Register to reply

So what is ENERGY?

by basePARTICLE
Tags: energy
Share this thread:
basePARTICLE
#1
Jan16-08, 01:33 PM
P: 86
As an introduction to this physics forum, let me begin by asking:

What is energy?

Is Energy something tangible or is Energy only apparent when certain base characteristics belonging to the topological composition of our universe interact or you may have another idea in mind which can play out in the real world?


Yes welcome to our universe
Phys.Org News Partner Physics news on Phys.org
New complex oxides could advance memory devices
Nature's designs inspire research into new light-based technologies
UCI team is first to capture motion of single molecule in real time
chroot
#2
Jan16-08, 06:51 PM
Emeritus
Sci Advisor
PF Gold
chroot's Avatar
P: 10,427
Your post is mostly word salad. You're using words like "topology" incorrectly, for example.

Energy is just a number we assign to a system to quantify its ability to perform work. No more, no less.

- Warren
jdg812
#3
Jan16-08, 08:41 PM
P: 91
Quote Quote by chroot View Post
No more, no less.
Sometime, the energy is MORE than ability to perform work. For example, if thermal energy is Q, the ability to perform work is only Q*(T2 -T1)/T2

lilrex
#4
Jan16-08, 09:00 PM
P: 64
So what is ENERGY?

wordsalad or not, the ability to perform work is a simplified explanation to an observation that we make on a regular basis. doing things like increasing the mass of an object containing kenetic energy. manufacturing matter from apperantly nothing... bending the fabric of space...

the question I often ponder is how does the energy given to a base ball in the form of kenetic energy be a direct realitive to the material of the baseball.

of course my cheese may have slipped off my cracker with this post!
Claude Bile
#5
Jan16-08, 09:17 PM
Sci Advisor
P: 1,477
Energy is DEFINED as "the ability to do work".

The ability to do work is in turn determined by the current state of the system in question. Gravitational PE depends on the distance from a mass (or masses). KE depends on velocity, etc.

There is nothing in our current model that suggests energy consists of some "stuff" which seems to be an idea that persists in this thread.

Claude.
HallsofIvy
#6
Jan16-08, 09:29 PM
Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,683
"topological composition of our universe interact"?? I've taken topology and I can't make heads or tales out of that. I can't even determine whether "interact" here is supposed to be a verb or a noun. I would think of "interact" as a verb, but that doesn't make grammatical sense here.

Basically, "energy" is a bookkeeping device. In basic kinematics, with simple "perfectly elastic" collisions, it was recognised that a particular combination of variables, (1/3)mv2, "kinetic energy", remained the same and so "conservation of energy" became a good rule for solving such problems. Add changes in height and you had to add "potential energy" to "balance" the equations. Add motion with or against a non-conservative force and you had to add "work". Put in friction and you had to add heat as a type of "energy". The history of mechanics has been one of creating new kinds of "energy" in order to keep "conservation of energy" true.
rbj
#7
Jan16-08, 09:57 PM
P: 2,251
Quote Quote by HallsofIvy View Post
"topological composition of our universe interact"?? I've taken topology and I can't make heads or tales out of that.
that's because your last name isn't Bogdanov or Bogdanoff and you do not host a French pop-physics (or pseudo-physics) television show. if you were thus qualified, Halls, you would know what that means.
Andy Resnick
#8
Jan17-08, 07:49 AM
Sci Advisor
P: 5,543
To be fair, the OP did ask a question central to physics.

Energy is a property of objects and systems of objects. There are various forms of energy (e.g. mechanical, thermodynamic, informational), and they can interconvert from one form to another. We know some properties of energy- the total amount is conserved in a closed system, we can interconvert one form of energy to another in controlled experimental conditions, and we can quantify how much energy a particular object/system has.

As for what energy 'is', you could just as easily as "What is 'red'? The fact that a simple answer doesn;t exist does not make the concept any less useful.
jdg812
#9
Jan17-08, 08:16 AM
P: 91
Quote Quote by HallsofIvy View Post
Basically, "energy" is a bookkeeping device.
...
The history of mechanics has been one of creating new kinds of "energy" in order to keep "conservation of energy" true.
Yes, absolutely!

Actually, we have several such bookkeeping devices, like momentum, angular momentum, mass (in nonrelativistic case) etc.

Actually, I am not sure that number of such devices is finite. Because some nonlinear equations have INFINITE number of independent integrals of motion. The first three of them are usually associated with mass, momentum and energy of the system. The rest of them are terra incognito.
vanesch
#10
Jan17-08, 08:56 AM
Emeritus
Sci Advisor
PF Gold
P: 6,236
Quote Quote by HallsofIvy View Post
I've taken topology and I can't make heads or tales out of that. I can't even determine whether "interact" here is supposed to be a verb or a noun. I would think of "interact" as a verb, but that doesn't make grammatical sense here.
Mmm, I thought that it did make grammatical (if not semantical) sense, and is, as such, a qualified, syntactically correct Bogdanov statement.

"Is Energy something tangible or is Energy only apparent when certain base characteristics belonging to the topological composition of our universe interact or you may have another idea in mind which can play out in the real world?"

is, as far as I understand, a question phrase composed of 3 sub-statements on the same level:
"Is Energy something tangible"

OR

"is Energy only apparent when certain base characteristics belonging to the topological composition of our universe interact"

OR

"you may have another idea in mind which can play out in the real world?"

although what is strange is that the last statement is an intonation question, while the other two are questions with inversion.

Let's look at:

"is Energy only apparent when certain base characteristics belonging to the topological composition of our universe interact"

which is, I would think, a correctly formulated Bogdanov phrase.

It has a main clause:
"is energy only apparent"

and a sub-clause (of time, or of condition, with "when"):
"when certain base characteristics belonging to the topological composition of our universe interact"

subject: "certain base characteristics, belonging to..."

verb: "interact"

It are hence the characteristics that have to interact.
Which characteristics ?
Those belonging to the topological composition of our universe.

It is at the time, or on the condition of those characteristics interacting, that energy is apparent, and only then.


RonL
#11
Jan17-08, 09:18 AM
PF Gold
P: 707
Can mental energy be considered here? chemical, and electrical, reactions in the head can sometime be extreme to the point of feeling exausted, both mental and physical.
I sometimes get a flood of thoughts that continue for days, every waking hour, and then i seem to sort of shut down, i'll spend time doing things that seem to require very little thought or attention. This cycle repeats on a somewhat regular basis.
ZapperZ
#12
Jan17-08, 09:21 AM
Emeritus
Sci Advisor
PF Gold
ZapperZ's Avatar
P: 29,243
Quote Quote by RonL View Post
Can mental energy be considered here? chemical, and electrical, reactions in the head can sometime be extreme to the point of feeling exausted, both mental and physical.
I sometimes get a flood of thoughts that continue for days, every waking hour, and then i seem to sort of shut down, i'll spend time doing things that seem to require very little thought or attention. This cycle repeats on a somewhat regular basis.
This is not an issue in "mechanics", and so it is not relevant here.

Zz.
basePARTICLE
#13
Jan17-08, 11:24 AM
P: 86
Quote Quote by chroot View Post
Your post is mostly word salad. You're using words like "topology" incorrectly, for example.

Energy is just a number we assign to a system to quantify its ability to perform work. No more, no less.

- Warren
I disagree with your assessment on my usage of the word topology. Mathematically the standard model, can be incorporated into a topology that can describe simple things like atoms. This is apparent because when protons, neutrons and electrons are combined, the elements that emerge are recognized for what they are, due to the combinatorial process, which is well known. Therefore to say that our universe can be described by a topology, even if it is complex in nature is closer to the truth, than you have been willing to admit.
basePARTICLE
#14
Jan17-08, 11:35 AM
P: 86
Quote Quote by chroot View Post
Your post is mostly word salad. You're using words like "topology" incorrectly, for example.

Energy is just a number we assign to a system to quantify its ability to perform work. No more, no less.

- Warren
The fact that Energy in significant units does quantify an ability to do work, does not in any way, negate the quest for knowledge concerning what is it that causes this ability to perform work to be manifest. Mere numbers will not cut the cloth so to speak. Perhaps you will move towards the definitive technical term - force!

On another note, although I accept the definition that energy is no more, no less, an ability to perform work and can subsequently be summarized by a mere number, I submit my hesitation in regarding this as an epistemological coup d'etat.
belliott4488
#15
Jan17-08, 11:57 AM
belliott4488's Avatar
P: 666
Quote Quote by basePARTICLE View Post
I disagree with your assessment on my usage of the word topology. Mathematically the standard model, can be incorporated into a topology that can describe simple things like atoms. This is apparent because when protons, neutrons and electrons are combined, the elements that emerge are recognized for what they are, due to the combinatorial process, which is well known. Therefore to say that our universe can be described by a topology, even if it is complex in nature is closer to the truth, than you have been willing to admit.
There might well be some validity to what you're trying to say, but I think the problem is that you're using words in a way that raises some suspicion that you might have a less than complete understanding of them.

I've never heard anyone who does research in this area say "the standard model can be incorporated into a topology", much less "the universe can be described by a topology."

Spacetime, Lie Groups - yes. The SM or the entire universe - sounds iffy to me.
basePARTICLE
#16
Jan17-08, 11:58 AM
P: 86
Quote Quote by Claude Bile View Post
Energy is DEFINED as "the ability to do work".

The ability to do work is in turn determined by the current state of the system in question. Gravitational PE depends on the distance from a mass (or masses). KE depends on velocity, etc.

There is nothing in our current model that suggests energy consists of some "stuff" which seems to be an idea that persists in this thread.

Claude.
This is precisely what I am after, your suggestion that the current understanding of energy is less than precise, in light of the new Quantum Mechanics.

This definition of Energy as an ability to perform work can be dated back to Newton, if I am not mistaken, and it seems as if the current trend to walk the physics line without real epistemological support needs its proper attention.

Additionally, I have not claimed as yet anything, that suggests energy consists of some "stuff" as you so eloquently stated it. I have asked for current mental notions which support the nature of Energy, while I have stated my own notion about how I believe energy shows up in our universe. It was stated clearly, but I repeat for effect, apparent when certain base characteristics (belonging to the topological composition) of our universe interact. Some of those base characteristics are summerized by the standard model, including spin and charge.
belliott4488
#17
Jan17-08, 12:00 PM
belliott4488's Avatar
P: 666
Quote Quote by basePARTICLE View Post
The fact that Energy in significant units does quantify an ability to do work, does not in any way, negate the quest for knowledge concerning what is it that causes this ability to perform work to be manifest. Mere numbers will not cut the cloth so to speak. Perhaps you will move towards the definitive technical term - force!

On another note, although I accept the definition that energy is no more, no less, an ability to perform work and can subsequently be summarized by a mere number, I submit my hesitation in regarding this as an epistemological coup d'etat.
How's this, then: "Energy is that quantity that is conserved as a result of the invariance of Physics under time translation."? (see Noether's Theorem)
belliott4488
#18
Jan17-08, 12:07 PM
belliott4488's Avatar
P: 666
Quote Quote by basePARTICLE View Post
This is precisely what I am after, your suggestion that the current understanding of energy is less than precise, in light of the new Quantum Mechanics.

This definition of Energy as an ability to perform work can be dated back to Newton, if I am not mistaken, and it seems as if the current trend to walk the physics line without real epistemological support needs its proper attention.
We can predict measurements of energy, and our measurements agree well with those predictions. What deeper epistemological support is needed in Physics?

I think the earlier post about defining "red" is quite apt. We could go around in epistemological circles for a long time, trying to decide on how we know what "red" really is, but at the end of the day, I don't think we'll be any more able to find the red car in the parking lot.


Register to reply

Related Discussions
Solar energy heat energy light energy..... Engineering Systems & Design 2
HELP! ~ Mechanical Energy vs Potential Energy & Kinetic Energy Introductory Physics Homework 4
Mechanical Energy vs Potential Energy & Kinetic Energy Introductory Physics Homework 3
Transformation of Kinetic and Gravitational Potential Energy:Conservation of Energy. Introductory Physics Homework 9
Potential energy difference as a gate to perpetual energy transfers General Physics 21