Time Dilation tinkering
Am 22.03.2017 um 15:56 schrieb jimlux:
On 3/22/17 4:04 AM, Angus wrote:
On Tue, 21 Mar 2017 13:08:56 +0100, you wrote:
On Tue, 21 Mar 2017 13:38:51 +1100
Hugh Blemings hugh@blemings.org wrote:
This got me to wondering if a Rubidium based standard might do the
trick
- the Efratom SLCR-101s seem readily available for ~USD$200 mark.
As TvB wrote, a single one will not do the trick. You will need
a stability 1e-14 @1d. IIRC most Rb standards floor out at 1e-12 to
1e-13
somewhere between 1k and 100k seconds. Even the Super-5065 has a floor
of about 3-4e-14 (unless our friends here improved on this already).
There will be a few things that you will need to do, if you want to go
with Rubidiums:
- Stabilize or compensate for environmental effects (temperature,
air pressure) - Build ensembles of Rb clocks.
Hi,
Looking back at an old plot I did of a temperature controlled and air
pressure compensated LPRO against an M12+T, the Hadamard Deviation of
the 1000s averages of the 1PPS measurement was about 5E-14 at 1 day.
A large part of that was likely the GPS, so with a better rubidium
like an FRK-H in a sealed and temperature controlled enclosure you
might be around 1E-14 at 1 day.
The bit that I'm not so sure about is the travelling. A long period of
movement, vibration, magnetic fields, etc. all adding in could
obscure the effects of time dilation.
It might be quite possible, although a nearby mountain and a friend
with a helicopter would make it a lot easier!
No tall mountains in Australia, but...
Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of
course the base is at about 5000 ft/1600 m
In EU, there's probably a Seilbahn of some sort pretty high up in the
Alps, although probably not to 4000m.
I like the englisch word 'Seilbahn' ;-)
Yes, not fully up to 4000 m, but there are in fact quite close to the
possibilities I know:
-
Klein Matterhorn, Walliser Alpen, Schweiz
Bergstation: 3820 m, -
Aiguille du Midi, France
Télépherique de l’Aiguille du Midi
from Chamonix
Bergstation: 3777 m
Gourmet-Restaurant, 3842 m
Enjoy, good luck!
Arnold
On 3/21/2017 7:12 PM, Chris Albertson wrote:
"flight" there is the word. Why drive up a mountain? Take the clock
with you inside the pressurized cabin of a commercial airliner next time
you are on one of those 10 hour trans=pacific flights. You be taller then
any mountain and it is actually cheaper then a weather balloon.
Yes Len Cutler did that 50 years ago, but the velocity of the plane also
has relativistic effects, so it's not a pure play.
Rick
Hi,
On 03/22/2017 12:02 AM, Tom Van Baak wrote:
Scott McGrath wrote:
Or perhaps use the Symmetricom CSAC ...
Chris Albertson wrote:
Get a weather balloon. Or there might already be an amateur group that
launches these. Balloons can go much higher than your local mountains.
You'll both be interested to hear that CSAC+balloon was proposed for the "Genius by Stephen Hawking" TV program and, yes, we were in touch with amateur high altitude balloon groups. The producer rightly thought that a small atomic clock going up in a helium balloon would make dramatic video for a time dilation demonstration. Symmetricom / Microsemi donated a SA.* series clock to the effort.
I got involved on the science and engineering side of the equation. Spent a month trying to make it work and in the end the balloon idea was dropped. Just too hard, and too uncertain, and would require many more months of R&D, and finger crossing. So that's why, instead, I drove six calibrated 5071A down to Tucson for a conventional mountain-valley time dilation experiment -- which I knew from prior experience would work, especially with 3x redundancy. http://leapsecond.com/great2016a/
Note that miniature Rb and Cs clocks (such as those sold by Microsemi) are very small, ultra light, and amazingly low power -- but their long-term stability (including environmental effects) is a hundred or even a thousand times worse than a 5071A/001. This is not to say CSAC are poor clocks. In fact they have a superb mass/power/size to adev ratio, and thus there are many unique applications for them. But they are not designed to be laboratory-quality frequency standards
Indeed. CSAC is a superb clock for the power it consumes, and that is
the market segment it attempts to address. For the same size and more
power, you get much better stability. Just because it has Cesium doesn't
make it a laboratory clock, it's a small gas-cell, with all the issues
of one.
Which reminds me, I got three CSACs to measure. Into the lab I go.
Cheers,
Magnus
On Wed, Mar 22, 2017 at 07:52:38AM -0700, jimlux wrote:
I imagine there's a "de minimis" quantity. We didn't declare the cesium in
the CSAC that we hand carried, and I'm pretty sure people have hand carried
SRS Rb sources.
The letter they have covers anything up to a gram of Rb.
Certainly I'm not worried about it, I hand carry all sorts of things on
planes.
off of the MSDS from Symmetricom/Microsemi
"All Symmetricom’s rubidium product can be shipped both domestically and
internationally as a non-hazardous product. Symmetricom has received letters
of interpretation from both the United States Department of Transportation
(US DOT)Ref. No. 08-0154 and the International Air Transport
Association(IATA) stating that Symmetricom’s rubidium product are not
considered a hazardous Class 4 material in transportation.
2008 letter and response here:
https://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/Files/Interpretation%20Files/2008/080154.pdf
--msa
On 3/22/17 10:07 AM, Arnold Tibus wrote:
No tall mountains in Australia, but...
Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of
course the base is at about 5000 ft/1600 m
In EU, there's probably a Seilbahn of some sort pretty high up in the
Alps, although probably not to 4000m.
I like the englisch word 'Seilbahn' ;-)
Well, the equipment is all made by German speaking companies, even in
the US, so it seems an appropriate term. Cable Car or Gondola aren't a
unique description (i.e. Cable Cars in San Francisco and Gondolas in Venice)
Yes, not fully up to 4000 m, but there are in fact quite close to the
possibilities I know:
-
Klein Matterhorn, Walliser Alpen, Schweiz
Bergstation: 3820 m, -
Aiguille du Midi, France
Télépherique de l’Aiguille du Midi
from Chamonix
Bergstation: 3777 m
Gourmet-Restaurant, 3842 m
Now that I think about it, though, speed of transit isn't as important
as "length of time at altitude", because if we're following tvb's GREAT
experiment, you have some clocks you leave at the low elevation, then
some clocks you take high for while, then bring back low, and you
compare the apparent "elapsed time". So longer duration helps increase
the delta (but also, of course, adding to the variance of the two
measurements, so there's a tradeoff).
So, are you better off with a week long camping trip at a moderate
altitude, or a 14 hour flight at 10-15,000 meters. Or would you take a
small battery powered package up to the Bergstation and leave it there
for a week?
The airport in La Paz, Bolivia is at around 4000 meters, the city itself
at 3600m.
With relatively inexpensive atomic clocks, could one, with clever
mailing addresses, send two clocks the opposite directions around the
earth, and duplicate the famous traveling clocks experiment. For
instance, with a collaborator in Australia or India, EU, and US, you
could probably arrange for the packages to go the "correct" direction.
Hi,
On 03/22/2017 05:55 PM, Attila Kinali wrote:
On Wed, 22 Mar 2017 07:56:45 -0700
jimlux jimlux@earthlink.net wrote:
In EU, there's probably a Seilbahn of some sort pretty high up in the
Alps, although probably not to 4000m.
But almost: https://en.wikipedia.org/wiki/Klein_Matterhorn
You could start in Sion(500m) or Visp(660m) take the train to Zermatt(1600m)
and from there the cablecar up to Klein Matterhorn(3880m). That would
give a nice 3000m of height difference. From Sion it takes 2.5h to 3h,
from Visp 2h to 2.5h. So you could potentially get up in the morning,
go up, install everything and be back for dinner :-)
If anyone wants to do that, please let me know. :-)
We both where uhm. kind of "volunteered" for a similar mission.
I would not mind a little "vacation" like that.
Cheers,
Magnus
On Wed, Mar 22, 2017 at 9:39 AM, David C. Partridge
david.partridge@perdrix.co.uk wrote:
Aiguille du Midi is 3842m IIRC (cable car base station at about 1000m).
Dave
Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of course the base is at about 5000 ft/1600 m
In EU, there's probably a Seilbahn of some sort pretty high up in the Alps, although probably not to 4000m.
Mauna Kea in Hawaii lets one drive from sea level to 13,796 ft, 4204
m. Pretty big delta for a few hours of over land travel.
On 22/03/2017 10:56 AM, jimlux wrote:
On 3/22/17 4:04 AM, Angus wrote:
No tall mountains in Australia, but...
Pikes Peak in the US is 14114 ft, 4304m and has a road to the top. Of
course the base is at about 5000 ft/1600 m
In EU, there's probably a Seilbahn of some sort pretty high up in the
Alps, although probably not to 4000m.
I've driven a few passes in Colorado above 10,000 and one above 12,000.
Four are above 12,000 ft, highest at 3,712 metres (12,183 ft).
https://en.wikipedia.org/wiki/List_of_mountain_passes_in_Colorado
Nine of those are higher than the top of the Eiger.
http://www.dangerousroads.org/rankings23/1610-highest-paved-road-list-in-usa.html
If it's the difference in height in a day, one option in Switzerland is
the cog train to the Jungfraujoch. That's 3,466 metres (11,371 ft). The
Jungfraubahn is listed as 3,454 metres (11,332 ft). It's not cheap; with
my ski pass, I never went beyond the Eigergletscher.
You could start from Grindelwald at 1,034 m (3,392 ft) or from
Lauterbrunnen at 802 m (2,631 ft).
You can drive to either from Interlaken, and there used to be a train,
so you could start from 566 m (1,857 ft).
Michael
Chris Albertson wrote:
Why drive up a mountain?
"Because it's there" ;-) And because there's a paved road, and it's free, and there's a place to stay overnight, and the mountain doesn't move. Plus a car makes a good portable time lab; you can share the experience with family or students or visiting time nuts; and a number of technical reasons.
But most importantly: you can remain at altitude as long as you want -- in order to accumulate just enough nanoseconds of time dilation to meet your experiment's S/N goal -- without running into (or much worse, going beyond) the flicker floor of your clocks.
There are several different ways to measure time dilation with atomic clocks. Some notes here:
http://leapsecond.com/pages/atomic-tom/
Take the clock with you inside the pressurized cabin of a commercial airliner
Yes, and this has been done many times. The first (1971) and most famous of all traveling clock relativity experiments is:
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
For vintage hp flying clock articles see:
https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
Two modern examples are described here:
"Time flies"
http://www.npl.co.uk/news/time-flies
"Demonstrating Relativity by Flying Atomic Clocks"
http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
/tvb
----- Original Message -----
From: Chris Albertson
To: Tom Van Baak ; Discussion of precise time and frequency measurement
Sent: Tuesday, March 21, 2017 7:12 PM
Subject: Re: [time-nuts] Time Dilation tinkering
"flight" there is the word. Why drive up a mountain? Take the clock with you inside the pressurized cabin of a commercial airliner next time you are on one of those 10 hour trans=pacific flights. You be taller then any mountain and it is actually cheaper then a weather balloon.
Can you get a Rb clock past the TSA x-ray machine. Maybe if you ask first. There must be a way to hand cary specialized equipment.
On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak tvb@leapsecond.com wrote:
But attached is one of the first plots where I put a SA.32m in a home-brew vacuum chamber and pulled down to a few inches of Hg for a few hours to simulate the low pressure of a flight up to 50 or 90,000 ft. For a high altitude relativity experiment -- where you'd like your clock to remain stable to parts in e-13 and not accumulate too many stray ns -- it's not a good sign when your clock changes by 2e-11 (that's more than 1 ns per minute) just because of ambient pressure changes.
It's not getting one past the airport authorities that's the issue. It's getting one that's powered up past them. ;)
Written from about 10,000'. :)
On Mar 22, 2017, at 20:15, Tom Van Baak tvb@LeapSecond.com wrote:
Chris Albertson wrote:
Why drive up a mountain?
"Because it's there" ;-) And because there's a paved road, and it's free, and there's a place to stay overnight, and the mountain doesn't move. Plus a car makes a good portable time lab; you can share the experience with family or students or visiting time nuts; and a number of technical reasons.
But most importantly: you can remain at altitude as long as you want -- in order to accumulate just enough nanoseconds of time dilation to meet your experiment's S/N goal -- without running into (or much worse, going beyond) the flicker floor of your clocks.
There are several different ways to measure time dilation with atomic clocks. Some notes here:
http://leapsecond.com/pages/atomic-tom/
Take the clock with you inside the pressurized cabin of a commercial airliner
Yes, and this has been done many times. The first (1971) and most famous of all traveling clock relativity experiments is:
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
For vintage hp flying clock articles see:
https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
Two modern examples are described here:
"Time flies"
http://www.npl.co.uk/news/time-flies
"Demonstrating Relativity by Flying Atomic Clocks"
http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
/tvb
----- Original Message -----
From: Chris Albertson
To: Tom Van Baak ; Discussion of precise time and frequency measurement
Sent: Tuesday, March 21, 2017 7:12 PM
Subject: Re: [time-nuts] Time Dilation tinkering
"flight" there is the word. Why drive up a mountain? Take the clock with you inside the pressurized cabin of a commercial airliner next time you are on one of those 10 hour trans=pacific flights. You be taller then any mountain and it is actually cheaper then a weather balloon.
Can you get a Rb clock past the TSA x-ray machine. Maybe if you ask first. There must be a way to hand cary specialized equipment.
On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak tvb@leapsecond.com wrote:
But attached is one of the first plots where I put a SA.32m in a home-brew vacuum chamber and pulled down to a few inches of Hg for a few hours to simulate the low pressure of a flight up to 50 or 90,000 ft. For a high altitude relativity experiment -- where you'd like your clock to remain stable to parts in e-13 and not accumulate too many stray ns -- it's not a good sign when your clock changes by 2e-11 (that's more than 1 ns per minute) just because of ambient pressure changes.
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