# What actually is energy?

1. Feb 28, 2017

### Abhi9826

Hey we know a general definition about Energy that it is capacity to do work...Or to do work energy is required.....But this doesn't make any sense to me..

2. Feb 28, 2017

### Staff: Mentor

I think that no-one explained that better than Feynman: http://www.feynmanlectures.caltech.edu/I_04.html

The conclusion is
I would also add that one can say that "energy" is the conserved quantity due to the fact that physical systems are invariant under time translation, see https://en.wikipedia.org/wiki/Noether's_theorem#Example_1:_Conservation_of_energy

3. Feb 28, 2017

### BvU

Hello Abhi,

Did you perform a thorough search before posting this ? What was it you specifically don't understand ? There's a lot to say about energy, but others need assistance too.

4. Feb 28, 2017

### Staff: Mentor

What part of the definition is confusing to you? Do you have trouble with what "work" means or what "capacity" means?

5. Feb 28, 2017

### Abhi9826

Actually I didn't understand what the Energy is...In general we say sound , radiation ,chemical bonds ,mass or any thing which is under any field (magnetic or electronic ) is Energy or posses energy...So we relating energy to everything....

6. Feb 28, 2017

### Abhi9826

I have been thinking about this since a long time but I didn't got any suitable meaning to me...

7. Feb 28, 2017

### ZapperZ

Staff Emeritus
You need to step back and see if you actually understood what you are asking. For example, ask yourself "What is an apple?" and see if you can answer this. Then look at the answer you gave yourself on something that you think you know.

You will find that your answer will include descriptions such as "It is a fruit" (which is really a classification of the object), "It can be eaten", "It looks like this" (accompanied by a number of pictures of different types of apples), "It tastes like..... an apple" (which assume that others understand and have a reference point to what an apple should taste like), etc... etc.

In other words, all you can give are ...... drum roll..... DESCRIPTIONS of the PROPERTIES of an apple.

What an object is is nothing more than a series of its properties and descriptions. So what you ask "What is X?", we have no other abilities than to describe to you the properties and characteristics of X.

Unfortunately, based on how you asked about energy in this thread, it appears as if you are seeking something beyond that, and frankly, something that doesn't really exist based on how we understand things. Asking "What is energy?" will inevitably results in us giving you all the properties and description of energy based on the physics of it. It is not just one description. It is a series of description, just like the apple.

We have had numerous threads in this forum asking for the same thing. You never responded to the question on if you've done any search.

Zz.

8. Feb 28, 2017

### Abhi9826

Sorry I have just joined this forum...

9. Feb 28, 2017

### ZapperZ

Staff Emeritus
Unfortunately, this doesn't tell me if you've understood what you read, or why "just joined" has anything to do with this discussion.

Zz.

10. Feb 28, 2017

### BvU

No need to apologize. But you have to help us a little bit by clarifying what we can do to provide you with a useful answer.