6 ms·

2000 year old Roman lead used for physics

wenbert 10y ago
Off-topic: I love reading articles that use 2-column format. I think it should be done more often. Although I wished the font would have been a "seriffed" one.
- treve 10y ago
  I think it's a bit weird to have to scroll down and up again. Doesn't make a ton of sense to me, especially if the article gets really long. In this particular case it's also not responsive, which makes it a pretty bad experience on mobile. I would be curious if there's a good version of a 2-column layout; but I don't think this is it.
- ams6110 10y ago
  It's a good format for a printed article. Not so great on a screen.
- rangibaby 10y ago
  Not sure about the down votes here. I think columns are acceptable in digital as long as they are responsive (e.g. 1 column mobile, 2 column normal, 3 column wide). Why columns? Good-length columns minimize your eye movement and make it less tiring to read. More than about 10 words per line require you to move your eyes too much horizontally or vertically and you can lose a train of thought etc.
  - freshyill 10y ago
    That's fine if you can guarantee the user won't have to scroll up and down to read the content. If you can't guarantee that, then the designer is just forcing a print convention where it doesn't belong. The solution is to make a narrower column.
    - rangibaby 10y ago
      > That's fine if you can guarantee the user won't have to scroll up and down to read the content. Agreed. I consider Bootstrap's default breakpoints to be fairly trustworthy in the regard.
  - flukus 10y ago
    > Not sure about the down votes here. I think columns are acceptable in digital as long as they are responsive (e.g. 1 column mobile, 2 column normal, 3 column wide). Which is not the case here. Resizing the browser keeps the same number of columns.
    - rangibaby 10y ago
      I meant in the general case of course. This specific site design, which appears to be from the early 2000s, is older than phones using the "real" internet so perhaps you can forgive them for not making a responsive website.
- kbart 10y ago
  I hate 2-column format on screen, so I guess that's a matter of taste. Printed is ok though, maybe because you generally keep paper closer to your eyes than screen.
yodon 10y ago
I hope they are careful with the lead. When I was in grad school, there were still memories of a similarly large supply of low-radiation lead salvaged from a similar ship wreck that ended up being stolen for recycling as scrap (I remember hearing this lesson when I was at Princeton, which I believe is where the the theft happened) Just because physicists consider the lead invaluable and irreplaceable doesn't mean recycling thieves will feel the same level of reverence towards it.
- ams6110 10y ago
  What causes "new" lead (whatever that means) to be more radioactive? I mean, there's nothing really creating lead naturally in the environment, so isn't all lead pretty much the same age?
  - deleted 10y ago
    [deleted]
  - jpt4 10y ago
    Atmospheric nuclear detonations have contaminated all un-so-shielded metals: https://en.m.wikipedia.org/wiki/Low-background_steel https://en.m.wikipedia.org/wiki/Low-background_steel
  - anamexis 10y ago
    I assume it is for the same reason as with steel[1] - the refinement process involves atmospheric air, and after we started detonating nuclear bombs, we raised the background radiation level of the atmosphere, and thus of the metals we produce. [1] https://en.wikipedia.org/wiki/Low-background_steel https://en.wikipedia.org/wiki/Low-background_steel
  - peterburkimsher 10y ago
    There's a longer article explaining about Low-Background Steel on Hackaday: http://hackaday.com/2017/03/27/low-background-steel-so-hot-right-now/ http://hackaday.com/2017/03/27/low-background-steel-so-hot-r...
  - ISL 10y ago
amexrap 10y ago
Submitted 5 years ago: https://www.reddit.com/r/todayilearned/comments/pg14g/til_that_ancient_roman_lead_is_valuable_for/ https://www.reddit.com/r/todayilearned/comments/pg14g/til_th...
- IshKebab 10y ago
  This has been submitted now because Hackaday posted an article today about low background steel, and it mentioned the use of ancient Roman lead: http://hackaday.com/2017/03/27/low-background-steel-so-hot-right-now/ http://hackaday.com/2017/03/27/low-background-steel-so-hot-r...
Safety1stClyde 10y ago
I didn't see this in the article, but is it correct to think that if the isotope decays after 23 years, the reason that natural lead contains it is because natural lead itself is some kind of decay product.
- unlikelymordant 10y ago
  Yep, the isotope is constantly replenished by decay of heavier atoms. When it is mined these heavier atoms are removed. You just have to wait for the radioactive isotopes to decay.
- JorgeGT 10y ago
  The isotope in question (Lead-210) is indeed a decay product of Uranium-238. However, not all lead is Pb-210, most of it is made of other, stable isotopes. Since mining and refining lead removes the U-238 that would decay into more Pb-210, if you wait long enough (and shield it underwater), you get almost radiation-free lead, as the Pb-210 existing at the time of mining/refining eventually decays into non-radioactive Pb-206.
carlob 10y ago
I remember visiting the Gran Sasso Laboratories during a high school trip (my high school physics teacher had practiced particle physics for a bit before teaching). It was really one of the defining moments as a student, one of the things that led (no pun intended) me to study physics later.
JetSetWilly 10y ago
One thing I don't understand. Surely the lead atoms are much older than 2000 years - it is not like the Romans "created" the lead via nuclear fusion. The lead atoms must date back to the formation of the earth and beyond. Therefore, the Romans merely concentrated these lead atoms into one place. But why hadn't all the unstable lead atoms decayed already long before? Why does it matter if the lead ingot is ancient or not, the actual lead matter is very ancient regardless?
- carlob 10y ago
  Lead that has just been dug out of the earth was exposed to radiation from other minerals and cosmic radiation until very recently. On the other hand this batch of ancient lead was at the bottom of a lake for 2000 years, so it had time to lose some of its radioactivity while being shielded by water.
- flashman 10y ago
  Pb-210 is a lead isotope that's a byproduct of uranium decay. When mined, all lead contains some Pb-210 as a result of U238 decay[0]. The lead can be refined to remove the U238, but not to remove Pb-210. So all 'fresh' lead contains some Pb-210 with a half-life of 22 years. If you use this for shielding in your experiment, you have to deal with its natural radioactivity. (Now, what confuses me is how the Romans removed U238 from lead, because they must have done so in order to end up with lead that could decay over 2000 years. Maybe it happened as part of the smelting process.) [0]https://www.scientificamerican.com/article/ancient-roman-lead-physics-archaeology-controversy/ https://www.scientificamerican.com/article/ancient-roman-lea...
  - jacquesm 10y ago
    Most old lead objects are cast, casting is a process where a liquid is poured into a mold where it is left to solidify. Presumably because both the melting crucible and the cast are under the influence of gravity while the metal is in the liquid phase the heavier elements will sort themselves to one end of the end-product, maybe even into the flues that will get cut off from the final product. It would be much harder to keep the U238 evenly distributed throughout the lead during such a process.

Off-topic: I love reading articles that use 2-column format. I think it should be done more often. Although I wished the font would have been a "seriffed" one.

treve 10y ago
I think it's a bit weird to have to scroll down and up again. Doesn't make a ton of sense to me, especially if the article gets really long. In this particular case it's also not responsive, which makes it a pretty bad experience on mobile. I would be curious if there's a good version of a 2-column layout; but I don't think this is it.
ams6110 10y ago
It's a good format for a printed article. Not so great on a screen.
rangibaby 10y ago
Not sure about the down votes here. I think columns are acceptable in digital as long as they are responsive (e.g. 1 column mobile, 2 column normal, 3 column wide). Why columns? Good-length columns minimize your eye movement and make it less tiring to read. More than about 10 words per line require you to move your eyes too much horizontally or vertically and you can lose a train of thought etc.
- freshyill 10y ago
  That's fine if you can guarantee the user won't have to scroll up and down to read the content. If you can't guarantee that, then the designer is just forcing a print convention where it doesn't belong. The solution is to make a narrower column.
  - rangibaby 10y ago
    > That's fine if you can guarantee the user won't have to scroll up and down to read the content. Agreed. I consider Bootstrap's default breakpoints to be fairly trustworthy in the regard.
- flukus 10y ago
  > Not sure about the down votes here. I think columns are acceptable in digital as long as they are responsive (e.g. 1 column mobile, 2 column normal, 3 column wide). Which is not the case here. Resizing the browser keeps the same number of columns.
  - rangibaby 10y ago
    I meant in the general case of course. This specific site design, which appears to be from the early 2000s, is older than phones using the "real" internet so perhaps you can forgive them for not making a responsive website.
kbart 10y ago
I hate 2-column format on screen, so I guess that's a matter of taste. Printed is ok though, maybe because you generally keep paper closer to your eyes than screen.

yodon 10y ago

I hope they are careful with the lead. When I was in grad school, there were still memories of a similarly large supply of low-radiation lead salvaged from a similar ship wreck that ended up being stolen for recycling as scrap (I remember hearing this lesson when I was at Princeton, which I believe is where the the theft happened) Just because physicists consider the lead invaluable and irreplaceable doesn't mean recycling thieves will feel the same level of reverence towards it.

ams6110 10y ago
What causes "new" lead (whatever that means) to be more radioactive? I mean, there's nothing really creating lead naturally in the environment, so isn't all lead pretty much the same age?
- deleted 10y ago
  [deleted]
- jpt4 10y ago
  Atmospheric nuclear detonations have contaminated all un-so-shielded metals: https://en.m.wikipedia.org/wiki/Low-background_steel https://en.m.wikipedia.org/wiki/Low-background_steel
- anamexis 10y ago
  I assume it is for the same reason as with steel[1] - the refinement process involves atmospheric air, and after we started detonating nuclear bombs, we raised the background radiation level of the atmosphere, and thus of the metals we produce. [1] https://en.wikipedia.org/wiki/Low-background_steel https://en.wikipedia.org/wiki/Low-background_steel
- peterburkimsher 10y ago
  There's a longer article explaining about Low-Background Steel on Hackaday: http://hackaday.com/2017/03/27/low-background-steel-so-hot-right-now/ http://hackaday.com/2017/03/27/low-background-steel-so-hot-r...
- ISL 10y ago

amexrap 10y ago

Submitted 5 years ago: https://www.reddit.com/r/todayilearned/comments/pg14g/til_that_ancient_roman_lead_is_valuable_for/ https://www.reddit.com/r/todayilearned/comments/pg14g/til_th...

IshKebab 10y ago
This has been submitted now because Hackaday posted an article today about low background steel, and it mentioned the use of ancient Roman lead: http://hackaday.com/2017/03/27/low-background-steel-so-hot-right-now/ http://hackaday.com/2017/03/27/low-background-steel-so-hot-r...

Safety1stClyde 10y ago

I didn't see this in the article, but is it correct to think that if the isotope decays after 23 years, the reason that natural lead contains it is because natural lead itself is some kind of decay product.

unlikelymordant 10y ago
Yep, the isotope is constantly replenished by decay of heavier atoms. When it is mined these heavier atoms are removed. You just have to wait for the radioactive isotopes to decay.
JorgeGT 10y ago
The isotope in question (Lead-210) is indeed a decay product of Uranium-238. However, not all lead is Pb-210, most of it is made of other, stable isotopes. Since mining and refining lead removes the U-238 that would decay into more Pb-210, if you wait long enough (and shield it underwater), you get almost radiation-free lead, as the Pb-210 existing at the time of mining/refining eventually decays into non-radioactive Pb-206.

carlob 10y ago

I remember visiting the Gran Sasso Laboratories during a high school trip (my high school physics teacher had practiced particle physics for a bit before teaching). It was really one of the defining moments as a student, one of the things that led (no pun intended) me to study physics later.

JetSetWilly 10y ago

One thing I don't understand. Surely the lead atoms are much older than 2000 years - it is not like the Romans "created" the lead via nuclear fusion. The lead atoms must date back to the formation of the earth and beyond. Therefore, the Romans merely concentrated these lead atoms into one place. But why hadn't all the unstable lead atoms decayed already long before? Why does it matter if the lead ingot is ancient or not, the actual lead matter is very ancient regardless?

carlob 10y ago
Lead that has just been dug out of the earth was exposed to radiation from other minerals and cosmic radiation until very recently. On the other hand this batch of ancient lead was at the bottom of a lake for 2000 years, so it had time to lose some of its radioactivity while being shielded by water.
flashman 10y ago
Pb-210 is a lead isotope that's a byproduct of uranium decay. When mined, all lead contains some Pb-210 as a result of U238 decay[0]. The lead can be refined to remove the U238, but not to remove Pb-210. So all 'fresh' lead contains some Pb-210 with a half-life of 22 years. If you use this for shielding in your experiment, you have to deal with its natural radioactivity. (Now, what confuses me is how the Romans removed U238 from lead, because they must have done so in order to end up with lead that could decay over 2000 years. Maybe it happened as part of the smelting process.) [0]https://www.scientificamerican.com/article/ancient-roman-lead-physics-archaeology-controversy/ https://www.scientificamerican.com/article/ancient-roman-lea...
- jacquesm 10y ago
  Most old lead objects are cast, casting is a process where a liquid is poured into a mold where it is left to solidify. Presumably because both the melting crucible and the cast are under the influence of gravity while the metal is in the liquid phase the heavier elements will sort themselves to one end of the end-product, maybe even into the flues that will get cut off from the final product. It would be much harder to keep the U238 evenly distributed throughout the lead during such a process.