Seeker
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On 6/5/2018 at 3:34 PM, mererdog said:
Sure. But by basing the meter on a physical object, you have an objective, verifiable standard. You can hold things up to the stick and ask "How do these things compare?" Basing the the meter on its relationship to c means you can do no direct comparison. Instead, you have to build on a pile of inferences.
"This is true, so I infer that must be true. Since I infer that is true, I also infer the other is true. Therefore, I conclude that this physical object I am attempting to measure compares to c in this way."
Any bad inference in the chain destroys the accuracy of the conclusion. The more complex the chain, the easier it is for bad inferences to hide. And the more people who make the same bad inference, the harder it is for anyone to notice it is a bad inference.
A dozen people using the same warped meter stick to measure something a dozen times does not provide a more accurate measurement than one guy using a straight meter stick once. But if you cant tell the stick is bent, it will look accurate.
The new standard is objective and verifiable.
You seem to be deliberately ignoring what I said. "Your stick is good enough for all practical purposes." You don't need an atomic clock to boil an egg, and I am not suggesting you record your mileage in fractions of a light-second.
However, when you and a friend both have metre sticks, which each of you think are accurate, but are of slightly different lengths, what then? The normal solution is to have a reference stick which is manufactured to higher tolerances, and it used to calibrate the everyday measures. You then have the same problem again if two of those reference measures disagree, and so on up the chain. The 19th century method which you seem to be advocating is to have a single physical object to which all the high-level references are compared. Unfortunately, physical objects vary with temperature, humidity, corrosion, wear-and-tear, etc. The modern approach is to tie the standards directly to fundamental elements of the Universe.
Please note that there is none of your implied drift off into intellectual la-la land here. The comparisons are tricky, sure, but the derivation is measurement-by-measurement, not just inference-by-inference.
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4 hours ago, mererdog said:
Ok. I have a meter stick. I can point to it and say "That is a meter." When you use meters in your measurements, that is ,essentially, my basis for comparison. This is how I, and the majority of the world, define a meter. Change the length of a meter and you have to change everyone's speedometerss, you know?
Yes. Your stick is good enough for all practical purposes. However for many scientific purposes it is necessary to be ridiculously precise, and so the scientific "stick" is chosen in a way which makes it consistent in as many circumstances as possible. If you raise or lower the temperature for example, your stick will be slightly longer or shorter, whereas a light-second and hence a scientific metre will remain constant.
As to changing the speedos, remember I said 0.02 parts per billion? That's the equivalent of measuring the entire width of the continental US and being out by less that the width of a hair. The length of the SI metre been more accurately defined, but lies within the limits of accuracy of previous standards. No adjustment necessary.
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4 hours ago, mererdog said:
From the wiki link you provided- "Consequently, accurate measurements of the speed of light yield an accurate realization of the metre rather than an accurate value of c."
Lets say I define a meter as the distance from my head to my feet. I measure the distance from my head to my feet and come up with 3 inches. So a meter is now defined by me as 3 inches. Does this mean my measurement is accurate, by definition? No.
Lets say I define a dog as a horse. A horse is still a horse and a dog.is still a dog. The only thing that changes is how well I can communicate about dogs and horses with others.
so, pretend we discover that light actually travels twice as fast as currently measured. So, by definition, a meter is two meter sticks long. This means only half a liter fits in a one liter jug. It means, in other words, that not everyone is using the same basis of comparison in their measurements, creating a situation with competing definitions and a lack of mutual understanding.
But that presupposes that "dog" and "horse" have fixed referents. If everyone called the riding animal a dog and the domestic pet a horse there would be no communication difficulty.
Units of measurement need a defined reference or they are meaningless. The metre was originally defined as 1/10,000 of the distance between the Equator and the North Pole measuring along the meridian which passed through Paris. That's a little difficult to use when you are measuring cloth, so a measuring stick was created which was as close as they could make it to the desired length, and then copies were made (to varying degrees of accuracy) and distributed, and copied, and distributed, and used for practical measurements. It doesn't matter whether you call it a metre or a sticklength or a horse, the important thing is the underlying unit.
In the case of the speed of light, we have a physical constant (c), measured in units of distance over time. Representatives of the scientific community got together (hence bypassing your linguistic quibble) and decided that rather than defining c in terms of the metre and the second, they would instead define the the metre in terms of c and the second. The relationship between the 3 remains the same in the real world, but it means that the length of the metre is now fixed unless either c or the definition of the second changes. If the real-world value of c were discovered to have changed, then the length of the si metre would by definition change. It's like inflation. If the value of the dollar falls, the value of the cent falls with it. Unlike inflation, though, we're pretty sure that c is a constant.
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On 6/1/2018 at 9:14 PM, cuchulain said:
how did scientists determine the factual speed of light? what subjective evidence led to a concrete and factual, non subjective number?
There is some good info in the measurement section of the Wikipedia speed of light article.
The metre is now defined relative to the speed of light, so the speed of light in m/s is now 100% accurate by definition. The value of the second has a separate source, so it is still meaningful to ask how accurate the measurements are. Prior to adopting the current definitions, the accuracy was around 0.02 parts per billion.
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So this wag wants to know which tailIban?
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On 10/11/2017 at 4:25 AM, Jonathan H. B. Lobl said:
Some scientists have a great sense of humor. My favorite physics term is W.I.M.P.
Weak
Interactive
Massive
Particle.
Same basic idea, but I thought it was "weakly interacting massive particle". They contrast with MACHOs (massive astrophysical compact halo objects) as rival explanations for dark matter.
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In terms of atmospherics the two overlap, so it is not generally possible to definitively tell the two apart from a photo of an unknown location.
However... activity during the day (both natural and human) tends to produce a lot of dust, so sunsets are typically redder but more hazy, whereas sunrises are usually clearer and brighter. That means you can often make a good guess as to which is which.
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I've never even seen them for sale. Do you know of any which are available online?
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Welcome ScorpioMystic.
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And here I thought you had misspelled Rabbit and were a follower of Elil-hrair-rah.
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On 24/02/2018 at 1:55 PM, mererdog said:
I think that not having your needs met is the only way to learn how to reach the top of the pyramid amd attain "self actualization." We need at least a little deprivation to build empathy and motivation. Struggle keeps us strong.
That's why I said not all the wants. If you don't have your needs (at least at tier 1) you are dead. That doesn't make you strong.
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I think the hierarchy of needs is worth reviewing here (https://en.wikipedia.org/wiki/Maslow's_hierarchy_of_needs).
A lot of the arguments above seem to stem from category errors when desiderata from different levels of the hierarchy are compared. It seems to me that the Good Life TM involves having all of your needs (but probably not all of your wants) at all levels met.
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I find it useless to debate free will in the context of a moral argument. If we do not have free will (ie we cannot make a meaningful choice), then there is no moral action - what we do is inevitable.
It may be a point of interest in other contexts, but in a moral debate, free will is a necessary assumption.
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Argument, circular: See circular argument.
Circular argument: See argument, circular.
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Against a clear sky
the dancing branches proudly bear
One frost-withered bud.-
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I see that too. As soon as I move elsewhere, it's OK - I am still actually logged in..
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A label I sometimes use is "militant agnostic". The key statement would be "I don't know, and you sure as ** don't know either".
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One candle burns out
Many others lit from it
Continue to shine,
Goodbye Atwater, blessed be.
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Nice poems Joyful, thanks for posting them.
The haiku form is quite closely tied to Japanese, so it is hard to draw a clear line in western works, but I would not consider either of those to be haiku.
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13 hours ago, Jonathan H. B. Lobl said:
The person who hires the band, gets to pick the music.
But the band may not necessarily be able or willing to play it.
Ain't analogies fun?
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I, too, prefer to just go by my given name.
When people insist on calling me Mr X, I then will usually say it should be Rev. X, but I prefer you just to use my name. Organization types seem to freak out a bit at that for some reason.
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I quite liked the term "differently abled", but since I'm mundanely abled, I don't think it's any of my business to choose.
Again. it's almost certainly well meant, but renaming a group of people to "protect" them seems awfully patronizing to me.
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OK, thanks for the quick response.
I'll see how things develop.
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Apple 8, X....new watch
in Science, Technology & Innovation
Posted
If you are planning on building from anyone else's code, make sure you get the full source code including any libraries, and check what information it is collecting and transmitting about your users.