Featured Title:
See Your Book Here |
 |
| The Ancient Celts, Barry Cunliffe |
 |
| Login |
|
Don't have an account yet? You can create one. As a registered user you have some advantages like your own home page, fewer ads, and your contributions link to your page. |
| Who's Online |
There are currently, 97 guests and 0 members online.
You are a guest. To join in, please register for free by clicking here |
| |
| Review your Reply |
Klingon
Joined:
08-08-2004
Messages: 758
from Germany
 OFF-Line
|  New Message Posted!2011-11-21 08:10
Quote:
| On 2011-11-18 22:00, davidmorgan wrote:
Wow, how big is a trillionth of a degree? I see that Google maps appears to show UK sites to 12 decimal places! |
|
Converting coordinates from British National Grid to longitude/latitude always resulting in numbers with many decimal places. It doesn't make sense to use them. Only if you want convert long/lat back to BNG it's good to have these otherwise the result is inaccurate.
|
frogcottage42
Joined:
14-02-2010
Messages: 235
from tuosist
OFF-Line
|  New Message Posted!2011-11-20 15:28
yeah, I think that just about covers it!
It's all about us attaching values and quantities to things which don't always suit these constrictions.
As for wandering outside of the scope of the thread I would have to offer undefined quantative restrictions as an excuse. I guess it's a question of degree?
|
davidmorgan
Joined:
23-11-2006
Messages: 1620
from The New Forest
OFF-Line
| New Message Posted!2011-11-19 19:16
Sure, it does depend on where you are, frogcottage. But going beyond that (it being sort of equal at the equator - ignoring the oblateness of the earth) then, with the knowledge that the latitude lines have a constant separation, one is really dealing with the only variable in this equation, i.e. longitude.
So, the range of the length of a degree (after all we're dealing with Google map's earthbound UK coordinates - based on the conversion of Ordnance Survey grid refs?) goes from x at the equator to zero at the poles.
I think Drew is out by quite a large factor. Take Stonehenge as an example at about 50 degrees north - according to this calculator, 1 degree is about 71696 metres, divided by 1,000,000,000,000 = 0.000000071696 metres.
I'm not a scientist but I'm guessing we're practically down to the molecular/atomic level with such a number. (Just looked it up - 1 ångström is 1 ten-billionth of a metre - "under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 angstroms" - so we're talking about something like 240 atoms' width here?)
For me this just reinforces my opinion that computer people often have no common sense, and reminds me of the time when I used to design banking systems and (obviously giving a little too much leeway to the programmers) had to point out to someone that he never received a bank statement with 3 decimal places, and also of that ridiculous recent episode with Lloyds bank's download statement option on internet banking which reversed the debit and credit columns and also reversed the date order of the transactions (still does the date order wrong - idiots!).
However, an apologist for those Google guys might say that this is a general equation applied to the limitations of the earth as a subset of the universe and therefore does apply. I guess that's what "if applied to the universe in general surely it is from zero at point of origin to infinity" is about. But surely meaningless when pinpointing sites on the surface of this planet?
No, you're not missing anything earlier in the thread, frogcottage, just wandering a little outside the scope of the brief, that's all.
|
frogcottage42
Joined:
14-02-2010
Messages: 235
from tuosist
OFF-Line
| New Message Posted!2011-11-19 14:45
surely it depends on where you are? the latitude may remain constant but the longitude goes from max at equator to zero at the poles? or did I miss an earlier part of this thread?
and if applied to the universe in general surely it is from zero at point of origin to infinity?
|
DrewParsons
Joined:
10-06-2008
Messages: 215
from New Zealand
OFF-Line
| New Message Posted!2011-11-18 22:57
I think it is 0.000111 metres (approximately!!!)
|
davidmorgan
Joined:
23-11-2006
Messages: 1620
from The New Forest
OFF-Line
| New Message Posted!2011-11-18 22:00
Wow, how big is a trillionth of a degree? I see that Google maps appears to show UK sites to 12 decimal places!
| |
|
Main News