Today I Learned

[OmCheeto]

TIL that Graneledone boreopacifica, an octopus, has the longest egg-brooding in the animal kingdom at 53 months.
It is also the longest living octopus.
The female that broods the eggs does not eat the entire time, nearly 4 1/2 years!

I also learned that the incubation time for octopus eggs is temperature dependent, with colder temperatures yielding longer brood times: ref

examples:
3°C = 1600 days, the aforementioned
7°C = 420 days
22°C = 60 days
28°C = 19 days

 

[haushofer]

TIL that if you place two small marbles of 1 kg in interstellar space at 1 meter apart, they will collide after roughly one day due to their gravitational interaction. And that this collision time is another striking example of how a derivation based on units and some thought (2 body problem) can save you from doing a nasty integral.

A resemblance of gravity's weakness, I suppose. You only need to put 10^-10 Coulomb of charge on each marble to get the same collision time due to the electric force (shielding off gravity).

 

[Swamp Thing]

TIL that if you place two small marbles of 1 kg in interstellar space at 1 meter apart, they will colllide after roughly one day...

Just off the top of my head, not actually calculating anything, I would have guessed a time scale of years.

 

[haushofer]

Just off the top of my head, not actually calculating anything, I would have guessed a time scale of years.

I had a similar intuition. I guess a PhD in classical/quantum gravity doesn't guarantee a solid intuition about the subject :P

 

[jtbell]

Today I learned about the city of Peculiar, Missouri: Where the 'odds' are with you.

Wikpedia

Official website

 

[fresh_42]

Today I learned why there is a bite missing on Apple's apple.

 

[pinball1970]

Today I learned why there is a bite missing on Apple's apple.

Is that the Turing thing? I thought that was an urban myth?

 

[fresh_42]

Is that the Turing thing? I thought that was an urban myth?

Well, that's why I didn't mention it. My source wasn't reliable. This is one of the things I like to quote someone who answered an anecdote I told him:

"I don't think it is true. However, the charm of the story is, that it could be true." (Brooks Ferebee)

 

[pinball1970]

Well, that's why I didn't mention it. My source wasn't reliable. This is one of the things I like to quote someone who answered an anecdote I told him:

"I don't think it is true. However, the charm of the story is, that it could be true." (Brooks Ferebee)

I quick search is fuzzy. The fruit seems a bit hippie (fruitarian, commune stuff) and the bite to show it's bigger than a cherry.
Steve Jobs on hearing the Turing story said he wished it was true. Apparently.
So apple = set, fruit
Bigger than cherry
Apple minus bite implies Turing

Code written all over it

 

[collinsmark]

TIL that if you place two small marbles of 1 kg in interstellar space at 1 meter apart, they will collide after roughly one day due to their gravitational interaction. And that this collision time is another striking example of how a derivation based on units and some thought (2 body problem) can save you from doing a nasty integral.

I just did the nasty integral* and came up with 26.7 hours.

*(Wolfram alpha helped. I also assumed the marbles were very dense, such that their diameters << 1 meter.)

 

[DeBangis21]

Today I learned that, in a biology lecture, leech is used in surgery, thus its name.

 

[pinball1970]

TIL: Meteor showers are caused by the earth’s orbit passing through debris left over from a comets trail.

What did I think caused it before? I don’t know is the honest answer, I just thought material hit the earth all the time.

I did not consider that showers are predicted.

https://www.skyatnightmagazine.com/advice/skills/meteor-showers-how-observe-record-shooting-stars/

 

[sophiecentaur]

I just did the nasty integral* and came up with 26.7 hours.

*(Wolfram alpha helped. I also assumed the marbles were very dense, such that their diameters << 1 meter.)

Very much on the same lines, take a spherical asteroid (or rock) with the equivalent density to Earth. Put it out on its own in space and set a small stone in low orbit round it. The orbital period will be around 90 minutes; same as an Earth satellite.
I look forward to someone doing that demo. Come on, Elon!!!

 

[sophiecentaur]

TIL: Meteor showers are caused by the earth’s orbit passing through debris left over from a comets trail.

What did I think caused it before? I don’t know is the honest answer, I just thought material hit the earth all the time.

I did not consider that showers are predicted.

https://www.skyatnightmagazine.com/advice/skills/meteor-showers-how-observe-record-shooting-stars/

it's interesting that a piece of ejecta from a comet is given just one burst of impulse as it leaves. It will have a new, different value of momentum when it leaves and will take up a different solar orbit (assuming it has greater than escape velocity from the comet). Orbital mechanics says that the piece's new orbit will re-visit the place where it left the comet (just the same as when satellites transfer orbits). It won't arrive at the same time as the comet's next time round but the piece, along with all the other ejected pieces will arrive back on the path of the comet and go through it. So, iirc, that means there is a focussing effect on all parts of the ejecta such that they will all turn up in a given belt, again and again. When earth passes through this belt, you will get a 'shower' of them; They don't just disperse all over the Solar System.

I'm not sure how many comets repeat their solar orbits closely enough for each pass to leave junk along the same track.

 

[pinball1970]

TIL what a sea mount is, https://en.wikipedia.org/wiki/Seamount

 

[pinball1970]

TIL More stuff about the sinking of the Titanic. @hagopbul and @russ_watters mentioned the subject for a possible Engineering thread so this is worth a mention if not an actual thread.
Titanic is very interesting, very tragic and had so many bad luck points associated with it. Worth a thread in the History forum.

There is also information regarding the design of the bulk heads, the iron grade used in the rivets, a fire in the coal store and the angle she hit the iceberg that would interest the engineers?

Anyway, this is a minute by minute animation but there is also a minute by minute animation with commentary on YouTube done on the anniversary. Very interesting and a lot of research went into it. "Titanic Honour and Glory." (Three hours 45 mins, I watched all, fantastic)

Anyway here is the link to the former. (No torpedoes....)

 

[Grelbr42]

TIL that the now-deprecated practice of the dunce cap arose from insults directed at a person named Duns Scotus. https://en.wikipedia.org/wiki/Duns_Scotus https://en.wikipedia.org/wiki/Dunce

Duns Scotus was

 

[BillTre]

TIL that there are people who crochet animals:

 

[Ibix]

Love the dopey grin on the angler fish...

 

[hagopbul]

Really that was I meant it is a very interested engineering question, I should not mention the sea projectil

 

[phinds]

Really that was I meant it is a very interested engineering question, I should not mention the sea projectil

? what are you talking about?

 

[hagopbul]

Concerning @pinball1970

 

[phinds]

Concerning @pinball1970

Well, please learn to quote the post you are responding to so it's clear what you are talking about.

 

[hagopbul]

Concurring @pinball1970

 

[pinball1970]

TIL "A blackened, broken leg bone from Earth’s prehistoric past may hold the answer to when early humans diverged from apes and started their own evolutionary path."

From Last August- paper in Nature. I will check no thread on it and post

 

[DeBangis21]

Today, at this moment, I learned that cockroaches can cause infectious intestinal diseases viz: cholera, diarrhea, typhoid fever, etc. Also allergic.

 

[symbolipoint]

Today I learned that, in a biology lecture, leech is used in surgery, thus its name.

Still a current method or treatment today? Me, not sure, but I may not be well-informed. Today wound debridement therapy using maggots does exist; special care taken in rearing the young maggots.

edit: (excuse me for editing this. I forgot about the word, "maggot" so used the misspelled larva instead.)

 

[berkeman]

Still a current method or treatment today? Me, not sure, but I may not be well-informed. Today wound debridement therapy using larvas does exist; special care taken in rearing the young larvas.

Lordy,I had no idea.

[Warning, do not click into this following link unless you are a medical professional, or seriously deranged]

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

 

[Bystander]

Lordy,I had no idea.

[Warning, do not click into this following link unless you are a medical professional, or seriously deranged]

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

You really have led a sheltered life, haven't you...leeches(?), maggots..."lions, tigers, and bears, oh my...."

 

[Astronuc]

Lordy,I had no idea.

[Warning, do not click into this following link unless you are a medical professional, or seriously deranged]

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

I've heard about that - using 'clean' maggots.

I've heard about injured POWs who used maggots to debride their wounds of necrotic tissue, then urinated on them to kill them when they finished clearing the dead tissue and to start the healing. I believe leaches are used because they have anticoagulants, which aids in blood flow and prevents gangrene.