Re: [time-nuts] How good is the left end of your ADEV curve?

[Henry Hallam]

On Wed, Jan 25, 2017 at 1:35 AM, Volker Esper  wrote:
> What can I do at home, to observe such processes? Or is it way beyond any
> imagination to participate in any such experiments?

It's not exactly direct observation, but you can participate by
joining the Einstein@Home project to use your computer's spare CPU
cycles to search for events in LIGO data (as well as radio and gamma
ray telescopes):

https://einsteinathome.org/

Henry
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Hal Murray]

kb...@n1k.org said:
> ….. errr … would not that be the *right* end of the ADEV curve? …..:)

Argh.  Thanks for the correction.

I got time and frequency swapped in my head, probably because I was thinking 
of the noise vs frequency plots that he showed.

> Back in the 1980’s these guys were after sub 1x10^-15 bumps over path
> distances like Earth to Jupiter. Not sure what they are after these days.

If it's anything like how hard they had to work for LIGO it will be way way way 
out there.  High on the current list of noise sources that LIGO is working on 
is thermal noise from the optical coatings.

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] How good is the left end of your ADEV curve?

[Jim Palfreyman]

I can't recall what I said before, but it *has* been done in the backyard
before. There's good news and bad news. The good news is that all the
software for processing your data: coherent dedispersion, folding, moving
all arrival times to the solar system barycentre, Einstein delay, Shapiro
delay, fitting, analysis etc is open source. You need DSPSR, PSRCHIVE, and
TEMPO2 and a unix machine to run them on.

The bad news:

Vela had a declination of -45 10 35 which means it's not visible very often
for you northerners. The second brightest pulsar has a similar declination.
After that, forget it - they are too faint.

Observing of individual pulses requires around a 20+ m radio telescope with
a receiver cooled to 20K (at ~1400 MHz). However using the above software
you can fold your data on the latest pulse period (which I can provide if
needed) and this then brings things down to a possible level:

You'll need a dish that can track. One that is 2 m across might just work.
Frequency choice is important. The lower the frequency the stronger the
pulse, but also multipath scattering smears the pulse out. Around 1400 MHz
is a good choice for removing the scattering, but may be too faint for
small dishes. If you went with ~600 MHz that could work - but do check any
local RFI.

If you didn't track, but just waited for the pulsar to pass through the
beam, you'd get about 2 minutes of data. That *might* be enough to fold and
get a signal.

It'd be a long, but awesome, project to work on.

The really cool part is that Vela glitches (speeds up) in rotation ~3 years
by around deltaf/f =10^-6 and you could measure that. It just glitched in
December (and I was observing at the time!), so you have another 3 years to
get building.

As to timing, any half decent GPSDO would be fine.

Oh, almost forgot, you'd also need a sampler.


Jim Palfreyman



On 26 January 2017 at 13:58, Tom Van Baak  wrote:

> > What can I do at home, to observe such processes? Or is it way beyond
> > any imagination to participate in any such experiments?
> >
> > Volker
>
> LIGO is a billion dollar experiment, involving thousands of PhD's so it
> will be some time until you can do that sort of stuff alone at home, or
> with your family.
>
> Jim Palfreyman has mentioned before what it would take to do Pulsar
> measurements as a home experiment. Search for the old threads or he can
> jump in to remind us why it can't or hasn't been done yet. See also the
> thread a month ago about a DIY H-masers since you'll want some of them on
> hand before you start.
>
> It's worth spending time reading anything about LIGO. The experiment is
> out-of-this-world clever, complex, sensitive. And it actually works! Unlike
> the particle physics tree, which seems to be nearing the end of bearing
> fruit, LIGO is at the very beginning of an entirely new way to study the
> universe.
>
> /tvb
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Re: [time-nuts] How good is the left end of your ADEV curve?

[jimlux]

On 1/25/17 6:58 PM, Tom Van Baak wrote:

What can I do at home, to observe such processes? Or is it way beyond
any imagination to participate in any such experiments?

Volker


LIGO is a billion dollar experiment, involving thousands of PhD's so it will be 
some time until you can do that sort of stuff alone at home, or with your 
family.

Jim Palfreyman has mentioned before what it would take to do Pulsar 
measurements as a home experiment. Search for the old threads or he can jump in 
to remind us why it can't or hasn't been done yet. See also the thread a month 
ago about a DIY H-masers since you'll want some of them on hand before you 
start.

It's worth spending time reading anything about LIGO. The experiment is 
out-of-this-world clever, complex, sensitive. And it actually works! Unlike the 
particle physics tree, which seems to be nearing the end of bearing fruit, LIGO 
is at the very beginning of an entirely new way to study the universe.



I wonder if there are ways to do this kind of science in a massively 
parallel way.. rather than the "one big awesomely high performing 
instrument" you have a million mediocre instruments...


Of course, I know that doesn't always work, otherwise we could just buy 
1000 cheap crystals and tell the maser folks to peddle their wares 
elsewhere 


But, as in many other endeavors, there's a limit to "how big/fast/good" 
a single device can be, and you have to go to multiple devices - there's 
always complexity and a learning curve, but eventually there is success:



One big power grid tube is better than many smaller ones, but 
eventually, you hit the maximum size tube, and if you need more power 
there's nowhere else to go but multiples.


Scientific computation hit the "single processor" wall, ultimately 
resulting in the development of modern Beowulf cluster computers, which 
in turn forced the development of new algorithms and reformulating the 
underlying problem to allow such large clusters to be useful (Amdahl's 
law, and all), and now things like exascale computing are becoming reality.



I've thought about whether one could do amateur radio Venus bounce or 
Mars bounce, with a distributed transmitter/receiver system, timed by 
GPS, so that you can do coherent processing.



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Re: [time-nuts] How good is the left end of your ADEV curve?

[Tom Van Baak]

> What can I do at home, to observe such processes? Or is it way beyond 
> any imagination to participate in any such experiments?
> 
> Volker

LIGO is a billion dollar experiment, involving thousands of PhD's so it will be 
some time until you can do that sort of stuff alone at home, or with your 
family.

Jim Palfreyman has mentioned before what it would take to do Pulsar 
measurements as a home experiment. Search for the old threads or he can jump in 
to remind us why it can't or hasn't been done yet. See also the thread a month 
ago about a DIY H-masers since you'll want some of them on hand before you 
start.

It's worth spending time reading anything about LIGO. The experiment is 
out-of-this-world clever, complex, sensitive. And it actually works! Unlike the 
particle physics tree, which seems to be nearing the end of bearing fruit, LIGO 
is at the very beginning of an entirely new way to study the universe.

/tvb
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Bob Camp]

> On Jan 25, 2017, at 12:15 AM, Hal Murray  wrote:
> 
> way way way left.
> 
> Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In case 
> you don't recognize the name, he is one of the leaders of the LIGO project 
> that detected gravity waves about a year ago.
> 
> He's a good speaker with a neat topic.  He spent a lot of time giving credit 
> to other people.
> 
> One of the far-out future ideas he mentioned was collecting data on lots of 
> pulsars.  If you could get good enough data, maybe you could see gravity 
> waves wandering around the universe.  (Maybe leftover from the big bang.  I 
> didn't catch that part.)
> 
> The time scale is months or years.  Micro Hertz.  The unit for wavelength 
> would be light-years.

….. errr … would not that be the *right* end of the ADEV curve? …..:)

Back in the 1980’s these guys were after sub 1x10^-15 bumps over path 
distances like Earth to Jupiter. Not sure what they are after these days. 

Bob

> 
> How long will it be before we need a gravity-nuts list?
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Volker Esper]

What can I do at home, to observe such processes? Or is it way beyond 
any imagination to participate in any such experiments?


Volker


Am 25.01.2017 um 06:15 schrieb Hal Murray:

...

How long will it be before we need a gravity-nuts list?



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Re: [time-nuts] How good is the left end of your ADEV curve?

[Jim Palfreyman]

First, a picky - but important - point. There is a difference between
"gravity waves" and "gravitational waves". When you go to the beach and
watch the waves crash on the shore, that's an example of a gravity wave.

Now, onto the far more interesting topic of gravitational waves and my pet
topic, pulsars.

Pulsars most likely give off gravitational waves. The rotate at a rate
anywhere from 1/12 Hz to 716 Hz. The brightest (in a radio sense) and one
of the closest pulsars is the Vela pulsar which rotates at 11.18677266 Hz
(as of a few days back). This frequency is in the sensitivity bands of
Advanced LIGO and Advanced VIRGO, but the gravitational waves from Vela are
probably too "faint" to be detected. But there is still no harm in trying.


Jim Palfreyman



On 25 January 2017 at 16:15, Hal Murray  wrote:

> way way way left.
>
> Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In
> case
> you don't recognize the name, he is one of the leaders of the LIGO project
> that detected gravity waves about a year ago.
>
> He's a good speaker with a neat topic.  He spent a lot of time giving
> credit
> to other people.
>
> One of the far-out future ideas he mentioned was collecting data on lots of
> pulsars.  If you could get good enough data, maybe you could see gravity
> waves wandering around the universe.  (Maybe leftover from the big bang.  I
> didn't catch that part.)
>
> The time scale is months or years.  Micro Hertz.  The unit for wavelength
> would be light-years.
>
> How long will it be before we need a gravity-nuts list?
>
> --
> These are my opinions.  I hate spam.
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
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[time-nuts] How good is the left end of your ADEV curve?

[Hal Murray]

way way way left.

Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In case 
you don't recognize the name, he is one of the leaders of the LIGO project 
that detected gravity waves about a year ago.

He's a good speaker with a neat topic.  He spent a lot of time giving credit 
to other people.

One of the far-out future ideas he mentioned was collecting data on lots of 
pulsars.  If you could get good enough data, maybe you could see gravity 
waves wandering around the universe.  (Maybe leftover from the big bang.  I 
didn't catch that part.)

The time scale is months or years.  Micro Hertz.  The unit for wavelength 
would be light-years.

How long will it be before we need a gravity-nuts list?

-- 
These are my opinions.  I hate spam.



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