Forum Home Forum Home > Topics not related to music > General discussions
  New Posts New Posts RSS Feed - The UFO Phenomenon
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Topic ClosedThe UFO Phenomenon
 Post Reply Post Reply Page  <1 34567 26>
Author
Message
  Topic Search Topic Search  Topic Options Topic Options
The Dark Elf View Drop Down
Forum Senior Member
Forum Senior Member
Avatar
VIP Member

Joined: February 01 2011
Location: Michigan
Status: Offline
Points: 13109 		Direct Link To This Post Posted: April 23 2013 at 22:17
Originally posted by Dean Dean wrote:

P = I(ave)*4*PI()*r^2 ... where r is 4.2 lightyears in metres and I(ave) is the CMBR average power intensity


Perhaps it would be easier if you just read us "Horton hears a Who", Dean. Same message, but simpler for the mathematically disinclined.  LOL


Edited by The Dark Elf - April 23 2013 at 22:19
...a vigorous circular motion hitherto unknown to the people of this area, but destined
to take the place of the mud shark in your mythology...
Back to Top
Padraic View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: February 16 2006
Location: Pennsylvania
Status: Offline
Points: 31169 		Direct Link To This Post Posted: April 23 2013 at 22:19
Sorry.  Normally this is the sort of thing Dean and I could work out at the pub, but there's a big pesky ocean in the way.
Back to Top
Dean View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin and Amateur Layabout

Joined: May 13 2007
Location: Europe
Status: Offline
Points: 37575 		Direct Link To This Post Posted: April 24 2013 at 01:32
Originally posted by Padraic Padraic wrote:

Sorry.  Normally this is the sort of thing Dean and I could work out at the pub, but there's a big pesky ocean in the way.
To the inevitable dismay of our respective partners and anyone else drinking with us, this would be true.
 
We'd propbably work out how long the journey would take at Warp 8 and when Voyager 1 will get there for good measure.
 
Anyway, just done a quick dimensional analysis check on the formula I used and the value I calculated has units of J/s, which is power. Can't see an error in the magnitudes of the numbers either so I'm sticking to 240 zettawatts, a high-gain antenna would reduce that to 2.4etawatts if the power didn't vapourise it at switch-on.
What?
Back to Top
Jim Garten View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin & Razor Guru

Joined: February 02 2004
Location: South England
Status: Offline
Points: 14693 		Direct Link To This Post Posted: April 24 2013 at 02:25
Originally posted by Dean <strong><u>Today at 06:32</strong></u> Dean Today at 06:32 wrote:

Anyway, just done a quick dimensional analysis check


Dean - for gods' sake - at that time of the morning, I was trying to work out which way was up! Do you have some kind of external brain-drive to store extra capacity?

I think by comparison, mine is akin to my first PC - a 286 with a 20mb hard drive

Jon Lord 1941 - 2012
Back to Top
Dean View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin and Amateur Layabout

Joined: May 13 2007
Location: Europe
Status: Offline
Points: 37575 		Direct Link To This Post Posted: April 24 2013 at 02:34
^ Jim forgot to put the clocks forward LOL
 
Welcome to BST Jim.
What?
Back to Top
Jim Garten View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin & Razor Guru

Joined: February 02 2004
Location: South England
Status: Offline
Points: 14693 		Direct Link To This Post Posted: April 24 2013 at 02:43
Git!

[edit]

Anyway - even at 07:32, I'd (probably) worked out which way was up & was then working on the multitasking conundrum that is first coffee & cigarette of the day!

That's as far as I get of a morning.



have I called you a git, yet?

Edited by Jim Garten - April 24 2013 at 02:45

Jon Lord 1941 - 2012
Back to Top
Dean View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin and Amateur Layabout

Joined: May 13 2007
Location: Europe
Status: Offline
Points: 37575 		Direct Link To This Post Posted: April 24 2013 at 03:05
Originally posted by Jim Garten Jim Garten wrote:


have I called you a git, yet?
More than once. LOL
What?
Back to Top
The Doctor View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: June 23 2005
Location: The Tardis
Status: Offline
Points: 8543 		Direct Link To This Post Posted: April 24 2013 at 07:55
Originally posted by Jim Garten Jim Garten wrote:

Git!

[edit]

Anyway - even at 07:32, I'd (probably) worked out which way was up & was then working on the multitasking conundrum that is first coffee & cigarette of the day!

That's as far as I get of a morning.



This + I'm still trying to convince myself that it wouldn't just be better for all concerned if I called it a day and went back to bed. 
I can understand your anger at me, but what did the horse I rode in on ever do to you?
Back to Top
Padraic View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: February 16 2006
Location: Pennsylvania
Status: Offline
Points: 31169 		Direct Link To This Post Posted: April 24 2013 at 09:36
Originally posted by Dean Dean wrote:

Originally posted by Padraic Padraic wrote:

Sorry.  Normally this is the sort of thing Dean and I could work out at the pub, but there's a big pesky ocean in the way.
To the inevitable dismay of our respective partners and anyone else drinking with us, this would be true.
 
We'd propbably work out how long the journey would take at Warp 8 and when Voyager 1 will get there for good measure.
 
Anyway, just done a quick dimensional analysis check on the formula I used and the value I calculated has units of J/s, which is power. Can't see an error in the magnitudes of the numbers either so I'm sticking to 240 zettawatts, a high-gain antenna would reduce that to 2.4etawatts if the power didn't vapourise it at switch-on.

Units are indeed correct, but the magnitude implies that if I have a 1 m2 antenna I would be receiving a power of -19.2 dBm from the CMBR, which can't be true.
Back to Top
The Doctor View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: June 23 2005
Location: The Tardis
Status: Offline
Points: 8543 		Direct Link To This Post Posted: April 24 2013 at 09:38
My brain just melted. 
I can understand your anger at me, but what did the horse I rode in on ever do to you?
Back to Top
Jim Garten View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin & Razor Guru

Joined: February 02 2004
Location: South England
Status: Offline
Points: 14693 		Direct Link To This Post Posted: April 24 2013 at 09:49
Don't worry about it Chester

Quote I have a 1 m2 antenna I would be receiving a power of -19.2 dBm from the CMBR


They're just putting together random collections of numbers & letters now.

Personally I thought it was self evident that a +/- ratio of Pi to the power of x/y (where y is a constant N factor, of course) would result if an amplitude gain sufficient to reach Proxima Centuri.

See?

Jon Lord 1941 - 2012
Back to Top
The Doctor View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: June 23 2005
Location: The Tardis
Status: Offline
Points: 8543 		Direct Link To This Post Posted: April 24 2013 at 09:56
^LOL I should've known.  -19.2 dBm. CMBR.  Pah! It doesn't even sound like real stuff, now that my morning fog is starting to lift finally.
I can understand your anger at me, but what did the horse I rode in on ever do to you?
Back to Top
Padraic View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: February 16 2006
Location: Pennsylvania
Status: Offline
Points: 31169 		Direct Link To This Post Posted: April 24 2013 at 10:01
VOGON CAPTAIN:
There's no point in acting all surprised about it. All the planning charts and demolition orders have been on display at your local planning department in Alpha Centauri for fifty of your Earth years so you've had plenty of time to lodge any formal complaints and its far too late to start making a fuss about it now. 

MANKIND:
[Louder yells of protest] 

VOGON CAPTAIN:
What do you mean you've never been to Alpha Centauri? Oh for heaven sake mankind it's only four light years away you know! I'm sorry but if you can't be bothered to take an interest in local affairs that's your own regard. Energise the demolition beams! God I don't know…apathetic bloody planet, I've no sympathy at all… 

Tongue
Back to Top
Dean View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin and Amateur Layabout

Joined: May 13 2007
Location: Europe
Status: Offline
Points: 37575 		Direct Link To This Post Posted: April 24 2013 at 10:07
Originally posted by Padraic Padraic wrote:


Units are indeed correct, but the magnitude implies that if I have a 1 m2 antenna I would be receiving a power of -19.2 dBm from the CMBR, which can't be true.
 
Originally posted by Padraic Padraic wrote:

That number seems high. Please show your work. Wink
 
What?
Back to Top
Padraic View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: February 16 2006
Location: Pennsylvania
Status: Offline
Points: 31169 		Direct Link To This Post Posted: April 24 2013 at 10:09
10*log10(40e-15 * 3e8) + 30
Back to Top
Padraic View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: February 16 2006
Location: Pennsylvania
Status: Offline
Points: 31169 		Direct Link To This Post Posted: April 24 2013 at 10:11
Here, try plugging some numbers into this and see if your zettawatt number makes sense.
Back to Top
Dean View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin and Amateur Layabout

Joined: May 13 2007
Location: Europe
Status: Offline
Points: 37575 		Direct Link To This Post Posted: April 24 2013 at 10:39
Originally posted by Padraic Padraic wrote:

Here, try plugging some numbers into this and see if your zettawatt number makes sense.
 
 
Okay did that - arrived at -136dBW, which equates to 21.7fW
 
That would look like snow on my old Sony TV
What?
Back to Top
Padraic View Drop Down
Special Collaborator
Special Collaborator
Avatar
Honorary Collaborator

Joined: February 16 2006
Location: Pennsylvania
Status: Offline
Points: 31169 		Direct Link To This Post Posted: April 24 2013 at 10:49
OK, so thermal noise at 300 K is -204 dBW/Hz.  I'll give you 1 kHz of bandwidth for transmission, so that gives us -174 dBW noise floor.  So you have an SNR of 40 dB, a pretty whopping signal.

I'm not saying you don't need a shedload of power - you most obviously do, we're probably quibbling over a few orders of magnitude of power levels that exceed that what the entire planet consumes.

Bottom line is we agree on the broader point that thanks to all this geekery I've now forgotten.
Back to Top
Dean View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin and Amateur Layabout

Joined: May 13 2007
Location: Europe
Status: Offline
Points: 37575 		Direct Link To This Post Posted: April 24 2013 at 11:16
Originally posted by Padraic Padraic wrote:

OK, so thermal noise at 300 K is -204 dBW/Hz.  I'll give you 1 kHz of bandwidth for transmission, so that gives us -174 dBW noise floor.  So you have an SNR of 40 dB, a pretty whopping signal.
Well, no - the SNR is zero - I suspect we're now at cross-purposes.
Originally posted by Padraic Padraic wrote:

I'm not saying you don't need a shedload of power - you most obviously do, we're probably quibbling over a few orders of magnitude of power levels that exceed that what the entire planet consumes.
Aye, and consumption levels are several magnitudes higher than what leaks out into space.
Originally posted by Padraic Padraic wrote:

Bottom line is we agree on the broader point that thanks to all this geekery I've now forgotten.
Aye.
 
Originally posted by Dean Dean wrote:

Please explain how our presence on this planet would be easily detectable - please feel free to be as technical as you like, it's been 30 years since I studied telecommunications at University but I'm sure it will all come back to me.
... apparently not as quickly as I would have hoped. LOL
What?
Back to Top
Jim Garten View Drop Down
Special Collaborator
Special Collaborator
Avatar
Retired Admin & Razor Guru

Joined: February 02 2004
Location: South England
Status: Offline
Points: 14693 		Direct Link To This Post Posted: April 24 2013 at 11:27
Which is as good a time as any for a break & a word from our sponsors



...and we're back

Edited by Jim Garten - April 24 2013 at 11:28

Jon Lord 1941 - 2012
Back to Top
 Post Reply Post Reply Page  <1 34567 26>

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.199 seconds.
Donate monthly and keep PA fast-loading and ad-free forever.