You talk about ""science" --- the one with hypothesis, testing, reproduction of results". These things do kind of apply to cosmology. Hypothese are about things like the statistical distribution of galaxy sizes and redshifts, or the exact spectrum of the cosmic microwave background or the proportions of elements in the oldest stars or ... The speculators are working out these prediction so that the observational astronomers can test them with their next set of instruments. Or in some of the other areas, about what we will see in the LHC when we reproduce on a very small scale certain conditions.

Reproduction of results is harder, because we only have one universe, but people only become convinced of an explanation when there are multiple chains of evidence supporting it. So dark matter is supported by galaxy rotation, features of the cosmic microwave background spectra, gravitational lensing AND siumulations of galaxy distribution.

Actually it lasts only about a millisecond, but the 1 MYears of solar output part is right. It's about the mass of the moon converted to RF energy in
1 ms.

Constant approaching velocity is special relativity again, and again the velocities don't add the way you expect.If the planets in your example are approaching at 2/3 c they each see the other approaching at 12/13 c and they will very definitely and messily interact. Each exists for the other.

In this case acceleration makes no essential difference though. In either planets frame of reference there is an event horizon behind it (in GR acceleration and gravity are equivalent) but none in front of it, so they can see each other and interact freely.

If you're dealing with constant velocities, you are in the territory of special relativity. In this world there are no event horizons and every object can interact with every other. If two galaxies are each receding in opposite directions from a third central one at 2/3 c they will each see the other receding at 12/13 c according to https://en.wikipedia.org/wiki/... (section 2). Velocities do not add up the way you think they do and when they get to a decent proportion of light speed it starts to matter. This has been experimentally checked using moving atomic clocks. Thus they can keep on exchanging messages, although the messages will be quite redshifted when they arrive and take longer and longer to make the journey.

However, the original article deals with accelerating motions, since that is what the universe seems to be doing. This is crucial.

One way of seeing what happens is to imagine two galaxies accelerating away from one another. Assume there are clocks freely falling in both galaxies.
Define a function f so that a signal sent from one galaxy at lightspeed (could be photons, gravitons, neutrinos, doesn't matter) at time t on the local clock arrives at the other galaxy at time f(t) on its local clock. It's not hard (for anyone with a degree in astrophysics) to work out exactly what function f is. It turns out that there is critical time T such that as t approaches t from below, f(t) approaches positive infinity. In other words the last few signals emitted by one galaxy as it's clock ticks towards T are spread out across the whole of the rest of time when they finally catch the other galaxy and no signal emitted at or after time T can ever arrive. The critical time T depends on the current separation, velocity and acceleration of the galaxies in a fairly straightforward way. After local time T nothing you do can affect the other galaxy. After its time T you can never find out what happened to it.

Could do, although there is no evidence of such an effect up to now. The laws of physics could also just change tomorrow for no particular reason, in thi sarea, or in some much more down-to-earth one, like whether the proton is stable. We can never know.

The article is essentially in the business of explaining the consequences of the laws as we currently conjecture them to be (which fit what we can observe pretty well). It can't make any stronger claim to be "correct" than that, but, apart from refining "pretty well" to "very well" nor can any physical theory.

Of course. Anything could happen, but there is a remarkably consistent, and mathematically simple, if somewhat unintuitive picture emerging of how the universe has evolved on the largest scales. The picture in general (dark matter, dark energy, etc,) is consistent with a number of independent sets of data, for example supernova surveys and detailed analysis of the cosmic microwave background. The article is trying to explain the consequences of this picture.

What we can see are galaxies at very high redshifts and evidence for accelerating expansion. If the dark energy explanation for the expansion is right, then lighjt emitted from those galaxies (which we can see) a few billion years after the light we see them by now, will never reach us. Of course some unknown thing could intervene to prevent this happening, but we see no sign of such a thing yet.

What sort of proof do you want, and how does gravity come into it? Happy to try.

You're right, but you've misunderstood my point. If A, B and C are all "far" apart then all the distances are increasing at an accelerating velocity and the situation is as I described it. The last paragraph deals with the special case where B and C are close enough that they are not accelerating apart. In this case B and C will remain in contact forever, and so A will lose touch with both of them at the same time.

Doesn't work. If you try and relay light (or any other message) along the line from the distant galaxy to us, what happens is that it reaches each relay station just as the relay station loses contact with us. It never arrives.

Both true, but these interactions don't combine. Suppose you have three galaxies in a line A--- B---C and A and C are just leaving causal contact.
Suppose a light-speed message is sent from A towards B and C. B will indeed receive it, and be able to reply to it (maybe) but that will happen just as B and C leave causal contact (the universe having carried on expanding), so that if that message is forwarded towards C it will still not arrive. The photons in the forwarded message cannot overtake those in the original message that are still flying from B towards C.

If B and C are close enough to be gravitationally bound then A will lose contact with both of them at the same time.

Real-time audio translation is just taking off. By 2115 everyone should be able to speak and hear others speak in whatever language they like, including perhaps one that they and their personal AI made up as they were growing up.

If you go back to the original papers you will (by and large) find all the disclosure you want. The problem is that that mans reading and understanding tens of thousands of pages of complex mathematical arguments to see how each aspect of the data analysis was arrived, at, validated, etc. You are (probably) reading summaries of summaries of summaries of review articles of the papers. Complete disclosure there would make the documents thousands of times longer and completely unreadable.

On current trends solar and wind are set to hit that goal within a decade or so. There are some interest engineering problems around storage/demand management and power transmission, but the trend lines look quite good. Especially if you enforce even reasonable local environmental standards on mining and burning coal.

Just about all European players have or do reprocess -- France at Cap de la Hague, the UK at Sellafield. It turns out to be
remarkably messy, difficult and expensive, and very prone to radiation leaks of one kind or another. It was only really economic when there was a military market for the plutonium at basically "any price".

The problems are not fundamental, they are all engineering, but there were lots of them, and they never really stopped. You're working with something that has a horribly mixed chemical composition, and was designed (as a fuel element) to be tough enough to survive inside a reactor for a few years. You have to dissove everything in loads of hot concentrated nitric acid just to get started, so now you've got industriial quantities of hot radioactive acid laced with a not exactly known mixture of salts, plus insoluble sludge of one kind or another gunging everything up. And you can't ever go into the plant to unjam a conveyer, clear a stuck valve or clean a filter.

A modern wind turbine in typical European conditions generates enough energy to "repay" the costs of building and installing it in about six months. http://www.theguardian.com/env...

Backup can mostly be other renewable sources (solar, hydro, biomass) demand management and storage (pumped water at the moment). For the rare but real occasions when none of this covers the need, cheap gas turbines designed for a low duty cycles seem like the best option.