The speed of light in vacuum, denoted c, is a physical constant that is
exactly equal to 299,792,458 metres per second (approximately 186,282
miles per second, or one foot per nanosecond). According to standard
modern physics, visible light and all other electromagnetic radiation
moves at this constant speed in vacuum, and c is the fastest speed at
which matter, energy or any signal carrying information can travel
through space. Ole Rømer first demonstrated in 1676 that light does not
travel instantaneously by studying the apparent motion of Jupiter's moon
Io (diagram shown). In an 1865 paper, James Clerk Maxwell proposed that
light was an electromagnetic wave, and therefore travelled at the speed
c. According to the theory of special relativity, which interrelates
space and time, all observers will measure the speed of light as being
the same, regardless of the inertial reference frame of the observer or
the velocity of the object emitting the light.
Read more: <https://en.wikipedia.org/wiki/Speed_of_light>
_______________________________
Today's selected anniversaries:
1942:
The Holocaust: During the deportation of Jews from Slovakia,
President Jozef Tiso gave a speech describing Jews as "parasites" and
"the eternal enemy".
<https://en.wikipedia.org/wiki/Jozef_Tiso%27s_speech_in_Holi%C4%8D>
1945:
The Stanley Internment Camp in Hong Kong was liberated
following the announcement of the surrender of Japan in World War II.
<https://en.wikipedia.org/wiki/Stanley_Internment_Camp>
1962:
The English rock band the Beatles fired their drummer Pete
Best, replacing him with Ringo Starr (pictured).
<https://en.wikipedia.org/wiki/Ringo_Starr>
1986:
Typhoon Wayne formed over the South China Sea, going on to
become one of the longest-lived tropical cyclones in the north-western
Pacific, lasting 21 days.
<https://en.wikipedia.org/wiki/Typhoon_Wayne_%281986%29>
_____________________________
Wiktionary's word of the day:
catapeltic:
1. (military, weaponry, archaic) Pertaining to a catapult or catapults.
2. (military, weaponry, obsolete, rare) A catapult.
<https://en.wiktionary.org/wiki/catapeltic>
___________________________
Wikiquote quote of the day:
Take heed of doing irrevocable acts in thy passion, As the
revealing of secrets, which makes thee a bankrupt for society ever
after: neither do such things which done once are done for ever, so that
no bemoaning can amend them. Sampsons hair grew again, but not his eyes:
Time may restore some losses, others are never to be repaird. Wherefore
in thy rage make no Persian decree which cannot be revers'd or repeald;
but rather Polonian laws which (they say) last but three dayes: Do not
in an instant what an age cannot recompence.
--Thomas Fuller
<https://en.wikiquote.org/wiki/Thomas_Fuller>
Show replies by date