Practical Innovations that changed the world!

1. Faraday's discovery of induced current from changing magnetic flux which runs our economy now. Think of a world without electricity - no light, no tv, no laptop and no internet!
2. Graham Bell's invention of Telephone - It totally changed the way we communicate. Precursor to this is Telegram and Cellphone is successor.
3. James Watt's Steam Engine and Trains - it changed the way people move.
4. Wright brothers' invention of air planes - of course, it also changed the way we move.
5. Computers - it changed the way people do work, buy, entertain. All kinds of reservations, shopping and great scientific endeavours like 'curiosity'.
6. Ability to make controlled fire. It changed the way we eat or build things.
7. Agriculture - It again changed the way we eat.
8. Ability to forge metals.
9. Counting in base 10.

 Did I miss something more important?

What is Temperature?

I was thinking about what is Temperature.


What it means for something to be in particular temperature? I looked around in the net, and learned that it is simply average kinetic energy of molecules.

If something is hot, the molecules in that something is moving around or oscillating faster. In the case of metals it is electrons. If something is cold, the molecules are relatively slow.

Why do we feel hot when we touch a hot object? The molecules in the object collide pretty hard on our fingers, trying to disturb our cells which is felt by our neurons as 'hot'.

Why do we feel cold? When molecules in the air is taking away average kinetic energy from us through collisions and we lose energy [heat].

What's the use of physics?

One word answer - Electricity.
Can you think of living in a world without electricity? What we take for granted came from physics.
Although that's not the reason for physics [its for its own sake] its the utility of it.
So today's Mars exploration etc. will turn into tomorrow's 'Electricity'.