Naked Science Forum
General Science => General Science => Topic started by: Nizzle on 20/08/2009 18:10:36
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Hi all,
I'd like to see a collection of science related fun facts here.
Only one rule: Your fun fact should start with the words "Did you know"
I'll start with an example [:)]
Did you know that the lighter was invented before the matches?
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Did you know you can't lick your elbow?
(great one for keeping kids entertained at parties) [:)]
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Did you know that your bed hosts just around 5 000 000 dustmites just as if it was a jumbo-size hotel?
(Counted them myself)
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Did you know is an anagram of "I'd dunk woody"
http://en.wikipedia.org/wiki/Woody_Woodpecker
Did you know that deer have no gallbladders?
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Did you know if plane was invented thousands year before wright?
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Did you know 22.3% of people can't spell*
*Did you know that 37.6% of statistics are made up on the spot?
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A Goldfish's attention span is three seconds
AND
Animals that lay eggs don't have belly buttons.
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"A Goldfish's attention span is three seconds" is false according to our friend the Bored Chemist.
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Your right here is the correction!
#1 "A goldfish's attention span is three seconds." This theory was tested by Discovery Channel's MythBusters. The experiment consisted of training several goldfish to complete a maze. They concluded that a goldfish's attention span and memory retention lasts well over 3 seconds.
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A "jiffy" is actually 1/100 of a second.
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1 Googol is 1 x 10100
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Did you know that french fries has nothing to do with France?
.. but rather with the verb 'to french' which means 'to cut into slivers or thin strips before cooking'
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Lizards communicate by doing push-ups.
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Did you know that originally Coca-Cola contained milligrams of cocaine.
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You know which letter is not on the Periodic Table?
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You know which letter is not on the Periodic Table?
J
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There you go [:)]
Now we all know
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Is it too late to suggest the symbol for element 112 being 'J'?
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Did you know you can't lick your elbow?
(great one for keeping kids entertained at parties) [:)]
I can lick your elbow !!
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Did you know that just over two years ago a similar thread was created by someone here ? http://www.thenakedscientists.com/forum/index.php?topic=9499.0
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Did up know that the male population of the world is 51.4%.(Fact courtesy of factoids on The Steve Wright show [:I])
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Did up know that the male population of the world is 51.4%.(Fact courtesy of factoids on The Steve Wright show [:I])
The recorded female:male ratio is 100:105 at birth.
I doubt Steve mentioned that infanticide of females is in part responsible for this asymmetry.
In the elderly females outnumber males.
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Did you know you can't prove that the world will still exist after your Death?
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Did you know you can't lick your elbow?
i did once. people were amazed. it took me about an hour.
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You know which letter is not on the Periodic Table?
J
Did you know that old German copies list iodine as Jod with the symbol J?
Did you know that "Q" doesn't apear in the periodic table?
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Did you know that old German copies list iodine as Jod with the symbol J?
Yes. The Danes copied the Germans example. Today the symbol is I, but 'Jod' has still been kept as its name.
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Did you know that most of carrots are orange coloured because of the Dutch (carrots exist in other colours, as white, violet, red, black)?
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Did you know that "Q" doesn't apear in the periodic table?
Just wait 'til we get Uuq...
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Did you know that "Q" doesn't apear in the periodic table?
Just wait 'til we get Uuq...
Q used to be on the Periodic table. It was element 104 (Unq - Unnilquadium), but was renamed Rutherfordium (in the honour of Ernest Rutherford) and is now symbolized by Rf. So depending on which periodic table you use, Q might actually appear [:)] My periodic table from the Navy has it written as Unq.
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Did you know there is no proper name for the back of the knees?
(Reg Smeeton)
(in memoriam Vivian Stanshall and John Peel)
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Did you know the smallest bird is a Hummingbird?
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Did you know? Carrot cannot make your eyes clear.
It's just hoax. British lied to the world if they can fight (war) in the dark night because of their "rabbit eyes". They told if they can made their eyes clear and brighten. Whereas, it's just a radar technology.
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Did you know the hottest temperature ever recorded on Earth was 58 degrees celcius?
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Did you know that some Native American Tribes truly believed that they were dreaming when they were awake, and that the true reality manifested itself in their dreams.
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Did you know people once believed Earth was flat? [:D]
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Did you know that global Oxygen levels are significantly higher during the northern hemisphere's summer months due to thawing of the Siberian Taiga forest?
And
Did you know that 1/3 of all the trees has it's roots in the Siberian Taiga forest?
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Did you know the hottest temperature ever recorded on Earth was 58 degrees celcius?
Whilst (I think) I know what you mean, the statement is clearly cobblers... My thermometer goes much higher [:P]
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Did you know the hottest temperature ever recorded on Earth was 58 degrees celcius?
Whilst (I think) I know what you mean, the statement is clearly cobblers... My thermometer goes much higher [:P]
You leave it in the sun or what? [:D]
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Did you know the hottest temperature ever recorded on Earth was 58 degrees celcius?
Whilst (I think) I know what you mean, the statement is clearly cobblers... My thermometer goes much higher [:P]
Even the one inside of my car... Of course these cases don't count.
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Did you know the hottest temperature ever recorded on Earth was 58 degrees celcius?
Whilst (I think) I know what you mean, the statement is clearly cobblers... My thermometer goes much higher [:P]
Even the one inside of my car... Of course these cases don't count.
They are like gigantic ovens if you leave your car in the sun. You can practically warm up your coffee on it (perhaps an idea for Kitchen Science).
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The temperature of lava recorded on at the surface of Kkilauea on Hawaii is 1150 C
(My thermometer does not go thathigh!)
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Did you know there is no proper name for the back of the knees?
(Reg Smeeton)
(in memoriam Vivian Stanshall and John Peel)
Oh yes there is.
Popliteal.
http://en.wikipedia.org/wiki/Popliteal
The next question is why did someone feel the need to invent a word for the back of the knee?
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Did you know "gullible" is not in the dictionary?
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And cleanliness is next to godliness in the same dictionary.
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Did you know that if the sun went out it would take us about 8 seconds to see that it had gone. I'm sure other things would alert us first.
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Did you know that photons never age? (I think!)
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Did you know it's impossible to guarantee that an asynchronous binary input to a synchronous system will always be interpreted as either a "one" or a "zero".
(Think about it the next time you get on a fly-by-wire aircraft.) [:o]
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Did you know there is a species of Japanese bees that defend themselves against intruding wasps by laying on them and vibrating?
This increases the temperature locally to a point that's too much to handle for the wasp, but just not high enough for the bees themselves
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Did you know there is a species of Japanese bees that defend themselves against intruding wasps by laying on them and vibrating?
This increases the temperature locally to a point that's too much to handle for the wasp, but just not high enough for the bees themselves
I think I have seen that. Is it the hornet that invade and try to kill the bees? Im' sure the programme that it was on was showing that the 'natural' bees, had learnt this defence mechanism, but the honey bees who were brought in to help with the orchards did not know how to combat the hornet and were slaughtered.
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Yup that's correct Mrs. H.
Did you know Hebrew (the language) has no numbers?
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It's Mistress H to you Nizzle.. [:P]
Did you know that approx 1.5kg of your body weight made up of bacteria alone.
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Did you know it's impossible to guarantee that an asynchronous binary input to a synchronous system will always be interpreted as either a "one" or a "zero".
(Think about it the next time you get on a fly-by-wire aircraft.) [:o]
Could you explain please?
I find it hard to imagine how the data value could be other than 1 or 0 - albeit wrong - when the ciruitry is bi-state.
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Did you know there is a species of Foxes called Zorros?
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Did you know that zorro is spanish for fox? [:P]
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Did you know Champion the Wonder Horse? [:o)]
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Did you know it's impossible to guarantee that an asynchronous binary input to a synchronous system will always be interpreted as either a "one" or a "zero".
(Think about it the next time you get on a fly-by-wire aircraft.) [:o]
Could you explain please?
I find it hard to imagine how the data value could be other than 1 or 0 - albeit wrong - when the circuitry is bi-state.
"Flip-flops" are indeed bistable. They all rely on positive feedback to operate, so they can also be thought of as rather unstable amplifiers.
In a synchronous system, all the state changes are synchronized, and all signals are have time to propagate and settle at a binary level before the next clock (there can be exceptions to this, but that's the situation the designer would like to achieve.)
So far so good. Now, external events are asynchronous relative to our synchronous system, so an input from the "outside world" can change at any time. There are lots of circuits to synchronize incoming signals, but they all boil down to a method of sampling the incoming asynchronous signal with the clock in the synchronous system and storing the value in a flip-flop.
All is well as long as the asynchronous input does not change during a small time "window" relative to the synchronous clock. In that event, the flip-flop is metastable, in other words, its outputs are indeterminate. Now, typically, because the metastable state (The Grand Old Duke of York had something to do with this btw) is highly unstable because it has a large amount of gain, the flip-flop heads one way or the other rather quickly, so again, all is well.
However, there is a very small time window that can result in the metastable condition lasting rather a long time, which can confuse the "downstream logic".
Still, not to worry. The designer will typically put a second synchronizer behind the first, so that there is a very high probability that the output of the first synchronizer does not violate the "window" of the second synchronizer. However, there is no way to guarantee that the first synchronizer won't violate the window of the second synchronizer.
The second synchronizer does greatly reduce the probability of a "gotcha", and you can always add a third which reduces further still.
In practice, the idea is to make the probability so low that other hard and soft errors (which cannot be eliminated) have a much higher probability of occurrence. All systems are (or should be!) designed to recover from errors, even if it's just a case of hitting the reset button.
So, digital systems may be quite a bit more analogy than we think. And, it's getting worse. The clock speeds of modern chips are so fast, that you have to treat a lot of the internal signals as asynchronous, even though they all derive from the same clock source.
Aaarrrrggg!
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Absolutely, Geezer, and indeed I have seen designs fail because of synchronicity failure. Generally speaking if you add a further synchroniser you can get the failure rate down quite low but, as you say, with high speed systems the chance of failure is higher and with more complex systems there are more things happening so again more chance of failure. It can be hard to convince the uninitiated about this.
Many parts of a digital system can be made fully synchronous but few can be completely so. Interestingly, a very, very major manufacturer of processers used to not to fully appreciate the problems of synchronicity failure (at least in one of their design groups) until it was pointed out to them. I had better not say which company!
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Oh yes! I've been on projects where millions went up in smoke because an engineer relied on the simulation tools too much. They don't always catch these problems. Even worse, because it's a statistical event, the problem only emerges slowly, and only after you've made thousands and thousands of chips and put them in the field. Lab testing is unlikely to surface the problem.
Then you get the phone call in the middle of the night from the chairman of some gigantic corporation wanting to know what you're going to do about it! Sheesh, I'm glad I retired.
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Did you know it's impossible to guarantee that an asynchronous binary input to a synchronous system will always be interpreted as either a "one" or a "zero".
(Think about it the next time you get on a fly-by-wire aircraft.) [:o]
Could you explain please?
I find it hard to imagine how the data value could be other than 1 or 0 - albeit wrong - when the ciruitry is bi-state.
I hate (no I love it) to be pedantic but your later explanation tells us about the possible ways in which the output of a fast and not well synchronised logic circuit element can produce non-logic levels. This is true. Any logic technology, working near its limit, produces analog waveforms and, to reduce errors, synchronous systems were developed in which a clock waveform chooses the most reliable time (in the eye) to determine the logic value. To get the timing right in circuits working at GHz speeds, the lengths of leads need to be correct within a few mm, to reduce timing problems.
BUT you used the word "interpreted" and that implies that somewhere along the line, there was a circuit which "interpreted" the signal (possibly wrongly) and acted upon a logic value - either a 1 or a 0. Strictly, that would be the point at which the signal was interpreted.
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The circuits are all digital. I'm not discussing a case where the clock rate exceeds the speed of the silicon technology employed. In the case of large chips, because the chips are quite large and the clock speeds are so fast, the signals can't always propagate to other areas of the chip to satisfy required setup times. In other words, one clock time is insufficient. This means the signal has to be resynchronized. If it isn't, the receiving stage can go metastable, and create all kinds of problems downstream.
I'm quite confident the processor in your PC has to deal with this situation in many areas of its design.
I don't understand your point re. "interpreted".
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Re "interpreted". I agree with what you say about the analog practicalities of digital circuits; even at speeds well within the operating limits of any logic, the waveforms look nothing like boxcars.
What I mean is that, the analog values in any electronic circuit could be measured with an oscilloscope but that would not be an 'interpretation' of the value. (Timing hazards are also a common problem, which is why synchronous logic needed to be developed.) But, at some point in the system, a decision is made about one of the bits in a decimal digit or the state of a lamp (on / off). I should say that is where the 'interpretation' of the logic value has taken place to produce that state. An 'ideal' signal has been assumed and distortion / noise / hooting and ringing have been interpreted as Errors. Even earlier, in the very first element of combinational logic, an output is produced which cannot be 2/3 or 5/16 - the design and operation of the logic must be based on a hard decision. A OR B cannot produce a Q which is anything other than 1 or 0 or the machine just doesn't work; it's not a functioning binary logic circuit.
Does that distinction make sense to you?
The above doesn't apply to a multi level or soft logic system, of course, but you were referring to a binary syste,m.
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OK. I think I understand.
Well, actually it is a case where A (some operation) B = Z!
You can actually set up an experiment to observe it.
Take a common or garden D flip-flop. 74XX74 for example
Hook it's D input to one clock source and it's Clock input to another source. One of the clocks needs to be adjustable. Put scope probes on D, C and Q. Trigger on C.
Now adjust the clock so that it beats very slowly with the other clock.
Occasionally you will observe a faint trace where the Q output "hangs around" at a level that neither represents one or zero for an interval that is much greater than the propagation delay through the flip-flop. That's the metastable condition. It's neither up nor down! Empirically, faster technologies display shorter metastable intervals, but you really don't know how long they could last.
The chip manufacturers only guarantee the behavior of a device if you satisfy the setup and hold times for the inputs. If you violate them, they make no claims about what will happen and how long the metastable condition will last.
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Did you know it's not nice to hijack topics?
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Did you know Albert Einstein was an excellent violinist?
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I know that Albert could play the violin better than Sherlock Holmes. Dunno about "excellent".
I also reckon that he would have been interested in logic states within circuits.
This (you refer to hijacking) is always a risk with a thread which tries to be a forum in forum. Perhaps we should have a breakout after three posts rule? But wouldn't that be a Just Chat thread?
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I know that Albert could play the violin better than Sherlock Holmes. Dunno about "excellent".
He was, in all case, a better violinist than I was. [:)]
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"Was"?
Are you improving then?
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No. Mine was a rent. Couldn't afford to buy it at that time.
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Did you know it's not nice to hijack topics?
Did you know that STB is preferable to just hijacking?? [;D]
http://www.thenakedscientists.com/forum/index.php?topic=19703.0 (http://www.thenakedscientists.com/forum/index.php?topic=19703.0)
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What has a Set Top Box got to do with this thread?
I've been out-acronymed.
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Did you know it's not nice to hijack topics?
Quite right! We should have started a new thread. [B)]
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Support Training Battalion ???
Give us a clue.
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Support Training Battalion ???
Give us a clue.
Errrr the clue was in the link posted along with my comment SC!
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Did you know NSF stands for Naked Science Forum AND National Science Foundation?
(I think they should change their name to avoid confusuion)
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Did you know NSF stands for Naked Science Forum AND National Science Foundation?
(I think they should change their name to avoid confusuion)
It also stands for Naughty Sexy Frillies...
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or Nutty Scientists Federation
But to be a good scientist you have to think in a nutty way sometimes.
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Did you know that a human has approximately the same number of hair follicles as most other apes?
(At least they do to start with. If you are going bald, that's a different story.)
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Did you know around 43% of the world bicycles are in China?
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It also stands for Naughty Sexy Frillies...
I wouldn't have expected this from somebody else.
Did you know there are only 40 Amur leopards left in the world?
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Did you know that cowboys don't wear those fringy leather strips hanging off the sleeves and backs of their jackets as a fashion statement and that they are actually there to wick moisture away when they get wet?
Least, that's what they told me, and I was not about to argue.
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....that if a hydrogen atom was the size of football field, its proton would be the size of an ant?
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Did you know 13% of people are left-handed?
In medieval times, left-handed people could not become knights because it was thought that they were descendants of the devil, it is said. Spiral staircases in castles ran clockwise to allow knights – all right-handed – to battle intruders effectively.
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Did you know 13% of people are left-handed?
In medieval times, left-handed people could not become knights because it was thought that they were descendants of the devil, it is said. Spiral staircases in castles ran clockwise to allow knights – all right-handed – to battle intruders effectively.
Is the same reason to ride on the left hand side of the path, in order to battle effectively.
This was not applied to jousting.