Nobel Prize to Mather and Smoot for CMB Anisotropies

By Sean Carroll | October 3, 2006 10:40 am

COBE The Nobel Prize in Physics has been awarded to John Mather and George Smoot, for their discovery using the COBE satellite of temperature anisotropies in the cosmic microwave background. (Update: To be more accurate, Mather won the prize for measuring the blackbody spectrum of photons, announced in 1990; Smoot won it for measuring the anisotropies, announced in 1992. Thanks to Ned Wright for pointing out my sloppiness.) These tiny fluctuations in temperature provide a high-precision snapshot of what the universe was like 380,000 years after the Big Bang. They originate in density fluctuations that grow into large-scale structure today, and subsequent careful examination of the properties has revealed a tremendous amount about our universe. It’s a very well-deserved Nobel, which was top on my list of potential cosmology prizes back in May:

The 1992 observation of CMB anisotropies by NASA’s COBE satellite was the first step in a revolution in how cosmology is done, one that has come to dominate a lot of current research. Subsequent measurements by other experiments have obviously led to great improvements in precision, and most importantly extended our understanding of the anisotropies to smaller length scales, but I think the initial finding deserves the Nobel. So to whom should the prize be awarded? On purely scientific grounds, it seems to me that there was an obvious three-way prize that should have been given a while ago, to David Wilkinson, John Mather, and George Smoot. Wilkinson was the grandfather of the project, and was the leading CMB experimentalist for decades. Mather was the Project Manager for the satellite itself (as well as the Principal Investigator for the FIRAS instrument that measured the blackbody spectrum), while Smoot was the PI for the DMR instrument that actually measured the anisotropies. Unfortunately, Wilkinson passed away in 2002. Another complicating factor is that there were various intra-collaboration squabbles, leading to books by both Smoot and Mather that weren’t always completely complimentary toward each other. Still, background noise like that shouldn’t get in the way of great science, and these guys definitely deserve the Nobel.

When the results were announced in 1992, I was a fourth-year graduate student at the Center for Astrophysics at Harvard. Somehow, despite great attempts at secrecy, Bill Press had received a leak about the upcoming announcement, and had told some of us at CfA. The next day I went to the Physics colloquium and was the first to spread the news to some of the famous physicists chatting in the tea room, like Sidney Coleman and Roman Jackiw. My first feeling of being a cosmology insider.

It was a funny discovery, in the sense that most everyone expected that it would come (COBE was designed to do exactly this), and nevertheless ended up revolutionizing the field. The simplest measure of this was the arrival of an entire generation of smart young theoretical cosmologists who got their Ph.D.’s in the 1990’s working on the implications of the CMB anisotropies. Whenever we learn alot about the universe, of course, we also start ruling out interesting ideas; these days, nobody proposing a new cosmological scenario will be taken seriously unless their model is compatible with the microwave background.

Congratulations to John and George for ushering in the Golden Age of Cosmology!

  • nc

    This is a sensible and proper award and congratulations to Mather and Smoot.

    Hopefully, by now most people will have forgotten George Smoot’s initial hype about seeing the “face of God” in the COBE data, so he won’t get attacked as an IDer …

  • JD

    My only question is whether we can get another “Smoot” unit named for George Smoot rather than Oliver Smoot. This one could be a unit of angular resolution.

    Just think, we could confuse generations of astronomy students!

  • Tom Renbarger

    I get to request a blog entry at Uncertain Principles for boldly predicting Smoot and Mather (and Wright, couldn’t remember the DIRBE PI) over there, just as I’ve done each of the past few years.

  • Plato

    It must of been on your mind?

    That’s P…um…L-A-T-O :)

    I noticed Smoot’s Group link. And, on cosmic strings too?:)I think that has been resolved?

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  • anon

    Congrats to only Smoot and Mather? I dont want to sound ornery about this (since I think they deserve the prize as such things go), but isn’t it that they were heads of large groups of people, all of whom contributed and spent effort on obtaining the experimental results?

  • PK

    Yes, that’s often the trouble with the Nobel prize these days. But what can you do? Perhaps they should offer it to collaborations? However, this will lower the impact of the prize.

    Nevertheless, I am very happy that Mathers and Smoot got it. As Sean explained, the COBE data transformed the field, and isn’t this exactly what the Nobel prize is designed to reward?

  • Joe Fitzsimons

    Am I wrong in thinking that the IAEA as a whole got the piece prize last year? Surely that would be a precedant for giving the prize to a large organisation.

    That said, I do think it would take away from the impact of the award, as PK has mentioned.

  • Abi

    This story has some interesting snippets of discussions in Nobel committees for medicine, chemistry and physics.
    The reporter claims that these snippets are based on “open sources and interviews with knowledgeable persons outside the committees”.

    Mather and Smoot feature prominently in one of the conversations.

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  • fh

    Joe F, the peace price has gone to organisations numerous times. Looking it up: The Permanent International Peace Bureau, the International Red Cross (3 times), Nansen International Office For Refugees, The Friends Service Council, UNHCR, ILO, UNICEF, Amnesty International, International Physicians for the Prevention of Nuclear War, United Nations Peace-Keeping Forces, ICBL, Medicines Sans Frontiers, the UN, and finally the IAEA.

    But these are organizations not collaborations, and none of the other nobel prizes can be awarded to an institution AFAIK, they can, at most, be split three ways.

  • Dark Vader

    Congratulations to John Mather and George Smoot for The Nobel Prize in Physics 2006!

    CMB (Comic Malapropism Background): Smoot question – Does it really matter if the early universe matter was perfectly smooth or not? Mather – It does matter! With perfectly smooth matter, there will be no smoot nor mather! 😮

    And now, something (almost) completely different: I was a happy camper after comment #176: Skeptic23 in post Dark Matter Exists, but now the Devil’s Advocate has contacted me with some outrageous questions regarding CMB, hot x-ray gas and Dark Matter.

    Skeptic23 pointed out: “…we do not have any observations of cluster-sized groups of galaxies without the hot x-ray gas”. Hence, the universe is jam-packed with galaxies in clusters, accompanied by hot x-ray gas (with temperatures of tens of millions of degrees), and this doesn’t work in my brain:

    1) How on earth can COBE and WMAP measure temperature anisotropy in CMB (2.73 Kelvin), at a level of one part in 100000, if they have to look through a (compact on large-scale) “smog” of hot x-ray gas of tens of millions of degrees? Don’t tell me – CMB and x-ray gas is at different “heat-wavelengths”, …or what??

    2) The (bullet)proof for Dark Matter requires the companion of millions of degrees of hot x-ray gas in the galaxies clusters. If hot x-ray gas encloses the clusters/galaxies/stars/planets – how can there be chickens living in Kentucky (not fried yet)? Don’t tell me – Kentucky is an exception from the rest of the universe, …or what??

    3) Maybe stars can “protect” planets from hot x-ray gas by making “wormholes” in the gas (by gravity?). But the collision in Galaxy Cluster 1E 0657-556, with the galaxies moving right through two colliding hot x-ray gas clouds (generating even higher temperatures) – must have over-fried any Kentucky Chicken still alive in the neighborhood, …or what??

    Please any professional, help me with this one and I promise not to talk to the Devil’s Advocate again!!

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  • Charon

    Dark Vader:

    1) X-ray observation and (microwave) CMB observations are indeed at very different wavelengths. Hot intracluster gas (ICM) also radiates via thermal brehmsstrahlung, rather than as a blackbody like the CMB (or a star). Also, there are an insanely large number of CMB photons relative to anything else (more CMB photons than from stars, AGN, ICM, etc. put together).

    2) The density of the hot interstellar medium (ISM) in our galaxy is roughly 10^-3 particles/cm^3. The density of air on the surface of the Earth is roughly 10^25 particles/cm^3. See why the ISM doesn’t matter to most non-astronomers?

    3) Forget wormholes, see 2).

  • Dark Vader

    Thanks Charon!

    The Universe is fantastic and weird, and I feel it’s maybe over my capability to comprehend. Temperatures of tens of millions of degrees in ICM, but so scattered you won’t feel a thing? Huum, it’s magic…

    Completely unscientific calculations:
    “Power density”/cm^3 of Earth-air at 300° Kelvin = 3 x 10^27
    “Power density”/cm^3 of ICM = 10^7 x 10^-3 = 10^4

    So, the ICM on Earth “heats” the air by a factor of 0,0000000000000000000000033 / cm^3 !? Obviously not enough to frie Kentucky Chickens… :-)

  • Paul Valletta

    If COBE and WMAP ar cased within their own tempeature dependant apparatus, ie if COBE for instance was a detector cooled/encased with a temp field of about -273 degrees, then it could not possably detect anything lower than its local themal signiture?

    Long wave detectors operate at certain wavelengths, the componants of which must be giving off a certain amount of thermal heat, how does it filter this heat away from what it is supposed to be detecting?

    I mean, it is contaminated at close range?

    For WMAP it operates (as I understand) a detector of far-off, back in time, differences in background radiation.

    Same thing, what about the local “foreground” pollution that the detector itself must be giving off?

    This is where I think I am mistaken, so if so please correct, Radio waves cover a certain distance, they are LONG, if they are intercpted by any shorter wavelength (any hotter body), then the Long wave shortens as it absorbs the incoming energy, thus a Longwave will be more susseptable to contamination?

    If, in simplistic terms, there is a High Energy Photon that hits a body that is say, just about -273k..then it must transmit part of its thermal energy, to raise the -273 k up by a discrete factor?

    If one throws a cool flask into a hot volcano, what get heated and what gets cooled!

  • Dark Vader

    Paul Valletta, I don’t know about close range contamination of CMB (cosmic microwave background radiation), but the anisotropy of CMB seems to bee affected by a long distance scattering phenomena due to ICM (intracluster medium), which is a superheated gas (10^7 to 10^8 Kelvin) present at the center of most galaxy clusters. You can read more about the SZ Effect (Sunyaev-Zel-dovich effect) on this page.

  • Dark Vader

    (…The Party Pooper is back…)

    Corrupted Echoes From the Big Bang?

    As a layman it’s overbold (read crazy) to question the brand-new Nobel Prize in Physics. But, I can’t help feeling a little bit spiteful since Charon in a professional way squashed my earlier thoughts about CMB and ICM complications. :-)

    According to Prof. Tom Shanks in the Physics Department at the University of Durham THERE ARE indications of ICM corrupting CMB!

    “The team has found that nearby galaxy clusters appear to lie in regions of sky where the microwave temperature is lower than average. This behaviour could be accounted for if the hot gas in the galaxy clusters has interacted with the Big Bang photons as they passed by and corrupted the information contained in this echo of the primordial fireball.” — Prof. Tom Shanks

    Full report: Are Galaxy Clusters Corrupting the Echoes from the Big Bang?

    Pictorial evidence: Evidence for an Extended SZ Effect in WMAP Data

    I’m not the man to judge if this is serious science or intelligent-designer-bullshit. Would be fun to hear some pros comment on this.

    (And Sean, this undermines the previous evidence for both dark energy and dark matter!!)

  • Dr. Margiani

    You can choose many interesting topics in my site for you. -Subject- new Theory about evolution in the universe…

  • Dark Vader

    Sorry, Dr. Margiani even as a layman I do realize that this is not science, disqualifying in the very first sentence:

    “I have written this book for the mankind, because they may die in a few days as the dinosaurs. Then the whole Earth will be the kingdom of the Zalambdalestesses-like rats and mice.”

    The first obvious legitimate question: If your theory were correct, who would read your book in a few days – rats or mice?



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About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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