Strange

I guess one advantage is that it increases greater opportiunities for diversity. Plants that spread by spores can only be cross-pollinated by the wind. Plants that use bees or other animals, can cross-pollinate over a much wider area. Also, the pollination is more targeted (efficient). Instead of just releasing some pollen into the air and hoping tjhat some reaches another suitable plant, it is carried from one flower to another. I'm sure that there are many more advantages (and some disadvantages).

Science is the process of building models to describe the world around us, based on the evidence, and then testing those models against further evidence.

Yes. what would you like it to tell you? It seems to be a remarkably successful theory.

So, life creates greater diversity of environments which drives greater diversity of life. What was your point again?

You can ignore all the evidence for expansion and misinterpret things that way if you want. It's a bit sad, but it's your choice. That is evidence for the model. The model that tells us that the universe is denser in the past. Apparently not.

If the 2 galaxies are sufficiently far apart, that metric expansion is relevant, then no. But if my head and feet were that far apart then they would not be affected by expansion because they are held together by inter-atomic forces, so yes. Asking physically impossible questions rarely leads to sensible answers.

http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence The trouble is, you are treating what we see as the way the universe was then. But that doesn't take expansion into account. Those widely separated galaxies were much closer together (i.e. the universe was denser) when the light left them. The further back/away we look the more expansion has taken place and so the more "correction" must be done to calculate what the actual density was then; in other words, the further back we look, the more dense it was but the less dense it appears now. This answer is kind-of related: http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN

I still don't understand why you think your head and feet are at different times. Mine aren't.

Indeed. That total force is distributed evenly over the entire surface of the water. And there is an equal and opposite force in the opposite direction (at every point). So if we want to work out how much force is acting to hold up the water in the tube, we can take that total force and divide it by the fraction represented by surface area of the tube (as a proportion of total area). This gives us the total force pushing up on the column of water. Now we need to know the total force pushing down due to the column of water (these two obviously have to be equal). This force downwards is given by: density x height x g x area. And there is your equation containing area! Note that if you increase the area of the tube, you will increase the force pushing up and the force pushing down by the same amount. So the height is still the same.

Your figure seems to be about two orders of magnitude larger than other estimates: http://en.wikipedia.org/wiki/Observable_universe#Mass_of_ordinary_matter (I haven't gone through the "Extrapolation from number of stars" to work out where the difference might come from. Overestimating average star mass, would only seem to account for a factor of 2.)

Ideas like this have been (and are being) looked at before. http://www.physlink.com/Education/AskExperts/ae191.cfm http://en.wikipedia.org/wiki/Geon_%28physics%29 http://en.wikipedia.org/wiki/Black_hole_electron http://www.technologyreview.com/view/413483/could-all-particles-be-mini-black-holes/

I'm really not sure what you mean by all those straight lines. But, in general, I would say no. In the presence of gravity (i.e. pretty much everywhere) the photon will follow a path that is not straight. (But then we get into what the word "straight" means. Arguably it is the path a photon follows. That is why this sort of verbal question doesn't really have an answer; it is too ill-defined.)

No. FORGET the circles. It is a 1D representation therefore circles cannot exist. They were just a little joke based on your comment about heads and feet. They don't exist and are not relevant to the diagram. The only relevant part of a diagram is a gray quadrilateral. This shows your extent in space and in time. As you cannot time travel (I assume) your head is not at two points in time; it has extent in time for the period of its existence.

I don't know if this can be explained except with the mathematical model. You are not seeing a snapshot of the universe as it was in the past. You are seeing it with the effects of expansion. In other words, those galaxies were closer together when the light was emitted (for example, the furthest galaxies we see were only about 4 billion light years away). But they appear further apart now because space has been expanding during the time it took light to get here.

You are taking my crude, 30 second sketch too literally. There is one circle (your head) which exists across time (in the same way it exists across space).

One. Really? Do you see an infinity of yous in the spatial dimension as well? It is intended to show that you have extent in the temporal dimension in the same way you have extent in the spatial dimensions. Not "a" you at all times, but simply you at all times. *shrug*

I don't understand the question. "How"? The usual way: variability, heritabilty and selection. But there is a complete range of transitional forms between plants that form spores on leaves, those that have specialised seed forming parts, those that then surround those with distinctive leaves (colours and smells), those that go on to form recognisable flowers (and everything in between). The advantage is, presumably, to attract animals that will pollinate and/or disperse the seeds. I don't know about "benefits" (does that make sense when talking about evolution?) but there will be various species that co-evolve to pollinate and feed on particular plants. Then predators (including plants) that feed on those. And organisms that imitate the predators and ...

Even massless photons are affected by gravity. This is easy to show, even with Newtonian gravity (and easier to explain in GR). I am not aware of any evidence that photons have mass. But they do have momentum. The only differences are due to their different wavelengths. Mass is not a factor. They are both wavelike (as is everything) and so they are both diffracted and both show interference patterns.

You can, of course, choose that. But there is no reason to consider it special, or even unique. It is just your (arbitrary) choice. There are other large masses, such as the Shapley supercluster, that contribute to our motion against the CMB. You could equally well choose one of those. Or the center of a large void. Or a particular star. Or ... An "absolute" reference would require physics to be different when considered with respect to that reference. (WHich is why there is no such thing.) Indeed. The universe appears be like that (or, at least, our models of it are - which might just say more about us than the universe). And that is exactly why there is no absolute reference. It would make physics "lop-sided". The laws of physics would change depending on your position and speed. We don't expect that to happen, and there is no evidence that it does. Or they are all equally arbitrary. Either way: none are absolute.

Actually, we can see galaxies that are receding faster than c.

I'm not sure that definition works very well, Mike. Not for all properties of "things" anyway. For example, velocity, momentum, length and energy (among other things) are all observer dependent properties even for "real" objects.

Good article here about the importance (and difficulties) of adjusting your language for your audience: http://stroppyeditor.wordpress.com/2014/11/27/physician-explain-thyself-science-english-vs-lay-english/

I am not talking about equations. I am simply pointing out that changing distance (and the corresponding changes in travel time) do not require an aether. But actually your equation is wrong. It fails to take into account the fact the distance is changing while the ball or light is travelling.

It is a definition. I am not saying it is true, I am just pointing out that without defining the terms, the discussion is meaningless. And the answer depends on the definition. How do you define "real physical object"? But, sticking with my definition: "real physical objects are made of atoms". By this definition, electrons, baryons and, yes, photons, are not real physical objects (because they are not made of atoms). The sneaky question I was expecting (because I hadn't worked out the answer) was: are atoms real physical objects according to this definition? But, as you point out, we are mainly made of nucleons, which weren't made this way.

Thanks for your polite conclusion to the discussion. Well, yes. We knew that! The problem was not with the idea (it seems likely that a successful theory of quantum gravity will require space-time to be quantised; or at least, for continuous space-time to be emergent from some underlying quantised structure).