13
votes
How did the lighthouse at Pharos work?
Was the ancient Greek pharos light house of ancient Alexandria, Egypt capable of creating light beams like a modern flash light?
No.
Historical descriptions
No one really knows any detail of the ...
- 3,177
9
votes
Accepted
How successfull were Albert Einstein's PhD mentees or children?
Einstein had no PhD students, although he did famously collaborate with junior colleagues on the EPR paradox. He had three children:
Lieserl
Her fate is unclear. She may well have died young, ...
- 725
6
votes
Accepted
Where can I find this paper by Jean Buridan?
On John Buridan's page in the Stanford Encyclopedia of Philosophy, we have the citation:
Buridan, John, 1588 (actually 1518), In Metaphysicen Aristotelis Questiones argutissimae, Paris. Rpr. 1964, ...
- 77.2k
6
votes
After the Mongol Empire fell, did China really turn away from math and physics?
TL;DR
According to Roger Hart [1], this view is widely held but wrong. He cites, among (many) others, Needham who speaks of a decay and Mikami who considers Ming scholars to be degenerate. The alleged ...
5
votes
Newton a plagiarist?
The story with Hooke--Newton correspondence was well-known at the time of Newton.
Newton consciously belittled Hooke's contribution, against the advise of some friends. He also claimed that he had ...
- 38.8k
4
votes
Accepted
Newton a plagiarist?
No. Several people had the idea of an attractive force, and some of them of an inverse square law. Newton worked the idea out in detail, and showed that it produced results that matched the ...
- 32k
4
votes
Does anyone know of any examples of the Magnus effect in a real battle?
Making use of the Magnus effect in the era of round cannonballs fired from unrifled cannon was impractical. The rotation of the ball is caused by minor irregularities on the surface of the ball, and ...
- 32k
4
votes
How did the lighthouse at Pharos work?
To go into more details re. the mirror: Some of your links say that there are reports that the lighthouse had a curved mirror, which could even be used to set ships on fire or to spy on Constantinople ...
- 9,406
2
votes
Today, do we celebrate anniversaries of events that happened in time of Julian calendar, on Julian date or at corresponding Gregorian date?
It depends. One obvious example is the October revolution in Russia, which took place on 7-th of November according to Gregorian calendar, but 25-th of October according to the Julian one, in use in ...
- 4,219
2
votes
Today, do we celebrate anniversaries of events that happened in time of Julian calendar, on Julian date or at corresponding Gregorian date?
Celebrations or remembrances are a social event. Consider, for instance, Catholic and Eastern Orthodox religious calendars. Or the remembrance of VE day, which is one day later in Russia due to time ...
- 17.7k
2
votes
Does anyone know of any examples of the Magnus effect in a real battle?
For firearms the main Magnus effect is on range, in particular the range at which the bullet drops from supersonic to subsonic. (The direction of crosswind relative to orientation of barrel rifling ...
- 72.5k
1
vote
What kind of missile flew with such speed in 1st century BCE?
My guess (and we can really do little more than guess) is that he means lead slingstones. John Reid of the Trimontium Trust did experiments indicating lead shot from a hand-sling can be loosed at ...
- 107
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