging in the areas of mystery.

Then you are in a bad way, becasue you clearly do not have the expertise to understand the physics on any other level. You would need copious amounts of math and physics to move beyond the 'just accepting level'.

 

[dav57]

Still thinking about this and I would like to know something.

I would like to understand the behaviour of a mirror (or indeed a half-mirror) when it reflects a light wave. Does it behave as an observer/receiver by taking on board the energy and then emitting a corresponding, equal amount of energy? Or does the wave energy simply bounce off? Thanks.

 

[origin]

Still thinking about this and I would like to know something.

I would like to understand the behaviour of a mirror (or indeed a half-mirror) when it reflects a light wave. Does it behave as an observer/receiver by taking on board the energy and then emitting a corresponding, equal amount of energy? Or does the wave energy simply bounce off? Thanks.

here and here

 

[dav57]

Ok, thanks, so a reflector/mirror - even a half-mirror - is a receiver/observer of some sort because it absorbs/interferes with some of the energy obtained from the original source before propagating elsewhere to be "measured".