Strange

Our conclusion was that it was pretty much impossible to come up with a definition! It was a university course.

When I did religious studies, that is almost exactly the opposite of the approach we took. Are you saying this is not the case (or have I misunderstood)?

As no one has ever seen either, how could the world appear different? Can we assume you made this up, or are you going to provide a reference?

In the case of the lizard, it is almost closer to swimming than walking: http://news.nationalgeographic.com/news/2004/11/1116_041116_jesus_lizard.html Other animals rely on surface tension: http://voices.nationalgeographic.com/2014/06/19/walk-water-animals-science-weird-environment-world/

John Baez provides a good overview of the equations and their meaning, which includes more examples like the above. So, even if you can't follow the maths (me!) you should be able to get something from it: http://math.ucr.edu/home/baez/einstein/

I am not. I am just pointing out that you claim it doesn't is a baseless opinion (presented as if it were a fact). Please provide some support for this claim.

A discussion of "reality" belongs in the philosophy forum. It doesn't really have anything to do with science. Who claims language is gibberish?

The entangled particles are described by a single wave function, as such you can think of them as being a single "thing". When you observe that thing it makes the spin definite (and also stops it being a single thing - they are no longer entangled). This entangled "thing" can be spread over half the universe, but that's OK because quantum effects are inherently non-local anyway (in time and space).

The thing is, they have a number of properties some of which we (classically) associate with waves (such as wavelength or frequency) and some that we traditionally associate with particles (such as being indivisible, momentum*, etc). They are neither waves nor particles. They might look more like one or the other depending on which properties you are measuring. *OK, not strictly true, but I was struggling for an example!

It isn't used in physics. It is, a far as I can tell, a pile of steaming wombat's poo.

In that case c=1.

Wavefunction collapse is just an interpretation (a metaphor, if you like) of what the mathematics says. There are many other interpretations (many worlds, transactional, etc) all of which are ways of describing or visualising what the mathematics says. They all describe the same theory and are thus indistinguishable by science. You can take your pick of whichever appeals to you. https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics They are always both wave-like and particle-like. The idea that they switch between being particles and waves is another bit of bad journalism.

I added "if you will" to indicate that some interpret that geometry as describing reality, while others just think of it as a model that works. I don't really have an opinion. I don't think so. It is an arbitrary preference as to where you want to draw the line between models and reality, with idealists at one end and naive realists at the other.

I think that is an example of sloppy journalism (quite possibly, the journalist doesn't understand either). I don't think you can.

They could be minute scratches/imperfections in the glass that act as nucleation points. Or it could be some residue that you can't get off. Glass bonds remarkably strongly to water-based materials.

Ah, I missed that you had qualified it like that. I was re-reading the original post about it.

I am slightly doubtful about this claim that half the electrons must be spin up for a couple of reasons. Firstly, as you say, it can only apply to electrons that are in a determinate state and secondly, even if their total angular momentum were conserved it isn't obvious that it must be zero.

I think that is what I was trying to say! I don't think the geometry is a metaphor; that is what the theory is (and what reality is, if you will). The metaphor comes in when this is visualised as a rubber sheet or some "thing" called space being curved.

Correct.

As far as I can tell, yes.

As we have no access to the signified ("reality") other than through our models, and don't even know if it exists, such discussions are outside of the domain of science. We observe things, make models, test the models and make better models. It is purely a matter of belief whether those models pertain to anything real or not. Apparently this question is of great interest to some people. (There is a thread devoted to this subject on another science forum which has been the most active thread for about 2 years but, as far as I can tell, the same people are still just saying the same things!)

I certainly can't follow the mathematics of GR, but I have learnt enough to know that "space curving" or "space expanding" are just images or metaphors to describe the maths. The important thing is to remember that and not start trying to extrapolate from those analogies (or as some people do, try to falsify the science based on those analogies). Geometry, even before GR, was just a way of describing (mathematically) the relationships between points in space. What GR added was the knowledge that these relationships are (a) not fixed and (b) not based on traditional straight-line Euclidean geometry. I don't think they are used significantly differently.Roughly, "space" is just the distance between objects and "time" is the separation between events (although "event" does have a slightly more specific meaning in GR). In other words, space is what rulers measure and time is what clocks measure. Of course, there are philosophical discussions to be had about the nature of time and space, why we perceive time as only going forwards, etc. But they are independent of the physics. (And, "space" can also be used to mean the stuff that is out there beyond the atmosphere: gas, dust, virtual particles, stars, planets, etc.)

I have no idea. But a rational approach is the only way to attempt an answer. Believing that "god(s) did it" is a non-answer and prevents further enquiry.

So you get the idea it is a metaphor. Good. But then you take it literally. Not so good.

Because there is no substance rippling, just the geometry of the distances between things. You don't think of length as being a substance, so why should changing length be a substance?