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Comment by rwcarlsen | Hacker News Reader

This reminds me of the desirability of pre-WWII battleship steel in particle physics experiments. Due to required detection sensitivity they need to construct experiments from materials that have as low background radiation as possible in order to not mask the actual information of interest. Ever since the first atomic bombs were detonated, sufficiently low-radioactivity steel became much more difficult to find. A large portion of available low-background steel supply is from battleships that were built before the bombs [1]

[1] https://en.wikipedia.org/wiki/Low-background_steel

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Note that there is a similar particle-physics demand for lead from Roman-Empire warships ("ancient lead"). But in that case, it doesn't have anything to do with anthropogenic radiation. Rather, lead that is in the ground is constantly kept slightly radioactivate by background decays. But lead that has been pulled out of the ground and allowed to sit unmolested for a thousand years will deactivate.

The popular coverage:

https://www.scientificamerican.com/article/ancient-roman-lea...

I saw a talk on one of these experiments while I was a grad student. Apparently their lead source had "historical significance" according to the government of France, and getting it out of the country required beurocratic maneuvers of questionanable legality.

The real shame is that ancient lead isn't the only alternative, just the cheapest. Lead could be spun in centrifuges and then securely cast to remove such contaminants. This has been done with silicon, in that case to remove unwanted isotopes. It is a wildly expensive process but at least it is a process that could produce an infinite amount of product, rather than ancient lead of finite supply.

Huh. Basically like uranium?

But what compound? PbH4 isn't stable. PbF4 is barely stable. Maybe Pb(CH4)4 ??? Naively, I guess that you'd get even better mass resolution. Molectual mass of UF6 being ~352, vs ~267 for Pb(CH4)4. Good use for all those leftover centrifuges ;)

Or maybe even with just liquid lead? Would need very different machines but might be possible.

> a process that could produce an infinite amount of product

Well, it would be infinite until you run out.

Edit: it appears that someone disagrees with me. No worries, healthy disagreement is a good thing.

But I'm curious: how would you produce an infinite amount of product?

You're getting downvoted because you're nitpicking vocabulary. Most people understood "infinite amount of product" to mean "functionally infinite, given the low demand and large supply."

You are no doubt correct.

I won't worry about it further, time to go enjoy my unlimited internet.

The presence of Cesium-137 and Strontium-90 has also been used to reveal art forgeries. Before atomic bombs were tested, these isotopes did not exist in nature. Art produced before 1945 will not contain these isotopes, while art produced after that time usually will.

How does this work? The old art still exists but how does it avoid exposure? Why is exposure only relevant at the time of creation? Will old paint used in modern times display the isotope?

Traces of the isotopes in question are detectable in the pigments used in recently produced art. Surface contamination isn't what's being tested.

The issue is usually in contamination of raw materials.

Similar to carbon-14 dating - the isotopic ratio of carbon in the atmosphere is maintained by cosmic radiation hitting the carbon-12 and carbon-13 atoms, but as soon as the carbon is incorporated into solid matter it ceases to be part of the process that renews the carbon-14 levels.

And one source for this steel is courtesy to Admiral von Reuter who managed to scuttle his fleet, guarded by the Brits and interned in the Orkney archipelago, in June 1919. Better to sink that serve the enemy, right?

https://en.wikipedia.org/wiki/Scuttling_of_the_German_fleet_...

A bit nicer than having the British attack an allied fleet because they might capitulate to the Germans: https://en.wikipedia.org/wiki/Attack_on_Mers-el-K%C3%A9bir

In Britain's defence, the Germans did later try to capture the remnants of the French fleet, and the French scuttled their fleet to avoid capture: https://en.wikipedia.org/wiki/Scuttling_of_the_French_fleet_...

Another interesting story involving the scuttling of a ship is the Battle of the River Plate (https://en.wikipedia.org/wiki/Battle_of_the_River_Plate). The German ship, the Admiral Graf Spee, was forced into a neutral port due to damage. Rather than be forced out to face an overwhelming force they were certain to lose against, Captain Langsdorff instead scuttled the ship and committed suicide.

I couldn't find a straight answer to this the last time I looked, but it sounds to me like this is more of a matter of cost then the actual hard need for pre-WWII steel.

We could mine ore that hasn't been exposed to the atmosphere since then, and use air (either purified or found in some air pockets underground) for the furnace behind an airlock.

This would be much more expensive than just finding some pre-WWII steel, there's a lot of that around, but I don't think it's the case that if we somehow didn't have it we'd be screwed.

Am I wrong?

Wow, I hadn't realized the effects of the atomic age were that widespread, creepy.

You should make the opposite conclusion. The fact that atoms are so tiny that almost every notable event has a detectable affect on isotope ratios means you should downgrade the meaningfulness of the OP article. (See my other comment on ancient lead, which has nothing to do with nuclear tech.) Likewise, when seizmic technology improves and we can sense explosions from further away, we don't conclude that building demolition is somehow more important than we previously thought.

Yeah, a similar observation is that there are more atoms in a glass of water than glasses of water in all the oceans. So, dumping a glass of (somehow trackable) water into the ocean would eventually cause every glass of water to contain atoms from that glass. See also: http://samkean.com/books/caesars-last-breath/

Or it takes 10 years for one of your breaths to be spread around the atmosphere, and everyone is very likely to be breathing at least one molecule of that breath in every breath they take.

From article "Breathing Everyone's Air" - scroll down to that heading in http://www.scifun.ed.ac.uk/card/facts.html

Take a look at this friendly graph of carbon-14 concentration in the atmosphere since 1955 for just one example: https://en.m.wikipedia.org/wiki/Carbon-14#/media/File%3ARadi...

Just note that this friendly graph employs the bad practice of not having the vertical axis origin at 0, which visually exaggerates the change.

I disagree. It's a multiplicative factor vertically centered to 1. Seems better to me than if it had been aligned to 0.

Not necessarily a bad practice. Most of the graphs I've seen use this technique, do so to make the changes in value visible, not to deceive the viewer.

If the change is invisible on a 0-based graph, maybe the change isn’t so important....

This one only exaggerates things by a factor of 2, at least.

Doubling is pretty significant, as is the rate of increase prior to, and dropoff after, 1963.

If some sort of catastrophe befalls our current civilization and future archaeologists attempt to C14 date our fossils and artifacts derived from carbon sequestered during this era, their results will be wildly unreliable.

There are many important changes that are hard to see on a 0-based graph.

If you plot human body temperature in Kelvins, the difference between someone with hypothermia and someone with a raging fever are relatively slight (under 2%).

0 is only relevant for linear utility/impact functions The effect of an isotope isn't necessarily linear in its magnitude from 0. The baseline should be something that matters, like maximum safe dose.

If you have a baseline and a scale that indicates an actual effect, then by all means use it. That’s not the case here, nor has it been the case for any other such graph I can remember seeing. Universally, the bottom is chosen as the minimum value in the data being plotted.

Climate change is significant, even though I'm certain that temperature charted against 0 Kelvin isn't too visible.

Zero can be just as arbitrary a starting point as non-zero.

The cosmic microwave background is invisible on a 0-based image.

Only if you’re trying to show the CMB and galaxies in the same image. Since doing so would be misleading as to the brightness of the CMB, that seems like a feature, not a bug.

No, if you insist on a uniform colormap that includes 0K (or whatever measurement you're showing the CMB with) then there's absolutely no way to make the CMB visible. The average temperature is 2.72548 K with variations on the order of 0.00057 K. Its incredible uniformity is one of its more important features.

Oh, you meant variations in the CMB. I thought you just meant making the CMB visible.

That's just it: if the changes are only visible if you chop off the bottom of the graph, the probability they aren't significant increases.

How would you feel if your body temperature increased 3%? Barely visible in a 0-based graph.

What is a 3% change in body temperature? From absolute zero?

(My point is that temperature is probably an odd man out in graph terms, our usual reference points are not actually at zero.)

Check out Caesar's Last Breath: Decoding the Secrets of the Air Around Us by Sam Kean.

Far less interesting a read, an article about how many molecules of Beyonce's breath you inhale with each breath. https://www.huffingtonpost.com/2014/12/12/beyonce-breath_n_6...

A paleontologist friend of mine often quips that in his field, everything from the 1950s onward is considered “present date”, because the additional radiation pretty much ruined any chance of accurate carbon dating after the atmospheric testing era.

Granted, paleontology looks back in the span of millions to billions of years, so those ancient fossils are ok, but I imagine future scientists will grind their teeth an awful lot when trying to make scientific sense of our present day.

Maybe they’ll love having a really obvious marker that they can definitively date to almost the exact year.

Merely by breathing for a year, everyone in the world inhales a measureable amount of radiation from atmospheric tests performed in the 1950s.

check out this graph of radioactive cesium in mother's milk

http://webarchive.nationalarchives.gov.uk/20130403200836/htt...

Chernobyl is just a tiny blip.

Just about every living thing that has lived since 1945 has had tracers of the atomic age within its body, in the form of isotopes that were far less common, prior to atmospheric nuclear tests.

Another chemical effect of the modern age:

Before the industrial revolution, silver did not tarnish. Burning coal introduced enough sulfur in the air that silver started tarnishing.

This struck me as very surprising. Straight Dope's take[1]:

> While coal-burning power plants are responsible for producing most of the sulfur dioxide out there (and thus acid rain), they don’t contribute that much of the compounds that actually cause silver to tarnish, namely hydrogen sulfide—best known as a key player in the smell of rotten eggs and flatulence—and the similarly pungent carbonyl sulfide. About 90 percent of the hydrogen sulfide and more than two-thirds of the carbonyl sulfide in our atmosphere come from (you guessed it) volcanoes, salt marshland, undersea vents, and other natural sources.

[1] https://www.washingtoncitypaper.com/columns/straight-dope/ar...

> more than two-thirds of the carbonyl sulfide in our atmosphere come from (you guessed it)

And here I thought they were going to say rotten eggs and flatulence...

Is there a reason they can't smelt it from fresh ore and carbon?

The process of creating steel requires heating it with coke in a large furnace. A large volume of atmospheric air is pumped into the furnace, and it is this atmospheric air that introduces the radioactive particles to the mix.

There are vacuum furnaces that lack this atmospheric air, but their process is much more expensive.

Heating it with Coke?

https://en.m.wikipedia.org/wiki/Coke_(fuel)

Delicious Coca-Cola (tm) </s>

The link explains that it’s due to the atmospheric air used in the process.

> From 1856 until the mid 20th century, steel was produced in the Bessemer process where air was forced into Bessemer converters converting the pig iron into steel. By the mid-20th century, many steelworks had switched to the BOS process which uses pure oxygen instead of air. However as both processes use atmospheric gas, they are susceptible to contamination from airborne particulates. Present-day air carries radionuclides, such as cobalt-60, which are deposited into the steel giving it a weak radioactive signature.

From https://en.wikipedia.org/wiki/Low-background_steel

the isotopes from the air would contaminate it.

Forgive my ignorance as I really don't know anything about this but would it not be possible, when using post WW2 steel, to take before and after readings and diff them?

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