Exciting Black Hole news!

Most "Two Black Holes to merge" stories go like this, from Space.com:

The two black holes dance around each other at the center of the galaxy NGC 7727, located some 89 million light-years away from Earth in the constellation Aquarius. Scientists say they have never seen such a pair so close to our planet, but also so close to each other.

The black hole couple, which will merge into one giant black hole 250 million years from now...

That's not exactly a testable prediction, is it?

Imagine my surprise when I stumbled across this article on Inverse:

ASTRONOMERS ARE WATCHING THE SKIES, waiting for two cosmic giants to collide. In a galaxy located 1.2 billion light years from Earth, a pair of black holes could potentially be engaged in a gravitational tango, pulling closer to one another until they merge as one supermassive black hole.

This could occur as soon as 100 days, or up to three years from now*.

The chaps at LIGO/Virgo have got a lot riding on this. So far they have been marking their own homework, although their output has the ring of truth to me. Equally, they could be pulling a massive scam like all the scientists wasting billions on Dark Matter detectors.

So, let's hope that Huang Nang and Ning Jiyang (who arrived at their conclusion independently of LIGO/Virgo "using data from a survey telescope in California called the Zwicky Transient Facility) are in the right ball park and that the merger can be detected by LIGO/Virgo. That's both parties vindicated and we'll learn something new, or have some existing theory corroborated. Or possibly red faces all round, but we've still learned something.

* Of course, either this event happened - or didn't happen - 1.2 billion years ago, but from our point of view, it hasn't happened yet.

Strange claim to fame.

Eris is the "second-largest known dwarf planet in the Solar System".

Let's see if Harry Dale Huffman's approach works with Titan

Titan is my new favourite moon/planet. It orbits Saturn, is a bit bigger than our Moon, and has an atmosphere that is strikingly similar to Earth's - it's mainly N2, with 5.65% CH4 to spice things up -  with a surface pressure 1.48 times as much as Earth's surface pressure.

Harry Dale Huffman pointed out that comparing the surface temperatures of Venus with the surface temperature of Earth 288K is a diagonal comparison. Venus' surface temperature is ~737K, largely because atmospheric pressure is 92.1 times as much as on Earth. A direct comparison is the temperature of Venus' atmosphere at the altitude where atmospheric pressure happens to be equal to Earth's surface pressure versus Earth's surface temperature, so we compare 338K with 288K.

Then you just adjust Venus' temperature down to compensate for the fact it is nearer the Sun and the solar radiation it gets is more intense. The adjustment factor is the fourth root of (2,601 W/m2 ÷ 1,361 W/m2) = 1.91 ^ 0.25 = 1.176*. Divide 338K by 1.176 = 287.4K, that's as close to 288K as makes no difference, job's a good 'un.

HDH does not claim to be able to explain why this is so (see discussion here), but that's just how science works. First step is observe stuff, recognise clear patterns, and then you try and work out why. His guess appears to be that you can ignore a planet's albedo when looking at temperatures, because higher temperature causes clouds; clouds increase the albedo; thus reducing incoming solar radiation; which would reduce the temperature. So we would end up in a circular calculation. Or something like that.
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OK, let's strap on our space suits, fire up the rockets and head off to Titan. Temperature at the surface is measured/estimated to be 93.7K. It receives 14.8 W/m2 solar radiation (same as Saturn, but knock off 0.8% because it is in Saturn's shadow 0.8% of the time and add on 0.08 W/m2 which Titan receives from Saturn itself).

Let's adjust Earth's surface temp (288K) down using the same method as above: 288K x ((1,361 W/m2 ÷ 14.8 W/m2)^0.25) = 93K. That's pretty close to 93.7K!

However... HDH's direct comparison method is the temperature on Titan at the altitude where pressure = Earth's surface pressure versus Earth's surface temperature, which happens to be at ~8 km. With a lapse rate of ~0.5 K/km, the temperature there is ~89.7K, against our predicted 93K. So it's ~3 degrees cooler than predicted by HDH's approach, which is still close enough, I think.

Which all demonstrates that a planet's albedo and the precise composition of its atmosphere are probably irrelevant, and whether or not the constituent gases can 'trap' radiation is almost certainly less than irrelevant.
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* The short cut is divide distances from the Sun and take the square root = (149.6m km ÷ 108.2m km) ^ 0.25 = 1.176.

Dark Matter and Dark Energy

Another nail in the coffin of Dark Matter and in favour of MOND and similar explanations here.
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Dark Energy is a different topic, and is a placeholder name for whatever causes galaxies to all be moving away from each other, unless they are fairly close and gravitational attraction over-rides it (by several orders of magnitude).

The clever scientists don't really know why this is happening, and there are different ways of calculating the rate of expansion which give different results (although they all seem to be within +/- 10% of each other).

I have spent a couple of weeks reading and trying to understand the page on Ozone Depletion Theory titled What is Electromagnetic Radiation?. I still only vaguely understand most of it, but this sentence grabbed my attention:

Light illuminates matter, but light itself is not visible, it is dark, until it interacts with matter. Given that Earth receives less than 5 x 10-8 % of Sun’s radiation, there must be a lot of dark energy in space that changes in time...

Woo hoo! That might be it. As a matter of fact, there is such a thing as solar sails, as popularised by Arthur C Clark, which use 'photon pressure' to gently but firmly accelerate a spacecraft. The rate of acceleration is painfully slow, but it is constant and cumulative, so they can get up to fair old speeds after a few years or a few decades.

So the logic is this: only a teeny-tiny amount of light emitted by a star hits solid matter in its own solar system or even its host galaxy; most of the light goes out into intergalactic space. A teeny-tiny amount of starlight leaving each galaxy hits solid matter in its own galaxy cluster, and so on and so forth. And in turn, each galaxy is being hit by light from all other galaxies; so they all act as giant solar sails.

As star light is nearly as old as the universe, those billions and billions of years worth of starlight from each galaxy (or galaxy cluster) is pushing each other galaxy (or galaxy cluster) gently but firmly away from itself and the cumulative effect is (just about) measurable (if you call ≈70 km/second per megaparsec distance measurable). By definition the rate of expansion must also be gently but firmly increasing.

Whether or not the universe has a "centre" (and I am prepared to accept that it doesn't, and it is not expanding into anything larger), this leads to its gradual expansion!
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This might be complete nonsense, but it's an entertaining thought at least. And seeing as its the only explanation I've ever seen, I'm going to stick with it for now until a better one comes along.

Thoughts on This...

From Toby Young in the Telegraph

When I have thought about it, I’ve thought that the best possible place to put any spare cash is into my home, because that’s likely to appreciate in value more than any other investment vehicle.

Do you think property’s a good investment then?
That’s indisputable, isn’t it? It’s not worth saying property’s a good investment. It’s a bit like saying: the sky is blue.
First, property’s unlikely to be beaten by any other investment vehicle, and second, you live in your home so it’s in your interest for your home to be as spacious and comfortable as possible. You don’t get any benefit from most other investment vehicles.

Does this really add up? OK, you get some utility value for your home, but you're paying a lot more in interest than the amount it rises. And you've got to heat it and maintain it. And you could put the money into other investments.

But there's also a thing I ponder about space in all of this. Me and Mrs The Stigler live in a house that's pretty snug. I'd prefer a little more space, she's not bothered, and I'm not that bothered, so we're not extending. On the plus side, that means we're living mortgage free.

We get around the lack of space by, if you like, outsourcing space. So, if my parents come to stay (which isn't often), we put them up at the hotel down the road. It's about £75/night, but a couple of times a year, that's going to be cheaper than financing the build of an extension to have a spare room that's sat empty. I like the idea of having an office at home, but in reality, I prefer to work where there's some background noise, like in a cafe.