Ziggurat said:
It's not a strawman if you actually said it.
It is a strawman if you take *one sentence* "out of context" and ignore the conversation that led to that sentence. The debate was whether or not we live in a "net zero" energy state universe. In the pendulum example it was clear we could indeed set an *arbitrary* reference point and use negative signs in our mathematical models of the movement of the pendulum. That has nothing to do with "zeroing" out the whole energy of this physical moving, expanding, accelerating, universe.
You might have a leg to stand on as it relates to a "net zero' energy state, *if* Guth did not begin with a "thingy" that possesses "heat'. Since that is certainly the case, his theory is not a "free lunch" theory, it is a "net positive" energy pre-mass "thingy" that is evidently *full* of "heat". How is "heat" not 'net positive energy"?
sol i got the ball rolling, with
post #832 (extract): "
All solutions to general relativity conserve energy - whatever energy goes into matter and radiation is compensated for by an increasingly negative gravitational potential (just like a rock falling)."
To which MM replied, in
post #835: "
Whaaaaaaaaat? Are you trying to tell me that the universe has a net zero energy now?"
In #836, Zig said: "
Of course. Didn't you know? Of course not: you're clueless about GR even though you think you aren't. That's bog-standard GR, too: it applies regardless of the mechanism which stores energy, so it's a feature which is independent of dark matter, dark energy, and inflation."
Now most people, when in a hole, would stop digging ... or at least go check out GR, as Einstein taught it (should I make that a quote?), to see if si and Zig are, in fact, correct (remember, this is a straight-forward question, about GR).
Sadly, MM chose to continue digging.
In
#846, si gives the textbook (GR) answer: "
GR 101. That follows immediately from time reparametrization invariance. Of course one can find definitions of the energy that aren't zero, but they amount to writing 0 = E - E (with that split done in a particular way)."
If I were MM, I'd be crimson red with embarrassment by now, having so clearly and so spectacularly demonstrated ignorance of the very thing he said he took as central to "EU theory" (i.e. "GR as taught by Einstein"), but then comes the cross-over to classical physics (no sign of any pendulum, or PS).
In
post #857, Zig explains what "negative energy" is,
in general: "
In electromagnetism, fields store energy with a density proportional to the square of the field. If you bring two like charges together, this means that the energy stored in their electrostatic fields increased. That's why it takes energy to push them together: you do work to create positive potential energy. But gravity is different: when you bring two like gravitational charges (ie, masses) together, you get work out of it. So the energy stored in the fields is negative: the volume integral of the field squared increases as you extract work from gravity."
and makes the connection with GR: "
Energy is a mathematically well-defined function. The way this function is defined in general relativity is not arbitrary, and while it may not be a unique definition, it is rigorous."
In #858, si also gives a simple -
general - explanation: "
Two rocks in an empty universe, at rest, far apart. Call the energy zero (or call it 2Mc^2 if you prefer). Let them go; gravity pulls them together. They accelerate, gaining kinetic energy. But total energy is conserved - so therefore their gravitational potential energy becomes more and more negative as they fall together.
Gravitational potential energy is always negative. That's primary school physics."
(still no sign of pendulums or PS)
And what does MM do? Why, accelerate his digging! (#866): "
With your Gumby brand of GR, you're telling me they accelerate *away* from each other and the whole thing has a zero energy state! Talk about bizarre religions."
A few more rounds of MM displaying spectacular ignorance, not reading (or perhaps just not understanding) very simple posts that set him straight, ...
Then in
post #882, temporalillusion brings the discussion back to classical physics again: "
I remember talking about gravity being negative energy a looong time ago in school, and not even in the context of GR!
Correct me if I'm wrong but isn't the equation U = -GMm/r?
Put the radius to infinity (for zero gravity when things are infinitely far away). Anything closer is negative."
Then more acutely embarrassing stuff from MM, posts by Zig and si that clarify what the physics is, the difference between classical and GR, etc.
si's
#886 contains a gem, because of how MM responds to it (in
#891) ... this is just too good to pass up*:
sol: "There is nothing mysterious about negative energy in any pre-GR context - and in fact in any classical theory with point masses or point charges it is impossible to make all energies positive (because the gravitational or EM binding energy can be arbitrarily negative)."
MM: "
BS. This is how I know that you're making this all up. You can in fact add and subtract and play with constants and do anything you want with the math. In the real world however *physics* matters and that is how I know your are whistling dixie on this topic. The universe is *FILLED WITH* energy. It has always had a positive energy density. In the world of actual "physics", physical particles contain and convey energy, real *positive* energy. You can't tell math from empirical physics."
Several more rounds follow, with Zig trying mightily to explain the classical physics concept to MM, and MM continuing to fail.
Then comes PS' post #920: "
I am not familiar enough with the physics involved to comment on the concept of negative energy from the perspective of cosmology. However, in general, the concept of any quantity in nature being negative is one of convention from the perspective of the mathematics used. It all depends on where one puts zero. Negative points on the real line are just as valid as positive points. Similarly, any quantity that can be increased or decreased can have a negative value at some point, which will depend on where one assigns zero. It's that simple.
I can place an object on a table and decide to assign its gravitational potential energy at zero. If I raise it a few feet I can now decide it has a positive energy . If I lower it under the table it will now have a negative energy (in my coordinate system). I have no doubt that valid results can be obtained in doing physics using this convention. The fact that the energy is negative under the table has no mystical meaning; it's merely a way of doing the math."
More attempts at education follow, MM continues to fail (and continues to be very belligerent about it).
Finally, in
post #937, Zig introduces the math that leads later to his killer question: "
Clue for the clueless: there are plenty of physical systems with no lower limit to the potential energy. In fact, anything with an attractive 1/r2 force will produce a U = -1/r potential. You can try to make that potential positive by adding some constant (ie, U = C - 1/r), but since there's no lower limit to -1/r, the potential can always go negative no matter how big a constant you try to add. So you're completely wrong, and the proof was trivial."
PS, who's obviously been reading along, patiently, can stand it no more (#940, bold in original): "
You have a fundamental problem! You make no attempt to learn from or even pay attention to any comments made here. Simply put, you are in combat and don't really make an effort to learn from or understand someone else's remarks. Your response above is nothing more than a quick knee jerk answer with no thought.
That's not science; it's dogma! You are not engaging in a scientific discussion; you are spouting blind MM dogma.
If you were to make any attempt to understand my comment above, you would realize that any system can be described as having zero energy. Then as the system evolves (in isolation) various aspects or parts of the system can have positive, zero or negative energy with the total system energy remaining at zero, which would be consistent with the conservation of energy law you know so well. That is true of the whole universe, which is a system (a big one)."
And so it goes, for at least another page or two.
It'd be really very funny ... if it weren't so sad.
Oh, and MM: all the posts are there, for anyone to read; suffice it to say that this last post of yours that I'm quoting is quite wrong (as I have just shown).
*
oh, and in #890 MM introduces the pendulum ... no sign of PS ... MM quotes Zig, and the context is classical physics