# How to explain Physics

Hello;
This is my first post, and I am not sure I am posting in the right forum, if not, please move my post and I apologize.
Ok here goes:
Bear with me as I am not a professional; I never learned physics, my work doesn't involve physics (well, it does a little as I code video games and sometimes I code physics engines, but that's really superficial). But I am interested since I was little, I read a lot about it, I've read Hawking, Einstein, Reeves numerous blogs and forums posts, and I regularly buy scientific magazines. After reading Hawking's most popular books something like five times each, I'd even I have a fair grasp of physics concepts.
My question is: how do you explain relativity and quantum physics to people that are not used to the concepts?
When I am with friends and family and we are watching a movie that talks about time travel, or speed of light, or sometimes just in casual conversation, there is always a point where I have to explain why time is just another dimension, and should not be considered like a current flowing in one direction, how it is relative, how there are more than 3 dimensions, etc.
I use all the "easy" visualizations, as "consider how a video-game character in a 2D world would relate to 3D, this is how we relate to 4D", and the large ball on a stretched sheet of paper that deforms it, and the cat in the box, etc.
Usually people, after struggling with the ideas a little (and I can't really blame them as to be honest I still struggle with most of those ideas), finally understand the point.
Where I really get stuck is the next part, when they tell me "ok, it's very nice, it's sci-fi, it's mad scientists sitting in their labs and blabbering whatever". Then I tell them that most of these ideas have verified empirically, and some of them have very real applications in our world. But I am unable to convince them as I do not know myself what are the experiences and the outcomes of those theories.
So, to sum it up, I have three questions:
1) Is there any resource on the net that explains in layman's terms what relativity and/or quantum physics are?
2) How do scientists know what they are talking about? I mean, if a quark is smaller than an atom and can't be observed, how are they observing it? I am always asked that question and I have no idea of how to answer it.
3) Can you give me some example of down-to-earth, real, applications of those theories, or at least some way to convince people that what I am talking about is not just stupid aimless thoughts?
Or, more easily:
How do you about not only explaining, but convincing people that, say, time is relative?
I realize it's a lot of questions for one post so maybe just some links or pointers will be enough.
I have also questions of my own about concepts I have troubles to grasp, but that will be for later posts.
Sorry for my English!

Hi there,

To answer your question as properly as possible, physics and science in general is (in my opinion) not suppose to be complicated. Ok, there are a few theories that require alot mathematics to understand, but im general you can get the big picture with very simple explanation. I mean, the best scientist (like Einstein and Faraday) ever explained their theories with little cars and trains.

To come to your specific questions:
Is there any resource on the net that explains in layman's terms what relativity and/or quantum physics are?
Einstein explained his special relativity theory using a train as an example. You can look for reference on the web.

if a quark is smaller than an atom and can't be observed, how are they observing it?
Be careful with this statement. Just because a particle cannot be seems with a microscope, does mean that it can't be observed. The same stands for astronomical effects, that cannot be measured on Earth.

Therefore, in these cases, you need to have a system for which you purposely disturb and looking at the effect of the disturbance. This disturbance is done by the experimental scientist. Their results are then compared to the results obtained from the theorist. If both match (quite well), then we can be pretty sure that the phenomenon is understood. For the quark, we suppose that there are 6 different types of quarks. Only two of them constitute the proton and the neutron. But, by disturbing let's say the proton, with different type of radiation, or by collision with other particles, effects can be measured and quarks can be "observe".

an you give me some example of down-to-earth, real, applications of those theories
Sorry for that, but some of the theories like particle physics and general relativity have no effect in the "real life".

In the history, up to about 100 years ago, discoveries were made, and then science tried to explained them. Nowadays, science explains different theories and tries to find use for them.

As for convincing your friends, you would have to get different examples for each and every theory that you are explaining.

Hope I helped a bit.

Cheers