A few years with a half-life of less than four days? I doubt you could perceive any glow after more than a few weeks.
In a year the radon would've undergone about a hundred halvings, so around one 10^30th of the original radon nuclei would be left. Which is to say, almost certainly zero. One mole worth of radon would've decayed down to the last atom after less than 300 days (mostly to lead-210, which would then comparatively slowly decay to stable lead-206 with a half-life of about 22 years).
In John Adams' Harmonium, I was surprised to learn the basses go into treble clef for a second. I hadn't sung untransposed treble clef in many years! I think it was only an F#4 or A4 or something but it felt real strange to be singing in the treble clef again.
Living in Finland, there's always news about tens of thousands of households being left without power for days after particularly heavy winter storms. It works as a reminder that yes, some people do still live in rural backwoods, their local electricity distribution depending on fragile wires suspended on wooden poles. Whereas living in a town of any size, blackouts caused by weather simply never happen.
Since the Tapani storm of 2011 there's been a massive undergrounding of the power grid, so much of the rural areas are now also quite safe from outages. But there are still a lot of the old type of grid left and the economics for undergrounding those are increasingly unfavorable. Perhaps grid connected batteries next to the transformers might soon be more economical for many of these areas. They could serve other functions beside backup power, after all.
Yeah. That's partly why it feels so foreign to me that these blackouts would still affect tens of thousands of homes.
The Tapani storm was such a divisive experience. In the city the only effect of the storm I remember was that the windows were ringing quite a bit that night. Otherwise nothing out of the ordinary.
In most contexts days is perfectly normal, and expecting a faster reply, especially without explaining why it's urgent, is considered impolite. This includes all the cases where the job of the recipient is not literally "reply to e-mails ASAP".
I'm pretty sure that most people are only dimly aware of the existence of the quoted part at the bottom of an email. Mail clients routinely hide it by default, and in most cases it's never needed for anything in today's email conventions. Most clients now group conversations to threads, and most emails aren't long or complex enough to require much context anyway, never mind the custom of interleaving quotes and replies.
The vast majority people didn't yet use email back when bottom posting was good etiquette and top posting was discouraged. They're simply not aware of the concepts, or the controversy, at all. Even old-fashioned snail mail letters, for those who still remember such things, didn't usually include quoted passages, even though getting a reply to one's letter could easily take weeks if not months.
Because near/mid infrared has many uses other than high-z objects, and it’s been something of a relative blind spot to us until now, although before Webb we did have Spitzer.
For far IR/submillimeter observations we had Herschel in space, SOFIA in the stratosphere (flying on a 747), and several large terrestrial telescopes at very high altitudes can also observe at FIR/submm wavelengths. But sure, there are likely many astronomers who would love nothing more than a new spaceborne FIR telescope, given that it’s been more than a decade since Herschel’s end of mission, and SOFIA was also retired in 2022.
For microwave we’ve had several space telescopes (COBE, then WMAP, then Planck), mainly designed to map the cosmic microwave background. That’s the farthest and reddest that you can see in any EM band, 300,000 years after the big bang.
Past microwave, that’s the domain of radio astronomy, with entirely different technology needed. We have huge radio telescope arrays on the ground – the atmosphere is fairly transparent to radio so there’s no pressing reason to launch radio telescopes to space, and their size would make it completely infeasible anyway, at least until some novel low-mass, self-unfolding antenna technology.
This may be a silly question, but would you be able to create an interferometer style telescope array in space via a platform like starlink, ie small, inexpensive sats? Would that reduce/eliminate the need to launch large singular antennas?
That would probably be difficult at optical wavelengths. At radio wavelengths you might have a better shot, but we can build radio interferometric telescopes on Earth and since the atmosphere is relatively transparent at radio frequencies, you probably aren't going to get any advantage by trying to build one in Earth orbit.
...and your spatial resolution is proportional to the size of your telescope. So you could have really high resolution if you speckled your interferometric telescope array units around L1, L2, L4, and L5.
In a year the radon would've undergone about a hundred halvings, so around one 10^30th of the original radon nuclei would be left. Which is to say, almost certainly zero. One mole worth of radon would've decayed down to the last atom after less than 300 days (mostly to lead-210, which would then comparatively slowly decay to stable lead-206 with a half-life of about 22 years).
reply