speakeron

The temperature of the cosmic microwave background can be used as a universal clock.

It's actually Act 2, Scene 1 and is spoken by Polonius.

Oblate spheroids are round.

> Heathrow is massive and uses a lot of power (1-2MWh/day)

It's 3 orders of magnitude more: 1-2GWh/day.

https://www.heathrow.com/content/dam/heathrow/web/common/doc...

Just one ^n. Supermassive black holes are expected to have completely evaporated by 10^100 years.

It's not really whether it makes scientific sense or not, it's just that it's so very highly improbable (really, really improbable) that other explanations make more sense: the video's a fake, it's mass hysteria, or even that we're living in a simulation.

The use of a space as a thousands separator has been around since the 1940s as recommended by the International Bureau of Weights and Measures and it was what we used when I was a kid at school in the UK. They specified it should be a thin (half) space.

https://www.bipm.org/documents/20126/28433818/working-docume...

How can you tell from analysis of the physical circuit what assumptions the designer made about the flow of current? Surely the components (electrolytic capacitors, diodes, transistors, etc) are the same and can only work in one direction. Is it that the ground plane is connected to the positive terminal of the power supply?

I think the problem with gas stoves is the nitrogen dioxide they produce. Do you have a meter for that?

They have different magnetic susceptibilities. Gold is diamagnetic (repelled by magnetism); tungsten is paramagnetic (attracted). A strong magnetic field (neodymium magnets) and sensitive scales can tell them apart. I built a small rig a few years ago with parts from Aliexpress that worked for coins and for bars it's just scaling it up.

It's like the old joke about Vegans. "How do you know if a physicist is an MWI proponent? Don't worry, they'll tell you soon enough..."

You should take D3 with vitamin K2 (talk with your doctor first if you're on blood-thinning medications) to avoid calcium being dumped into soft tissues (K2 ensures it preferentially goes into bones).

It's a good idea to get your vitamin D status tested yearly and aim to be at least 50 ng/ml (120 nmol/l), but not more than 80 ng/ml (200 nmol/l).

As an example for dosages: I take about 7000 IU of vitamin D3 and 180 mcg of vitamin K2 daily. My levels test at about 180 nmol/l and my blood calcium is normal.

For the same field of view, a smaller sensor requires a decrease in the focal length; this leads to a greater depth of field. Moving to a medium-format camera will give less depth of field (and a large-format camera even less). Different sensor sizes using the same focal length will give the same depth of field, but the field of view will vary.

This explains it nicely: https://fstoppers.com/education/understanding-how-sensor-siz...

> Not sure the source but there is a rule in fiction that everything has a purpose, as opposed to reality. If the camera stops in an axe, you can be sure someone is going to wield it later.

That's from Anton Checkov.

https://en.wikipedia.org/wiki/Chekhov%27s_gun

This is from the University of Zurich (UZH), not the ETHZ. They're different institutions (UZH is a cantonal university, ETHZ is a federal one).

On my screen, it's taking about 4s to scroll one light minute (15 times light speed). So if the map extended all the way to Proxima Centauri, it would take over 3 months of continuous scrolling to get there.

Quark is from Finnegans Wake, not Ulysses.

A programmer walks into a bar, or not.

RAID 10 is more efficient (if that equates to performant) than RAID 6, but not more durable. In fact it's less.

As an example, a 4-disk array (which has the same capacity in both RAID 6 and RAID 10) has 4 2-disk failure modes. RAID 6 can handle all of these failure modes without losing data, whereas RAID 10 can only handle 2 of them.

It was this one from the Reina Sofia University Hospital in Spain (high dose of Calcifediol significantly reduced need for ICU treatment):

https://www.sciencedirect.com/science/article/pii/S096007602...

The problem with hardware RAID is that if the hardware fails, you need to replace that specific card with the same type to recover the data. If they're cheap enough and you want to go down that route, then buy two so you've got a backup.

On the server side, the tendency is now towards vertical striping (directly addressing disks on multiple servers through the network with software).

This thing is the size of Jamaica with a draft of 200m (and so a height of more than that). It would take multiple nuclear weapons to do it any real kind of damage.

My way of thinking of it is like this: imagine your eyes were located above and below your belly button (on a vertical axis). What would be 'flipped' when you look in the mirror?

The assumption of SETI has been that an advanced civilization is broadcasting a narrow-band (in the 'water hole' and possibly modulated) omni-directional signal using a large amount of energy. We can see stars across the galaxy (and, indeed, in other galaxies), so by using some large fraction of a star's energy this should be possible.

We're not far from having the telescope technology that enables us to spectrally sample the atmospheres of extrasolar planets to detect gases that are associated with life (as we know it) and even of technological civilizations (e.g. chlorofluorocarbons). This is a form of SETI too. Using such technology, an alien civilization could beam signals to selected planets that show such signs and save the energy of broadcasting omnidirectionally.

The purpose of SETI is not necessarily to confirm such possibilities (my opinion is that civilizations like us are really rare at this stage of the Universe's evolution - maybe less than one per galaxy). But at least to rule them out.

It's always worth remembering that O(n) describes the asymptotic limit where n is presumed to be very large (in fact, approaching infinity).

50 light years is the generally accepted distance that would cause problems. There are no candidates this close that could cause a type II supernova (this is when a massive old star, like Betelgeuse, collapses), but there could be potential type I supernovae lurking closer. These are binary pairs of a white dwarf and another star where the white dwarf is accreting mass from the companion and reaches a limit (the Chandrasekhar mass) where runaway nuclear fusion spontaneously occurs.

Imagine some water freezing. This will often start from a nucleation point and spread out rapidly. If this hits another volume of water nearby that's doing the same thing, you might get a crack in the ice where they hit each other. This is kind of what cosmic strings are. As the universe is cooling and quantum fields undergo phase changes, various regions will spread out and the point where they collide can form a cosmic string. (This is all very theoretical and my explanation is rather vague and handwavy).

50 nmol/l (20 ng/ml) is right in the middle of the 'insufficient' range. Did you mean ng/ml? The upper limit for most labs is between 175 and 200 nmol/l.

In my personal example, taking about 6000 UI (plus 300 mcg K2) for a year put me just under 200 nmol/l. I did an experiment and stopped taking it for 2 months (but kept taking K2). After testing again I had dropped to 70 nmol/l (top of the insufficient range) and had mild symptoms of muscle ache and fatigue. Needless to say, I've started taking it again (and will aim for 175 nmol/l).