the definition of energy

[mar_mar]

"Capacity to do work" says phisics. I thought definition was specification of "whatness" nature of the phenomenon.

I think 'Capacity to do work' describes more abstract concept and seems an answer to a question "what's energy for?"

Is energy an entity or a property?

[Genady]

Quote

In physics, energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property ...

(Energy - Wikipedia)

[mar_mar]

So, solar energy is property of the sun. And we store this property in solar battery.

[Genady]

8 minutes ago, mar_mar said:

So, solar energy is property of the sun. And we store this property in solar battery.

No. Solar energy is a property of solar radiation.

[exchemist]

41 minutes ago, mar_mar said:

"Capacity to do work" says phisics. I thought definition was specification of "whatness" nature of the phenomenon.

I think 'Capacity to do work' describes more abstract concept and seems an answer to a question "what's energy for?"

Is energy an entity or a property?

A property, of a physical system of some kind, where the "physical system" may involve matter and/or fields (EM radiation consists of oscillating fields).

(In English it is spelt "physics" by the way.)  

[studiot]

There is only one sort of energy.

Material objects and fields may posses energy by a variety of different mechanisms.

All of energy theory springs from these two facts.

Much of that theory is about transferring the energy from one body or field to another; the energy transferred may end up in a different form (ie using a different mechanism).

Most of the terminology refers to these mechanisms by which the body or field possess or transfers the energy. Solar energy, electrical energy, nuclear energy etc etc.

So when you use such terminology you need to specify not only the energy but also the mechanisms involved.

[swansont]

3 hours ago, mar_mar said:

So, solar energy is property of the sun. And we store this property in solar battery.

The sun has energy owing to its mass (mass is a form of energy), and the gravity (gravitational potential energy). It undergoes reactions which emit radiation, which also has energy. 

The term 'solar energy' merely points out the source of the energy. The radiation isn't part of the sun anymore.

 

[mar_mar]

4 hours ago, exchemist said:

A property, of a physical system of some kind, where the "physical system" may involve matter and/or fields (EM radiation consists of oscillating fields).

(In English it is spelt "physics" by the way.)  

Thank you. So, what is the nature of this property? I believe, speed is also property of an object, it describes how fast it moves. Mass describes how much matter in an object, in short.

What does describe energy as a property?

[iNow]

Note to self: Looks like a back door to reintroduce another version of the “red doesn’t exist” dumbassity 

[swansont]

20 minutes ago, mar_mar said:

Thank you. So, what is the nature of this property? I believe, speed is also property of an object, it describes how fast it moves. Mass describes how much matter in an object, in short.

What does describe energy as a property?

The nature of the property is matter of metaphysics, i.e. philosophy. Science deals with how nature behaves.

[Genady]

The main feature of this property is that it is a scalar value that is conserved.

[mar_mar]

I try to find in the nature of property of energy ability to do work.

[iNow]

17 minutes ago, mar_mar said:

I try to find in the nature of property of energy ability to do work.

Punching yourself in the face would be one such example. 

[exchemist]

1 hour ago, mar_mar said:

Thank you. So, what is the nature of this property? I believe, speed is also property of an object, it describes how fast it moves. Mass describes how much matter in an object, in short.

What does describe energy as a property?

Energy is a book-keeping, conserved quantity, with dimensions ML²/T².  Momentum is another book-keeping conserved quantity, but with dimensions ML/T. Because both are conserved properties, they are specially useful in analysing physical systems and processes.  

As for what it describes, that has already been mentioned: the capacity of a system to do work: lift a weight, light a bulb of a certain wattage for a certain time or whatever.  

[studiot]

1 hour ago, mar_mar said:

Thank you. So, what is the nature of this property? I believe, speed is also property of an object, it describes how fast it moves. Mass describes how much matter in an object, in short.

What does describe energy as a property?

 

41 minutes ago, mar_mar said:

I try to find in the nature of property of energy ability to do work.

If you are prepared to listen to the explanation and to follow it as it is developed bit by bit then I am happy to discuss your request with you.

The above are very reasonable wish to explore in more detail the short statements you have already been offered.

 

So we should start with 2 matters.

Firstly the issue of 'work'.

Do you know what 'work' is. Without a good understanding of this you will not understand the answer.

 

Secondly I said there are several ways something can have energy so we should start with the simplest, which is also the easiest to relate to 'work'.

The simplest type of energy is called Potential Energy and is the energy of configuration.

For a simple system, for example when there are only two objects involved, the 'configuration' may be as simple as the distance between them.

When that configuration changes the distance between them changes and the potential energy changes.

That potential energy is equal to the work done in the change and how we get the statement

Energy is the capacity to do work.

 

 

[MigL]

4 hours ago, iNow said:

Note to self: Looks like a back door to reintroduce another version of the “red doesn’t exist” dumbassity 

You must have gotten a lump of coal from Santa because you're still cynical and a little abrasive 😄 .
Why not consider this a learning opportunity for all ?

This property, energy,  we define as the ability to do work, is essentially a property of the configuration of the system.
Whether the system is moving gives us kinetic E and/or temperature, and its positional arrangement in any external or produced fields, gives potential E.
I would add that 'intrinsic' energy, or mass, is only a property of fundamental particles, such as electrons, quarks and neutrinos.
Most of what we normally consider 'mass' is tied up in various levels of binding energy ( molecular, atomic, nuclear and baryonic ) and is correctly identified as potential E, due to the positional configuration of the system.

One could make the stretch that even elementary particles' intrinsic mass/energy is due to the configuration of the system as it results from the coupling to the Higgs field.

Edited December 26, 2023 by MigL

[iNow]

49 minutes ago, MigL said:

You must have gotten a lump of coal from Santa

Yeah, and I told him to go punch himself in the face, too.  

 

😂 

[joigus]

For a less intuitive but more encompassing understanding of energy --if somewhat abstract-- one can't do better than this:

https://www.feynmanlectures.caltech.edu/I_04.html

Or, perhaps, one can. We have Emmy Noether to thank:

https://en.wikipedia.org/wiki/Noether's_theorem#Example_1:_Conservation_of_energy

When the mathematical dust has settled, the idea is: Energy is an abstract property of systems which they must have if 1) They can be described by a principle of least action, and 2) Physical laws cannot include time explicitly.

As we know both to be the case almost universally (cosmology being perhaps a case when things should be discussed more carefully), physical systems must have an energy.

[Genady]

Energy is just a time-like component of 4-momentum.

[exchemist]

6 hours ago, iNow said:

Note to self: Looks like a back door to reintroduce another version of the “red doesn’t exist” dumbassity 

I have similar suspicions.