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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20140213T103000
DTEND;TZID=Atlantic/Canary:20140213T113000
UID:iactalks-611
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/611
CREATED:2014-02-13T10:30:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:The Hubble Constant: Relieving the Tension
DESCRIPTION:The Hubble Constant: Relieving the Tension\nDr. Barry F. Madore
 \n\nTwenty years ago, no one convincingly knew the age or the size of theU
 niverse to within a factor of two. Ten years ago, everyone agreed onthose 
 same two numbers to within 10%. Today, we arguably have broughtthe errors 
 down by another factor of two. But that has led to anxietyrather than euph
 oria, renewed interest rather than complacency. Theproblem is that there a
 re now two independent, competing methodsgiving answers of comparable prec
 ision and accuracy:one is a model-based method using the cosmic microwave 
 background(the CMB), the other is a geometric, parallax-based method using
  localmeasures of distances and expansion velocities. To within abouttwo-s
 igma the methods agree.  To within about two-sigma the methodsdisagre
 e. And basic physics (a fourth neutrino species, perhaps) hangsin the bala
 nce.I will discuss how this "tension" arose and how it will soon berelieve
 d.  A tie-breaker has been identified and developed, and it isnow bei
 ng worked on from the ground and from space.
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