Category Archives: science

Supernovae

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I went (via Zoom) to a great lecture last night. Serafina Nance spoke to the The Calgary Centre of the Royal Astronomical Society of Canada on Tracing the Lives, Deaths, and Explosions of Massive Stars.

Supernovae are cosmic events of gigantic power. Their explosions can shine as bright as a galaxy, a pinprick of extraordinarily bright light in the night sky. What is less well-understood, however, is which stars reach the point of explosion and how they evolve to their deaths. Interestingly, their explosions provide astronomers with key tools to uncover fundamental aspects of our Universe. While we know that the Universe is expanding at an accelerated rate due to dark energy, the rate of the expansion of the Universe is not well-constrained. Supernovae provide us with independent ways to measure this expansion and work to resolve one of the most pivotal questions in astronomy: How fast is the Universe really expanding?
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Significant Figures

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I found this post on Facebook: Why is it important to know so many digits of pi?.

My comment:

As someone who started computing with log tables and slide rules, the first question I ask is how many significant digits do the other variables in your calculation have? The smallest such number tells you how many digits of pi you need. With electronic devices there is no harm in using more in your calculation, as many as your device has, but do not let that give you a false idea of the precision of your result.

I learned about significant figures in my high school chemistry in 1967-68. (Thank you, Mr. Wheeler!). Use of appropriate significant figures, also from a chemistry class, clearly explains the concept and its use in practice.

I only first saw Star Trek (TOS) after high school, in reruns. Thanks to that chemistry class I gag every time I hear Mr. Spock reporting some calculation to an absurd number of decimal places. His input data could not possibly be that precise!

Water on the Moon

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It’s confirmed. There is water on the Moon. OK, what’s the big deal? Water is very common in the cosmos and has been seen on the moon before. The difference is that previously it had been been only in craters near the lunar south pole, perpetually in darkness. Now, as the updated NASA announcement said, NASA’s SOFIA Discovers Water on Sunlit Surface of Moon, which will be much more accessible to future explorers.

How significant this is remains to be seen, but it has provided Katie Mack with some inspiration.

Phosphine on Venus: Not so fast

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Last month I posted about a Possible Sign of Life on Venus, which reported on Phosphine gas in the cloud decks of Venus. Earlier this month I mentioned More about phosphine on Venus. The story is not over yet.

A Question of Phosphine links to Re-analysis of the 267-GHz ALMA observations of Venus: No statistically significant detection of phosphine. This team re-analyzed the same data used in the first Phosphine gas paper, but came to the opposite conclusion. So it comes down to a very complicated question of statistical analysis.

Professor Coles also linked to A stringent upper limit of the PH3 abundance at the cloud top of Venus by another team which included Jane Greaves, first author of Phosphine gas in the cloud decks of Venus.

American Poison Gas in World War II

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During World War II the United States was prepared to use poison gas against the German army. 100 tons of mustard gas were shipped to the port of Bari in southern Italy, held by the Allies and far behind the front lines, on the ammunition ship John Harvey. Being an ammunition ship, the John Harvey also carried a full load of conventional explosive munitions. Disaster At Bari tells the story of how, on the night of December 2, 1943, the port of Bari was attacked by 105 Ju 88 Luftwaffe bombers. The attackers achieved complete surprise: the Allied high command did not think the Luftwaffe was still capable of a raid this far behind the front lines. The lights were on in the harbor so that unloading the docked ships could continue during the night. The Luftwaffe pilots and bombardiers made good use of this, and sank 17 cargo and transport ships, with 8 others damaged. One of the targets was the John Harvey. As an ammunition ship it blew up in a huge explosion, spreading mustard gas all around.

Hundreds of victims were taken to hospitals with strange symptoms. Many died and the medical staff had no idea why. The presence of mustard gas on the John Harvey was a closely guarded secret. Eventually a senior medical officer was flown in from Allied headquarters in Algiers. He quickly realized that the men had been exposed to mustard gas. With some difficulty, he was able find out that the John Harvey had mustard gas in its cargo. There 617 military and merchant marine mustard-gas casualities that night. 84 men died. No one knows about the casualties among the Italian civilians. Many lives could have been saved if the presence of mustard gas had been known immediately and proper treatment administered to the victims.

Evidence for Literacy in Ancient Judah

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The Babylonians sacked Jerusalem and conquered the biblical kingdom of Judah in 587 BCE. Just before then, c. 600 BCE, Judah maintained a small military outpost at Tel Arad, about 20 miles south of Jerusalem. Written inscriptions have been found there on ostraca (pottery fragments), a common writing medium in the ancient world. The fort at Tel Arad was a small place, with a garrison of 20-30 soldiers. Yet a handwriting analysis of 18 incriptions shows that there were least 6 and perhaps as many as 12 authors of these texts. This indicates that literacy was not uncommon in Judah at the time, at least among the army. It was not the exclusive domain a few scribes serving the king.

Given a substantial degree of literacy, it is plausible that some of the books of the Hebrew Bible, e.g. Deuteronomy, Joshua, Judges, Samuel, and Kings, were in fact written down before the fall of Jerusalem and the Babylonian exile.


References

More about phosphine on Venus

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Following up on Possible Sign of Life on Venus. After that announcement some scientists took another look at 1978 data from the Pioneer Venus Multiprobe. At the time nobody was specifically looking for phosphine, but a new analysis of the raw data supports the possibility that there is phospine in the atmosphere of Venus. Details at Is Phosphine in the Mass Spectra from Venus’ Clouds?.

This has happened before in astronomy. After both Neptune and Pluto were discovered, astronomers looked at old records and found that their predecessors had seen both bodies, but had not realized they were significant. In the case of Neptune one of those predecessors was Galileo.

Possible Sign of Life on Venus

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Yesterday I got an email from Cosmoquest about a science press conference (“presser”) where a new discovery would be announced. With all the new distance-based communication technology anybody could watch, rather than just those in a select room, however large. The event was put on by the Royal Astronomical Society today. I watched it on the Cosmoquest Twitch TV channel. I had never heard of Twitch TV before.

The occasion was that

An international team of astronomers, led by Professor Jane Greaves of Cardiff University, today announced the discovery of a rare molecule – phosphine – in the clouds of Venus. On Earth, this gas is only made industrially, or by microbes that thrive in oxygen-free environments.

The discovery was made by spectroscopy using two different radio telescopes. The significance of this is that the production of phospine by purely chemical processes is very unlikely in the atmosphere of Venus. The team looked at every possible chemical reaction they could think up, and failed to find any that could come close to producing the observed amount of phospine.

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Free the Quarks!

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Calculating the strong force

A watershed: the emergence of QCD

We had arrived at a very specific candidate theory of the strong interaction, one based on precise, beautiful equations. And we had specific, quantitative proposals for testing it.

See also the Bag Model of Quark Confinement. Corry Lee gave a great explanation of this in her talk about the Higgs Boson at Chicon 7 last summer.

Statistics Hell

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From Andy Field.

You hate statistics, you despise maths, you stain your pants at the mention of sphericity. Normal people love these things, but you, barrel of number-fearing sputum that you are, are terrified. Afraid for your worthless life you leapt pathetically to the internet for guidance. A freak spark of lightening hit your house sending a bolt of electricity through your computer. Sparks flew like tendrils from the screen, fusing with your face and sucking your head and body into the number vortex that is statistics hell. Your crime is evacuating your bowels at the mention of a t-test, your punishment is eternity in statistics hell. I am the gatekeeper, the evil ruler of this world of numbers. Although you might confuse me for a human full of empathy and compassion for those taking their first wobbly steps through this horrific world of equations, underneath my skin I am numbers without a soul.