The Naked Scientists

The Naked Scientists Forum

Author Topic: What is energy?  (Read 4621 times)

Offline bahesbesdk

  • Jr. Member
  • **
  • Posts: 10
    • View Profile
What is energy?
« on: 03/04/2010 11:02:47 »
1-What is the energy?

2-Can the energy exist without presence of the matter ?

3- Can the matter(or energy) exist without presence of its laws ?

regards




Mod edit - subject formatted as a question.  Please do this to help keep the forum tidy and easy to navigate.  Thanks.
« Last Edit: 03/04/2010 15:29:45 by BenV »


 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
Re: What is energy?
« Reply #1 on: 03/04/2010 12:39:09 »
1-What is the energy?
The ability to make work.

Quote
2-Can the energy exist without presence of the matter ?
Yes, for example an impulse of light has energy but no mass and it can exist in void space without the presence of matter.

Quote
3- Can the matter(or energy) exist without presence of its laws ?
What do you mean?
 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
What is energy?
« Reply #2 on: 03/04/2010 18:45:17 »
Energy is a way of describing the fundamental content of the universe.  Matter is just one way of creating trapped energy that can be stationary.  Electromagnetic energy is a form of free enegy that must stay on the move at the velocity of light. Gravitational energy is a residual distortion of space time (that is probably itself a form of structured energy) that is caused by trapping energy to form matter.

energy can exist without matter.

Matter and energy cannot exist without its laws.  At first sight this is rather a silly question but it is probably a very significant philosphical question.  At the fundamental level, quantum mechanics, which describes most precisely how our universe works can be stated that everything that is possible, according to the physical laws, happens, with the relative probability of its happening as defined by these laws. 

Now at the most fundamental level absolutely everything regardless of any physical laws may happen BUT any universe can only exist if its laws are consistent in some way that allows it to form structures that last for a significant length of time.  Without this everything would be so transitory that nothing could ever develop or be observed  (irrespective of life like us) 

The fact that we exist and can observe our universe implies that our universe must be particularly well ordered and stable and therefore obey its physical laws.

Many areas of fantasy writing create universes in which the physical laws are bent and modified such universes could not be stable or exist properly.  They are just interesting fantasy and do not represent anything that we might develop in the future through the application of science.

Notably, for example, faster than light drives mean that the universe does not obey causality and effects can happen before the events that cause them if this was to happen the whole universe would fall apart!
« Last Edit: 03/04/2010 18:53:49 by Soul Surfer »
 

Offline SammySchwartz

  • First timers
  • *
  • Posts: 7
    • View Profile
What is energy?
« Reply #3 on: 06/04/2010 14:01:50 »
Thanks for describe about energy. I like the way of your explanation. It is very nice way of explanation.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
What is energy?
« Reply #4 on: 11/04/2010 19:40:59 »
Energy seems to be a description of 'work done'. when some work is done by your car f.ex we say that it have used a certain amount of energy. That 'energy' is an abstract description of something we can't put our finger on. We know that it exist and thermodynamics f.ex use the idea of 'work' and 'work done' as a definition of what it can be seen as.

Our universe is expected, some time in the future, to have only 'work done' left in it. That means that all 'energy', or 'work' possible, will have been used up through the universes diverse transformations of radiation and matter. Energy is that strange 'force' that we use in those transformations, chemical or other, to make things happen.

It's a immaterial substance making things happen, or if you like, an abstract description. Its what disappears when 'work is done' and although nothing really disappears from our universe due to those transformations the energy becomes unusable to us after enough transformations of it. The idea there is that the energy finally will become stored in such states that we can't make any easy use of it, like heat.

"In nature, transformations of energy can be fundamentally classed into two kinds: those that are thermodynamically reversible, and those that are thermodynamically irreversible. A reversible process in thermodynamics is one in which no energy is dissipated (spread) into empty energy states available in a volume, from which it cannot be recovered into more concentrated forms (fewer quantum states), without degradation of even more energy.

A reversible process is one in which this sort of dissipation does not happen. For example, conversion of energy from one type of potential field to another, is reversible, as in the pendulum system described above. In processes where heat is generated, quantum states of lower energy, present as possible exitations in fields between atoms, act as a reservoir for part of the energy, from which it cannot be recovered, in order to be converted with 100% efficiency into other forms of energy.

In this case, the energy must partly stay as heat, and cannot be completely recovered as usable energy, except at the price of an increase in some other kind of heat-like increase in disorder in quantum states, in the universe (such as an expansion of matter, or a randomization in a crystal).

As the universe evolves in time, more and more of its energy becomes trapped in irreversible states (i.e., as heat or other kinds of increases in disorder). This has been referred to as the inevitable thermodynamic heat death of the universe. In this heat death the energy of the universe does not change, but the fraction of energy which is available to do produce work through a heat engine, or be transformed to other usable forms of energy (through the use of generators attached to heat engines), grows less and less."

Other than that I don't know what it is. It's a remarkable idea :)
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
What is energy?
« Reply #5 on: 16/04/2010 13:07:37 »
"3- Can the matter(or energy) exist without presence of its laws ?"

Are you wondering what if we took away whatever it was making matter matter, it still would exist in some form? Maybe? Energy and matter are not interchangeable's though. Mass and energy is, but matter will leave a 'restpart', as I understands it, when transformed into energy?
Weird, ain't it :)
 

Offline Pmb

  • Neilep Level Member
  • ******
  • Posts: 1838
  • Physicist
    • View Profile
    • New England Science Constortium
What is energy?
« Reply #6 on: 17/04/2010 14:06:29 »
Quote from: bahesbesdk
1-What is the energy?
Nobody knows. I created a web page which explains the idea of energy. See
http://home.comcast.net/~peter.m.brown/mech/what_is_energy.htm
Quote from: bahesbesdk
2-Can the energy exist without presence of the matter ?
This is one of those instances where the answer to your question depends on how you define something and there are different definitions in current use.

I myself would say no since, in his 1915 paper on General Relativity, Einstein defined the term "matter" such that where there is energy there is matter. However physicists today disagree with how the terms "energy", "mass and "matter" are defined. lightarrow used the term "mass" to be synonymous with the term "mass" where by "mass" he means "proper mass" (aka "rest mass"). However I know of a text where the author uses the term "mass" to mean proper mass but uses the term in a way that is consistent with Einstein. In fact he explains this in the physics text he wrote explaining that even a static electric and magnetic field has mass.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
What is energy?
« Reply #7 on: 19/04/2010 16:55:42 »
Read this, I really like it. It seems quite clear, and even the math is sufficiently explained. The Equivalence of Mass and Energy.

It's actually the best I've read on that subject.
==

I liked your link too Pmb :)
A nice description of energy.
« Last Edit: 19/04/2010 16:59:50 by yor_on »
 

The Naked Scientists Forum

What is energy?
« Reply #7 on: 19/04/2010 16:55:42 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums