J.C.MacSwell

Right. As I said in my earlier post, isn't it just assumed to be where needed? If say, you assumed it was where not needed it would not fit at all...so nothing really special about the fact that it matches... ...or am I missing something?

I don't think that is correct. I think the amount, and positioning, that is required varies in different Galaxies. If I'm wrong and the amount and position is consistent wrt ordinary matter in some way...why would a modified gravity function not fit just as well?

"2.) Modified gravity: When you look at rotating galaxies... ...When we add dark matter, they all match. When we modify gravity, the modifications we need to make to solve one problem fail to solve the others. " The problem here is that of course it would match...you get to assume it is exactly where needed without basing it on any observation but the observation you are hoping to resolve. Until that changes modified gravity needs to stay in the game, even if it is the lesser likelyhood.

That would be the intent

Starting out just the 1 kg, otherwise empty...I think that was the idea

Yes. When it's moving, when it's a photon, it travels at c.

If it's not at c, it's not a photon...

If you are wondering why it's there twice...just my incompetence...I tried several times to edit one away.

What? You don't like my perpetual motion machine design? (others might call it an Escher drawing)

"It" would be the universe. I really don't know why a universe would expand, contract, or stay the same but thought mass density might have something to do with it.

Would it not depend on it's initial size? If it is small enough it would stay small or even contract? If it was expanding what would drive the expansion? (or is that unknown but assumed since this one does?)

That's a reasonable assumption. Possibly the most reasonable? (I don't know)

They would presumably follow a geodesic until it showed up in front of them...or not...but that would depend on the metric.

This was my thought as well wrt the size and metric of this universe, and whether equilibrium could be reached (expanding, contracting, static somehow etc). No other matter to radiate back (initially at least), but maybe it all comes back, reradiates etc etc. If the universe is small enough our kg might stay nice and toasty.

It would depend on the size and metric of this universe would it not? I guess if it is a 1 kg "mass" that might put limits on what is possible... It could reach equilibrium, or not, at or from almost any temperature where the matter itself is stable If, say, it was isolated (read remote) in this Universe it would be at or heading toward 2.7 K

For "perpetual motion" I tend to think in the same context as yourself and Swansont when it regards machine design especially, or physics generally, but the term is also used in the context Studiot describes. Wiki, for example, seems to look at it as Studiot does: https://en.wikipedia.org/wiki/Perpetual_motion Just my (overpriced no doubt), $0.02

+1 for the first honest perpetual motion claimer ever!

How about the idea that the present Laws of Physics don't allow it?

From what I've seen of many a successful perpetual motion machine, a little misunderstanding always helps. Cycling of seemingly insignificant errors until they add up to something special seems to be the key, and if all else fails when making a prototype, just cheat a little, put it on You Tube and by all means ask for money...you are after all saving the World at the expense of greedy oil and power companies...

If you want to get a bit of the flavour of string theory without the math Brian Greene's Ted Talk on the subject is interesting: https://www.ted.com/talks/brian_greene_on_string_theory#t-4218

Yeah. No magic involved. There has to be sufficient water in the air, and the collecting surface needs to be maintained below the dew point. Tough to do that in very dry conditions.

Looks like it was quite effective: Note that it was pretty much as Studiot described and used the Sun to heat the very damp soil. It did not rely on night time cooling.

It doesn't with the plastic, no. But it generally does for the most part where the cooled surface is exposed to the air. I was picturing a dehumidifier when I initially wrote that before remarking on MigL's suggestion.

What I meant by surrounding air was the air immediately surrounding the cool surface...so probably a bad choice of wording. And as you suggest raising the humidity of that air can also help, especially in dry air conditions. What MigL described is typically done overnight, taking advantage of the warmth remaining in the soil and the cooler exposed plastic. You are describing something closer to a solar still. It can be quite productive if there is a lot of moisture in the soil, even with the plastic likely to be above the ambient temperature. In this case it is best if the plastic is sealed around the perimeter. At some point we are crossing a line of getting the water from "thin air" if that is the goal.