CEO: Prufessor Vicki $ara

Postal Addfcss: GPO Box 2702 Cwibcn-a ACT 260 I Australia  Street Address: Cnr Jenabombtns Ave and I-liudmarsh Drive  Synionston ACT 260? Australia  Tel: + 61 2 6284 M O O  Fax: + 61 2 6284 6601

7 J;uiu ary 2002

AUSTRALIA’S TIME LORDS

An Australian research t w n  i s  preparing to build a range o f  ticw ‘clocks’ - t h i n g  devices  caiisble of dclivcring the most cxquisitc prccision, 1000 times rtiore accuratc than the  closest coinpeti tor worldwide.

’The clocks,

And, in experiinenls that m y  challcngc prcsent underslanding of thc nature o f  the univcrsc,  they will also he used to test Eir.rstein’s general and special theories or relativity with  unprecedented accuracy - to test the cffecl of‘ gravity on h e ,  and to measim thc s p e d  o r   light 10 see if it really is coi-tstmit.

The tcltiii of 20 rcse;trc;hcrs led by Associate Professors Andrc h i t e n ,  Michael Tohar and  Eugene Ivanov already holds the latirefs for building the world’s most accurate tiinepicce,  their n7icroW3vc-actU;ltCd sapphirc c;lock. Thcy havc bcen asked by the Eurnpcan Spac;e  Agency IO adapl their cloclc so it can fly on the lniernational Spacc Station as part of thc

Atomic Clock Eusernble in Space (ACES) mission during 2006-2008.

“Onc o f  tecllnological reasons for the space missioii is that d.11 the world’s  telecommunications systcms rely c)ii timing with pinpoint accuracy As traffic; builds up  rtiwnd thc globe, it becomes evcr more critical to Syiichi’onisc each country’s time with all  thc others,” (\/Prof. Lititen explrtins.

The ACES mission iiicludos a Frcnch-built ntoinic clock and -because thc atomic clock c;an  only be read every second - the Australian sapphirr: clock must bc there to keep time  between each reading,

1: Lr

I‘he challetige i s  to re-engineer thc sapphire clock so tlarrt it can operate at liquid nitrogcn  iemperutures (minus 136 degrees Celsius) instead of liquid helium (Ininus 269 dcgrces), i l l   order LO reduce the costs o l ~ h o  coolant that niusl bc lifted into orbi4” A/Prof. ‘I‘obar said.

‘The delivery of precision timing at the Jevel of’ 100 t ~ i ~ ~ i o ~ ~ h s  o f  a secaild also offers a  potential revolutiriii in anothcr area - navigatioH, rtsing the satellite-based Cjfobal  Positioning System (GPS). Presently acciirnie cnough to locate a point on the eartli’s  ~wfact: within mctres, ~ h c  hope i s  that prccision timing will enablc location withi)i  mi1l~;tnetres. GPS can then be used for surveying, buildiag and other iniporiarlt activities.

?‘he U WA team i s  also working on a new tinepiece o f  even greater a~cutiticy, ul’tical  oscillators, which produce light sigixds of ta very pure colour.

We use a laser to cool a rnillioil calcium atoihs to just a few tbousandlhs o f  R degree abovc  absolute zcro (minus 273 degrues Celsius). This caiiscs thcm to ‘ring’ at t?. very pyccise  frequency (or coloiu), which can be used to nicasurc lhnc at nn extremely firw scalc.. It’s a n   optical clock.,” said A/Pi-d. Idten.

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Because thc optical clock is governed by the quantum principlcs o f  the microscopic world  and the sapphire clock by ordinary physics, the two tinicpieccs will enable thc r e s c m h x s  to  test some fundanicntai assumptions about nature.

One aim i s  to establish ,whether the speed of light is co.nstaiit or whether - as sonic  astronomers have recently suggested - i r  is staiting to slaw. ffthjs proved to be so, i t  wocdd  radically change the way we perceive the universe.

“‘l‘he astroiiomers are planning to use 20 billion year-old light ,from quasars to mcasutc this.  we hope wc C ~ I I  meamre it using normal light, over a.buut a year,” A/ Prof, 1,uiten says.

Another planned experiment using the two clocks will test whethcr the charge o f  an elcctroti  varics - anothcr fundamental constant that niight cause physics hooks eo be re-writteri if it  proved to be the case.

The precisc comparison of optical and microwave clocks that is essential for thesc typc uf  fundainentril measurements is creating a technological revolution in optical coinnicrniccltions  and spectroscopy” said AIPro V. lvaiiov

v.?

A high-profi le cxperirnent using thc space station clock will put Alhert Einstein’s relativity  theories to the test with 1000 tinies any pi-evious precision. The theory holds that time slows  for a body moving at Iiighcr speed rclativc t~ a slow one, By coniparing il sapphire clock on  tlic space station, moving at ahout 20,000 Itmh”, with otic on carth, the differenct: oug’ht to

be apparent, A/Prof. Liiitcn says.

Mor e info r rn a ti o n :  Dr Andrc h i t e n ,  Wnivcrsity of WA

P n d re@pd, uwa .ed u.au  (08) 9287 1602 (H) 08 9380 7028 (W) 0403 434 085 (M)

