Re: [time-nuts] Time of death-Again
These pulsars have different rates. Could one use the relative timing of
two or three pulsars? that is, T=0 is when pulsar A, B, and C are
coincident. (or is the "beat rate" between them too high to be useful)
That's an interesting idea... Thanks.
Let's ignore the problem of communicating the agorithm to non-English
speakers.
I think there are two problem areas. Basically, the data isn't integer. One
fuzzy area is the period. The other is measuring an individual pulse.
Suppose you have 2 pulsars that might line up several or many years ago.
What does that mean? Suppose you know the periods to N decimal places. What
does "line up" mean? How close do they have to be?
Suppose you only have to go back a few years until things line up. Then the
major problem is the uncertainty on an individual pulse.
Suppose you have to go back a zillion years. Now the fuzz on the period adds
to the fuzz on measuring an individual pulse.
Mumble. I'm probably in way over my head at this point.
--
These are my opinions, not necessarily my employer's. I hate spam.
At least with this method at any time you can always work out when t=0
is. With other events (eg supernova) you can't.
On Saturday, October 30, 2010, Hal Murray hmurray@megapathdsl.net wrote:
These pulsars have different rates. Could one use the relative timing of
two or three pulsars? that is, T=0 is when pulsar A, B, and C are
coincident. (or is the "beat rate" between them too high to be useful)
That's an interesting idea... Thanks.
Let's ignore the problem of communicating the agorithm to non-English
speakers.
I think there are two problem areas. Basically, the data isn't integer. One
fuzzy area is the period. The other is measuring an individual pulse.
Suppose you have 2 pulsars that might line up several or many years ago.
What does that mean? Suppose you know the periods to N decimal places. What
does "line up" mean? How close do they have to be?
Suppose you only have to go back a few years until things line up. Then the
major problem is the uncertainty on an individual pulse.
Suppose you have to go back a zillion years. Now the fuzz on the period adds
to the fuzz on measuring an individual pulse.
Mumble. I'm probably in way over my head at this point.
--
These are my opinions, not necessarily my employer's. I hate spam.
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El 30/10/2010 10:31, Hal Murray escribió:
Suppose you have to go back a zillion years. Now the fuzz on the period adds
to the fuzz on measuring an individual pulse.
Not to forget that pulsar frequencies spins down as the energy that they
emits is ultimately drawn from its rotational energy (PSR B1937+21 spins
down at 1.05 x 10^-19 seconds per second). In a zillion years this could
amount a bit of time (several hundred microseconds over the 2.29 x 10e8
years life of this pulsar if the spin down rate would have been constant
- too much drift for a real time-nut ;) )
Regards,
Javier
--
Javier Herrero EMAIL: jherrero@hvsistemas.com
Chief Technology Officer
HV Sistemas S.L. PHONE: +34 949 336 806
Los Charcones, 17 FAX: +34 949 336 792
19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com
If you use n pulsars of different frequencies where n is a large
number, then individual pulsars
could do dramatic things and the rest would still define your time.
Include their spin down rate, velocity and position and I think that you
could define a time scale that would enable elapsed time to be deduced
from any arbitrary zero from the phases of all the pulsars.
It is a little like a random version of the method they use for distance
measurement with lasers where they modulate the beam with
IKHz, 10KHz, 100KHz, 1MHz, 10MHz etc and by observing the
phase of each they work out the time delay of flight.
cheers, Neville Michie
On 30/10/2010, at 9:31 PM, Javier Herrero wrote:
El 30/10/2010 10:31, Hal Murray escribió:
Suppose you have to go back a zillion years. Now the fuzz on the
period adds
to the fuzz on measuring an individual pulse.
Not to forget that pulsar frequencies spins down as the energy that
they emits is ultimately drawn from its rotational energy (PSR B1937
+21 spins down at 1.05 x 10^-19 seconds per second). In a zillion
years this could amount a bit of time (several hundred microseconds
over the 2.29 x 10e8 years life of this pulsar if the spin down
rate would have been constant - too much drift for a real time-
nut ;) )
Regards,
Javier
--
On Oct 30, 2010, at 3:31 AM, Javier Herrero jherrero@hvsistemas.es wrote:
El 30/10/2010 10:31, Hal Murray escribió:
Suppose you have to go back a zillion years. Now the fuzz on the period adds
to the fuzz on measuring an individual pulse.
Not to forget that pulsar frequencies spins down as the energy that they emits is ultimately drawn from its rotational energy (PSR B1937+21 spins down at 1.05 x 10^-19 seconds per second). In a zillion years this could amount a bit of time (several hundred microseconds over the 2.29 x 10e8 years life of this pulsar if the spin down rate would have been constant - too much drift for a real time-nut ;) )
But if the decay rate is known, you could factor that into your calculation. In fact wouldn't specifying the time of an event as the observed phase of the pulsars be unique. That is if something is at a time of 75%A,22%B,54%C, does that specify a unique time and place?
Percent, here, is where the event occurred in the period between the pulses
On Oct 30, 2010, at 4:33 AM, Neville Michie namichie@gmail.com wrote:
If you use n pulsars of different frequencies where n is a large number, then individual pulsars
could do dramatic things and the rest would still define your time.
Include their spin down rate, velocity and position and I think that you
could define a time scale that would enable elapsed time to be deduced
from any arbitrary zero from the phases of all the pulsars.
It is a little like a random version of the method they use for distance
measurement with lasers where they modulate the beam with
IKHz, 10KHz, 100KHz, 1MHz, 10MHz etc and by observing the
phase of each they work out the time delay of flight.
cheers, Neville Michie
Or how GPS works
On 10/30/2010 04:48 PM, Jim Lux wrote:
On Oct 30, 2010, at 3:31 AM, Javier Herrerojherrero@hvsistemas.es wrote:
El 30/10/2010 10:31, Hal Murray escribió:
Suppose you have to go back a zillion years. Now the fuzz on the period adds
to the fuzz on measuring an individual pulse.
Not to forget that pulsar frequencies spins down as the energy that they emits is ultimately drawn from its rotational energy (PSR B1937+21 spins down at 1.05 x 10^-19 seconds per second). In a zillion years this could amount a bit of time (several hundred microseconds over the 2.29 x 10e8 years life of this pulsar if the spin down rate would have been constant - too much drift for a real time-nut ;) )
But if the decay rate is known, you could factor that into your calculation. In fact wouldn't specifying the time of an event as the observed phase of the pulsars be unique. That is if something is at a time of 75%A,22%B,54%C, does that specify a unique time and place?
If you would have constant rates and three phase observables that would
give you a unique time modulus the beating period of this oscillator
combination. To solve it you would use the chinese reminder. However,
the chinese reminder theorem does not handle case with changing rates.
Also, the ability to predict deep into the futures is severely limited
by the precision of our modelling of these sources and possible other
effects playing in on them. Also, the precision by which we makes the
measures is a limiting factor. Sorting all of this out would
Percent, here, is where the event occurred in the period between the pulses
Degrees would have helped more.
I think pulsars alone would be difficult for long-term, omni-positional
timing. We haven't even touched on stellar movements over long time periods.
Also, our observation will be in movement from the various sources, so
doppler compensation would be required.
It's not a completely unsolveable thing, but a lot of things shifting
over time throwing in massive of unknown parameters which would need to
be estimated with sufficient precision if we where to build from scratch
the time and time-scale.
Just agreeing on the definitions of the star-book to traverse cultural,
time and position boundaries would be an interesting problem.
Cheers,
Magnus
On Oct 30, 2010, at 6:31 AM, Javier Herrero wrote:
El 30/10/2010 10:31, Hal Murray escribió:
Suppose you have to go back a zillion years. Now the fuzz on the period adds
to the fuzz on measuring an individual pulse.
Not to forget that pulsar frequencies spins down as the energy that they emits is ultimately drawn from its rotational energy (PSR B1937+21 spins down at 1.05 x 10^-19 seconds per second). In a zillion years this could amount a bit of time (several hundred microseconds over the 2.29 x 10e8 years life of this pulsar if the spin down rate would have been constant - too much drift for a real time-nut ;) )
I was assuming that the spin periods of the pulsars was the actual clock in question for the million year time scale. If the knowledge of
our date system is lost it is highly probably that the pulsar phase will also be lost, so there is no chance of doing sub-second timing, but from the spin period of epoch it should be possible to date the elapsed time to order a year, even over a million years.
If you then included information the orbital state of the planets at a specified data in this epoch the finders might be able to use the pulsars to figure out the elapsed time to within a few years and then use the planet data to figure out what the elapsed time is to better than a day and thus get the actual date. (Planetary alignments tend to repeat, so you need some source of absolute time to do this.) I have no ideas short of burying a working clock on doing any better than that. (The change in the UT1 approaches a day even over historic time, and will be many days in a million years, so you will really be getting ET / TAI not UTC out of this.)
Regards
Marshall
Regards,
Javier
--
Javier Herrero EMAIL: jherrero@hvsistemas.com
Chief Technology Officer
HV Sistemas S.L. PHONE: +34 949 336 806
Los Charcones, 17 FAX: +34 949 336 792
19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com
time-nuts mailing list -- time-nuts@febo.com
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It appears that there is no way of placing an event in time
across a cultural discontinuity (aliens, bombed back into the
stone age). Referencing an event in the past by an event in
the sky is no good if the new culture has no record of that
event.
For pulsar phases and radioactive decay, things get fuzzy
quickly as you try to extrapolate back in time from present
behavior. Also, the old culture had to have had the technology
to make the phase or decay measurements, but we're talking
about our own culture as it is today.
Dating with Carbon 14 is not certain, even if the laws of
atomic decay don't change (and we're talking about a time
before proton decay becomes prevalent). C14 is assumed to be
created at a constant rate by gamma rays in the upper atmosphere.
When a living thing dies, it always has the same ratio of C14
to C12 because C14 is assumed to be distributed uniformly through
the atmosphere. After death, the amount of C14 decays with a half
life of about 6000 years. This is adequate for human history, but
not on a cosmological scale.
See http://en.wikipedia.org/wiki/Radiocarbon_dating for the full
story. The rate of C14 formation depends on the strength of the
Earth's magnetic field as it affects gamma rays. The amount of
atmospheric C14 doubled during atomic testing. The distribution
of C14 in the atmosphere is not uniform. And so on.
Too bad. I was thinking that isotope dating could get you in the
neighborhood, where you could fine tune the estimate with pulsar
phase relationships -- if you could locate the pulsars and
predict their behavior at that time.
Bill Hawkins
-----Original Message-----
From: Magnus Danielson
Sent: Saturday, October 30, 2010 10:42 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Time of death-Again
On 10/30/2010 04:48 PM, Jim Lux wrote:
On Oct 30, 2010, at 3:31 AM, Javier Herrerojherrero@hvsistemas.es
wrote:
El 30/10/2010 10:31, Hal Murray escribió:
Suppose you have to go back a zillion years. Now the fuzz on the period
adds
to the fuzz on measuring an individual pulse.
Not to forget that pulsar frequencies spins down as the energy that they
emits is ultimately drawn from its rotational energy (PSR B1937+21 spins
down at 1.05 x 10^-19 seconds per second). In a zillion years this could
amount a bit of time (several hundred microseconds over the 2.29 x 10e8
years life of this pulsar if the spin down rate would have been constant -
too much drift for a real time-nut ;) )
But if the decay rate is known, you could factor that into your
calculation. In fact wouldn't specifying the time of an event as the
observed phase of the pulsars be unique. That is if something is at a time
of 75%A,22%B,54%C, does that specify a unique time and place?
If you would have constant rates and three phase observables that would
give you a unique time modulus the beating period of this oscillator
combination. To solve it you would use the chinese reminder. However,
the chinese reminder theorem does not handle case with changing rates.
Also, the ability to predict deep into the futures is severely limited
by the precision of our modelling of these sources and possible other
effects playing in on them. Also, the precision by which we makes the
measures is a limiting factor. Sorting all of this out would
Percent, here, is where the event occurred in the period between the
pulses
Degrees would have helped more.
I think pulsars alone would be difficult for long-term, omni-positional
timing. We haven't even touched on stellar movements over long time periods.
Also, our observation will be in movement from the various sources, so
doppler compensation would be required.
It's not a completely unsolveable thing, but a lot of things shifting
over time throwing in massive of unknown parameters which would need to
be estimated with sufficient precision if we where to build from scratch
the time and time-scale.
Just agreeing on the definitions of the star-book to traverse cultural,
time and position boundaries would be an interesting problem.
Cheers,
Magnus