[CPT ArkAngel]

In the same email from which the above quote came, Dr Baird also says: “A lot of popular writers speak sloppily in this way, but it really makes no sense”.

I found this in his blog:

“General Relativity describes how gravity is not really a direct, classical force. Rather, the effect we call gravity is simply how objects move in a spacetime that is itself curved”.

Another way to understand it is simply as I said: a curved trajectory without any net energy transferred can be seen as a straight line or a null path. The fact that the trajectory of a null path is curved mean that spacetime itself is curved... This is a uniform motion and therefore the object following this trajectory is an inertial observer. I think it helps a lot to understand it this way and it is how Einstein explained it.

My own point of view of space and time differs from the standard point of view concerning the basic ingredients. In my theory, there is no space, only a basic length (the Planck length). Space is a product of the basic length and time. Spacetime is relational to all elementary particles of the entire universe. Therefore, there is no pervasive spacetime forming a background; and spacetime is, in the end, the actual trajectories of particles. Then there are electric charges which are intersections between two different dimensions of spacetime, but this is another story. I try to avoid mixing my theory to this section of the forum. There are many unresolved concepts in Physics while a majority of physicists think they are well explained and well understood.

[Bill S]

Sascha Vongehr has some interesting comments on energy here:

http://www.science20.com/alpha_meme/energy_not_golden_holy_cow_urine-72881

"Classically, space-time is static, and so E is conserved, which means if some is missing, we better find out where it went. However, energy in general relativity is not even expected to be conserved. If it is missing and we know well why it is missing, then why not? Why be traditional?

If E is not conserved, then a perpetual motion machine becomes possible. Exactly! Did you guys not yet realize that the universe is a perpetual motion machine of the worst kind? It not just creates E, it creates space-time out of nothing, violates the second law of thermodynamics, all of it. And I ask again, why should it not? Certain “laws” are applicable when certain symmetries are present for the system under investigation. These symmetries that describe the physics in our backyard may not hold for the universe as a whole, and why should they? They should not even be expected to hold".

[CPT ArkAngel]

If we are here to talk about this, it is because there is a basic asymmetry within the entire universe. This basic asymmetry could be motion and time itself. I don't think you can build a machine with a perpetual motion, because you would need to control the entire universe to do so. Being a part of it, it's kind of difficult ...

It doesn't mean energy is not conserved. Energy is always conserved locally and in any local experiment. The fact that it is not conserved in GR is due to comparing frames that are out of sync. By including non locality, you can keep energy constant by taking only synchronized frames. GR is fuzzy... no synchronization and lost in space... Though it is great, it is incomplete.

I think physics needs simplifications and more and better explanations, including of unknowns. The basic laws must be very simple. Finding simplified explanations explaining more is the key toward success.

[Bill S]

CPT ArkAngel, there are a couple of points in your last post I'd like to return to, but in the meantime; some thought I was having while waiting for a Consultant appointment.

Thinking about energy, I found myself wondering how many types of energy there might be: or could it be that there is only one?

Three types came immediately to mind: Mass Energy, Kinetic Energy and Potential Energy. 

Why?
Because they manifest clear differences.  They seem to relate to distinct situations, and each is relevant to its specific situation.

That said; I think it could be argued that there is only kinetic energy.

Why?
Because Einstein said: "The mass of a body is a measure of its energy-content".  This energy reflects atomic movement, so is, arguably, kinetic energy.

In the case of potential energy; the word “potential” implies that it is not actually energy, until it moves.  Thus, it is potential kinetic energy.

Could it, therefore, be argued that all energy is, at a fundamental level, kinetic energy?
 

[CPT ArkAngel]

First, it depends on how you define kinetic energy. Beyond Newton physics, kinetic energy has many labels and many forms.

I'm not entirely sure if I should say energy is "in the motion AND the curvature" or "in the motion AND/OR the curvature".

Time is not supposed to have a direction, it is a scalar. But what I think is Time has all directions in relations to the entire universe. For now, I see curvature and motion as equivalent in the same way inertial mass and gravitational mass are equivalent... It would be groundbreaking to find a single mechanism explaining all forms of stress energy and both gravitational and inertial masses!

But in the end, energy implies motion and motion implies curvature. An essential duality.

[Bill S]

But in the end, energy implies motion and motion implies curvature. An essential duality.

If energy implies motion, does that not imply that it is kinetic energy?

[Bill S]

I'm not entirely sure if I should say energy is "in the motion AND the curvature" or "in the motion AND/OR the curvature".

Wouldn't that depend on how the energy is held in the curvature?  That's something I've been wondering about since I first met the statement: "The energy is held in the curvature".

Time is not supposed to have a direction,

I thought time was supposed to have a single direction.

[jeffreyH]

The force of gravity has a special direction. Towards the centre of the source mass. That is the curvature of spacetime. It is a gradient in the gravitational potential. It is what allows a circular orbit to be stable.

[CPT ArkAngel]

There is still the possibility of half energy in motion and half in the curvature... Is there one coming first or they come in pair? Can you have more curvature while less motion and vice versa (or can they be out of phase)?

[jeffreyH]

There are various types of energy. Rest energy, equivalent to rest mass, kinetic energy, relativistic energy and potential energy. These are distinct. One type may affect another. Such as potential energy affecting kinetic energy. So it isn't just a case of portioning out energy so that some creates a curvature while another signifies motion. The study of tensors can be beneficial in understanding the mechanisms. This starts with a study of special relativity.

[yor_on]

BC the ability to do work is pretty nice, but what then about heat? The 'heat death of the universe' where the ability to do work no longer is possible. Would that then mean that this heat isn't a state containing energy?

I still like JP:s definition better. As a 'coin of exchange', although, thinking of it, the same might be asked there.

'Energy' is also something that people expect to be connected to 'time', as in the 'energy' of a vacuum being able to have no limit although then under such a short period of time that it becomes unmeasurable, if I now got that right :) I'll probably need to look it up, again ....

[CPT ArkAngel]

I was talking about a theory in which particles have real and unique trajectories.

If you move up your keyboard, you increase its potential energy. But at the same time you increase its timerate, by the same token you increase its internal speed... The external speed would have an equivalence in the graviton rate of update.

I proposed an internal speed V1 and and external speed V2 where V1^2+V2^2 always equal C^2. This is special relativity.

All type of masses are MC^2... Newtonian kinetic energy is 1/2*MV^2.

But this is just a theory! I needed to give more explanations, sorry!

I think curvature and motion are always in phase and they can`t be separated but I could be wrong. There are no explanation of internal mechanisms for energy nor time within elementary particles in the standard model.

In GR, Time has a direction from the past to present and to the future but it has no direction in space. Past, present and future coexist because there is no synchronization in GR.