Strange

But it is exactly the same result: more gravity on one side than the other. (You could do this on Earth by putting a large lump of lead (or, better, osmium) under one side). And it won't work for the same reasons. That is exactly why it won't work.

It needs maths. For example, your two "lemons": What is the significant difference between them? Their mass (or, perhaps, their weight). How do you know what they weigh? Maths. How do you know that they should land at the same time? Because that is what the maths says. What does "at the same time" mean? For example, I can guarantee that the concrete lemon landed fractionally before the real lemon. But does that invalidate the result? How much difference in time would be significant? Guess what: maths required. And so on... No maths, no science.

No, that is what we do. It is called "science". It requires a process based on evidence, mathematical models, testable predictions and willingness to admit an idea is wrong. All of which are severely lacking in the typical Speculations thread.

It appears to be equivalent to this: https://www.lhup.edu/~dsimanek/museum/unwork.htm#gravshld And won't work for the same reasons.

How do you arrange for the two fires or cups of water & microwaves to be identical without communication?

The only reason we would recognise this bit of randomness as meaningful is because someone else has already derived it from first principles and it has since been tested. Just making up random stuff and hoping it might be right is not science. I could write a very short program to do that. It certainly doesn't require any intelligence, artificial or otherwise.

How do you arrange for the two fires or cups of water & microwaves to be identical without communication? True. But what you mean by "logic" is "it makes sense to me". Logic is a branch of mathematics and you seem to be unwilling to use any form of mathematics.

How do you arrange for the two fires or cups of water & microwaves to be identical without communication? Why would I claim such a thing? I thought you were the one claiming that matter magically came from somewhere outside the universe. Anyway, I give up. You have no model that can be tested, things are just "obvious" or "logical", so you are clearly not interested in science. I think it is sad that you are not interested in using this as a learning opportunity. I'll leave you to your ignorance.

Apart from the fact that the CMB was produced long after the inflationary period, we can agree on that. Inflation ended after about 10-32 seconds. The microwave background emerged 380,000 years later. http://www.physicsoftheuniverse.com/topics_bigbang_timeline.html Try the explanation from an expert then: http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/universe.html And how do you do that without communication?

My point (in the previous post) is that in order to ensure identical conditions, you need communication; in other words some sort of causal connection. The chances of two fires being identical by chance are very remote. The chances that every point in space has identical conditions without some causal connection is basically zero.

Apparently not: I accept that there must be something that behaves like dark matter, because of the evidence. Currently, the evidence is pretty conclusive that "dark matter" is largely or completely some sort of matter. Explanations based entirely on modified gravity, for example, don't work.

I was listening to the radio on the way home and there was an interview with a scientist who studies fires. Interestingly, she said that no two fires are ever the same because there are so many variables.

What would cause that? It does. The so-called "mass increase" is relative. What causes the "mass increase" (apart from pop-sci articles) is known as "energy". And, as we have already seen, that is relative.

This is a complete straw man. No one ever said that there is no place for speculation in science; in fact examples of speculative ideas have been given. What is under discussion is the ideas presented in the Speculations section of this forum. These are almost always unscientific (not based on any scientific knowledge and refusing to accept any contrary evidence, for example). You said, or implied, that you think there is value in the made-up nonsense posted as "theories" there. Such people would make very poor scientists or engineers. They are both very creative disciplines. No. I would prefer them to understand that their idea is not science, to learn what science is, to learn some basic physics (or whatever) and refine (or abandon) their speculations based on that. What is a waste of everyone's time is those who insist that ,"my random idea must be correct because I thought of it and it is 'logical'".

"How it works" is a philosophical question: why is the universe like it is. I guess you could develop a set of theories based in a universe where inertia didn't exist. It would end up being very, very different from this one. Why don't we live in that universe? Ask a philosopher. And, again, what does this have to do with the fact that velocity is relative? Acceleration is not relative. Consider the earlier example of being in space with nothing visible except another space craft. If the relative speed between you and the other craft is changing then you can determine whether it is you or her (or both) that is accelerating. But you still can't determine anyhting other than your relative velocity.

How do you get to that conclusion? The sentence said nothing about angles, circles, circumferences or diameters... I don't know what it would mean for a "number to come to an end". Perhaps you mean, "the numerical expansion of which can never be written down." The exact value of Pi can, of course, be written down in a few symbols. But why that would be relevant to the question, I don't know. I believe the point being made was that the velocity and acceleration in this case are continuously changing. You can therefore, in the limit, view this as a continuous sequence of (infinitesimally small) instant changes. Basic schoolboy calculus.

Wrong. Science is a very specific and well-defined way of gathering information, creating models and testing them. Baking a cake is no more science than it is a piece of music. Almost no speculation on this forum is scientific. Very little of it even contains any science. A small number include a bit of misunderstood pop-science. Then it isn't science. Thanks for confirming that. Nothing is ever proven (in science). But that doesn't make it speculation; it makes it a system of well-tested, quantitative, productive and hence useful models. No they aren't. 1. "Theory of Everything" (which is rarely used by scientists) has a quite limited meaning and is certainly not intended to include "everything". 2. Even if it did explain "everything" that would no make "everything" science; it would just mean that "everything" was the subject of science. For example, water is not science, even though its chemical and physical properties are explained by science. I hope you see now why that is nonsensical. Then I cannot understand what you are doing on a science forum. If you prefer made-up nonsense to science, why not hang out on an art or SF forum.

PeterJ doesn't do specifics; he just makes vague claims about knowing more than everyone else.

Yes. Newton answered this for simple cases involving slow-moving objects: force causes [change in] movement. GR answers it for more complex cases such as gravity; this is how we understand why gravity is not a force, things in free fall are not accelerating and the universe is expanding. But I suspect that is not what you are asking. I don't know what you are asking. You would think the notion of inertia was completely obvious. But some ancient philosophers did think that there had to be a continuous application of force to make something continue in motion.

What "enables" it is the existence of space and time, I suppose. things can change their position in space over time. We label this phenomenon "movement" and quantify it as "speed". I fail to see what is so baffling about that. Yes. Why not? For some particles, that is the Higgs mechanism. Now you are back to philosophical, why is the universe like it is, questions. The result of a force, or moving along geodesics in space time. They seem like ill-formed questions that have no answer. http://www.youtube.com/watch?v=qjmtJpzoW0o

More on this here: http://www.newscientist.com/article/mg22429944.300-little-reactors-may-be-best-path-to-nuclear-fusion.html

I remember reading that in about the 12th century (I think) there was a change in the way people believed digestion worked. Previously they thought it was something similar to decay. As such, it was thought that porridge-like and soup-like foods would be healthier because they were similar to things that were rotting. Then it was decided that digestion was closer to burning and so there was a change to eating "burnt" foods: roasted, baked, fried, etc. I don't know how much truth there is in that. (Sorry it's off-topic, but after fiveworld's "contribution", surely anything is an improvement...) As for drinking, I assume humans evolved to drink water at close to ambient temperature. There is some evidence that frequently drinking very hot liquids can contribute to diseases of the oesophagus, including cancer. I wonder if that is because you tend to drink more water (and faster) because you have been exercising? p.s. I'm afraid I missed the Quote button and accidentally gave you a down-vote. Maybe someone could kindly undo it?

Nope. Its a compass (or pair of ~es). You can tell by the fact it has a pencil on one end. And the title of the image file.

Then I have no idea what you are asking. What do you mean by "mechanics"? Do you imagine that when you throw a ball there must be little cogs and gears that keep it moving? From Galilean relativity, basic dynamics and Newton's laws (v = ds/dt, s = ut + 1/2 at2, f=ma, etc) through to general relativity, the concept and mathematics of motion are very well understood. What is puzzling you? If you push and there is no wall, then the thing you push will move. And ... ?

Inertia. But that is just another way of saying the same thing in a different way. But even if there were some absolute motion, that wouldn't change Newton's three laws, so the question doesn't seem very relevant. You are asking "why is the universe the way it is?" That is not a scientific question, it is a philosophical or religious question. There is no answer.