Archive for October 5th, 2007

Astrophysics: Back in time at edge of the universe

October 5, 2007

On wednesday, I got to hear George Smoot speak. Here are the awesome videos of his lecture with lots of cool visualizations of the universe.

 

The main lesson of his talk was “you can learn a lot about the structure of the universe by observing the fluctuations of the matter, light, etc.” He gave example after example of this in his talk, and explained some of the open questions.

 

According to the big bang theory, the universe started 13.4 billion years ago and has been expanding ever since. For his Nobel prize winning discovery, he used satellite measurements to find variations in temperature from cosmic microwave background (CMB) that provided a detectable signature of the big bang theory. a neat application of astrophysics + thermodynamics + statistics. he proposed this to NASA in 1974 and they finally launched the satellite 15 years later which provided the confirmation. This is his Smooth research group website. They have a new website for learning about cosmology called the Universe Adventure. As I continued to listen to his lecture about the timescales he was talking about measured in billions of years, everything on earth seemed completely insignificant in comparison–that effect lasted on me only for a few hours.

 

Smoot points out that in astrophysics time = distance / speed of light. Telescopes allow us to look back in time because the light we see is coming from such a long distance (millions and billions of light years away) all the way back to the big bang.

 

In the 1960s, Penzias and Wilson at Bell Labs used a satellite to measure microwave radiation and discovered some patterns that indicated they were remnants of the big bang. In 1992, the COBE satellite that Smoot sent up added greater precision and gave unambiguous confirmation of the big bang. Even greater precision was achieved with WMAP in 2003 and PLANCK to be launched in 2008.

 

Smoot explained that scientists learnt a lot about the structure of the sun by observing “ripples” caused by standing waves, which said something about the wavelength and velocity of propagation, and hence the density of the material inside it.

 

Using the Sloan Digital Sky Survey, maps of celestial bodies (stars, etc) all across the universe have been created and their lumpy structure was explained by gravitational attraction influencing the evolution of these bodies when simulations were run on similarly sized objects.

 

The best estimates say that universe consists of

  • 73% dark energy — no idea what this is, maybe a new force of nature

  • 23% dark matter — no light passes through it so we don’t know what it is

  • 4% normal matter

Supernovae are the “standard” candles or guideposts when mapping the universe based on observing their brightness versus time. Their distance can be estimated (calibrated) using the length of the time the star stays bright. Gravitation changes the path of light and that’s how we know about large clumps of “dark” matter. This is called “gravitational lensing.” Observations of light leads to a deconvolution problem to infer the structure of the dark matter.

 

He left the audience with these big questions seeking answers in astrophysics,

  1. What is the right physics to describe the universe?

  2. Did inflation [of the universe] happen? How?

  3. What is the dark matter?

  4. What is the dark energy?

  5. What generated the matter-antimatter asymmetry?

  6. Are there other relics to be found? (e.g. cosmic strings)?

  7. Are there extra dimensions?

  8. Do fundamental constants vary?

  9. What other exotic forces might come into play?

“A World Free of Nuclear Weapons”

October 5, 2007

On January 4, 2007 I stopped at Pete’s coffee on Market Street to get my morning espresso on my daily bike ride, a bit chilly but nothing unusual otherwise. After I sat down I noticed an old gentleman carefully cutting out a newspaper article and putting it in his pocket, as though he was holding something very dear to him–it happened to be,

A World Free of Nuclear Weapons

By George P. Shultz, William J. Perry, Henry A. Kissinger, and Sam Nunn

January 4, 2007; Page A15; Wall Street Journal

Being one of those “I have a dream” kind of ideas, this seemed so far out of left field and most unbelievable until you saw the names of the authors who proposed it–then it was almost certainly unbelievable. It turns out they were bringing back to life a vision that Reagan had discussed with Gorbachev to end the Cold War. This is interesting considering the US has spent some $5.5 trillion dollars on its nuclear arsenal from 1940-1996 according to a report by the Brookings Institution. In the Fall of 2006, I had seen Shultz talk about this concept as part of a Roundtable discussion at Stanford University but back then I didn’t realize to what extent this was being floated as a concrete proposal.

Later in March 2007, I got to see Shultz, Perrry, and Sid Drell explain their vision in person in San Francisco at a panel discussion organized by the World Affairs Council–here are my notes:

  • sid drell was one of the founding members of JASON.
    • during the cold war, he got a letter from andre sakarov (Russian physicist) saying that nuclear weapons pose an “existential threat to humanity,” and ending this threat must be their highest focus.
    • 10 steps outlined in their essay “A World Free of Nuclear Weapons”,
    • Nuclear fuel production = nuclear weapon capability, no two ways about it.
  • Perry classified the risk of nuclear detonation into three categories
    1. miscalculation whose risk has gone to zero (with soviet union, others)
    2. accidental, which still exists. US/Russia are on 15 minute readiness status. ballistic missiles finish the job in half an hour. he shared two stories of near-accidental launches during which he was personally involved
      • Cuban missile crisis. he used to consult for DoD on missiles. one day in 1962 he was called in by his stanford classmate who was deputy CIA director on for an urgent assignment. turned out to be examining photos of soviet missiles in cuba. he dy director would report that to the president every morning. every day during the crisis, he thought that was going to be his last day.
      • as undersecretary of defense, he was woken up by a general who said he saw 200 soviet missiles approaching and had 15 minute window to respond (retaliate). turned out to be false alarm.
      • in both cases, perry attributes the turnaround to good luck rather than good management
    3. nuclear terrorism by non-state actors (Al Qaeda). not as bad as a US-Soviet exchange. he cannot backup of his estimates, but quotes Allison as saying there is a 50/50 chance by the end of the decade.
    4. North Korea is motivated by deterrence, prestige, and economic reasons when seeking nuclear weapons. when perry went to North Korea, he didn’t see anyone from the military. as the top ranked official in the DoD, he asked to meet with NK’s top ranked military officers. the general who came out said he didn’t want to meet. perry asked why they wanted nuclear weapons. the general said they don’t want to be vulnerable to being attacked like in Belgrade (Yugoslavia), and if there were ever a nuclear weapon exploded in Pyongyang, Perry could expect to see one in Palo Alto. So deterrence is a major consideration in NK’s calculus, apart from the economic benefits (i.e. extortion) they are deriving.
    5. If Iran gets nuclear weapons, Egypt, Jordan will certainly follow suit. Israel likely to do a preemptive attack. economic sanctions may convince Iran not to get them. Iran should be offered supply of nuclear fuel to avoid having to build their own fuel production cycle. This will clarify their full intentions (“smoke them out”). Russian and US can offer the fuel, under the authority of the IAEA which is internationally controlled.
    6. what are the uses of nuclear weapons,
      • only use is for preventing MAD with other nations
      • tactical nuclear weapons and bunker busters do not provide enough tactical advantage to justify the risks, as determined by Congress
  • Shultz brings up the historical precedent of how the constitution said “all men are created equal” but it was only centuries later that this vision was fully realized with women and minorities. similarly, he views “world free of nuclear weapons” as an “ought” that we can shoot for and eventually achieve.
    1. when asked what was the most significant turning point during the cold war, Gorbachev told Shultz that it was the Reykjavik meetings where both US/Soviet sides sat down and talked about all the issues.
    2. Reagan
      • called for the abolition of all nuclear weapons. He thought mutually assured destruction (MAD) was inhumane.
      • suggested eliminating long range ballistic missiles and relying solely on strategic bombers which can be called back.
      • Gorbachev asked Reagan why they needed strategic defense—he replied that there could be some other nation (besides Russia) that threatens the US with missiles

Then in April I went to a talk by the world’s most famous historian of nuclear weapons, Richard Rhodes also at Stanford where I learnt a few more things…

Richard Rhodes (4/10/2007), Center for International Security and Cooperation (CISAC), Stanford University

sigfried hecker introduced him—richard’s books teach physics better than most physics texts.

rhodes wrote the most famous books/histories on the US atomic programs called “the making of the atom bomb” and “the making of the hydrogen bomb.” in residence at stanford, rhodes is writing a new book (“arsenals of folly”) on the concept of nuclear abolition that was discussed by Reagan and gorbachev, digging into the motivations of the two leaders.

neils bohr said that the atom bomb puts us in a situation that cannot be resolved by war, requiring a concept of “common security.” it’s analogous to public health. Oppenheimer was a bohr protégé. Soon after the bomb was exploded, hope for international control failed and the strategy shifted to military containment. in the 1960s, the us put aside all priorities to build missiles, including going to the moon. $5 trillion spent on the nuclear arsenal. key political question, how to establish a world system of nuclear restraint?

neocons neglected détente with the soviet union as a fatal move. in 1985, the Cold War was never colder.

Gorbachev was a farmer, won awards, and rose in the ussr to become agricultural minister. He was determined to reduce the cost of defense in order to improve people’s lives. At some point during the cold war it was estimate that the USSR was spending 40-70% of their money on defense.

Reagan a former lifeguard from riverside, saved 70 people, and only wished they would thank him for it. before winning the election, he told one of his presidential campaign managers that his purpose was to end the cold war and eliminate nuclear weapons. only secretary Shultz took him seriously (who was in the audience).

edward teller, father of the hydrogen bomb, proposed the idea of strategic defense initiative (SDI, star wars), i.e. missile defense shield. it could provide an alternative to mutually assured destruction (MAD) and not require aiming nukes at other nations—which Reagan thought was inhuman. Reagan’s vision was to provide SDI to all nations in the world. reagan believed in “common security” as a blueprint for survival.

SDI was used by soviet hardliners to disallow key concessions that gorbachev wanted to make to end nuclear weapons.

“Just as there is no such thing as a machine that doesn’t fail, there isn’t a bomb that doesn’t go off.”

my question to rhodes: define nuclear abolition more precisely. 10,000 à 100 à 1 nuke is very quantifiable. What does 1 à 0 mean? How do you define it independent of time for a nation to assemble/manufacture a weapon or the time to deliver it to its target? Rhodes says the time to arm can be increased up to 3 months (how?), and by doing so the risk of nuclear war can be reduced since that leaves a lot of time to come to a negotiated or conventional military solution.

It would seem that grand visions like this can never happen because the world is a mean place, game theory and animosity rather than cooperation rules the planet. But there is a reason why this might be a good idea as far as self-preservation is concerned–accidents and nuclear terrorism. First, Perry has been pointing out how the risk of accidental launch or other accidents involving nuclear weapons is non-zero–making the benefits of deterrence less than the risk of accidents. The more countries who have nuclear weapons, the more weapons, the greater the risk there could be an accident somewhere. An accidental loss of accounting was just disclosed in the handling of the weapons by the US Air Force–first in 50 years.

Missteps in the Bunker

By Joby Warrick and Walter Pincus
Washington Post Staff Writers
Sunday, September 23, 2007; A01

Second, the more weapons there across many countries, the greater the risk they can fall into the hands of a non-state actor and become part of a nuclear terrorism plot. Almost all US presidential candidates have been outspoken about this threat. In particular, Guiliani has annouced that he wants nuclear detection systems deployed, both across the US border and within the interior.

Toward a Realistic Peace
Rudolph Giuliani
From Foreign Affairs, September/October 2007

An even greater danger is the possibility of a terrorist attack on U.S. soil with a chemical, biological, radiological, or nuclear weapon. Every effort must be made to improve our intelligence capabilities and technological capacities to prevent this. Constellations of satellites that can watch arms factories everywhere around the globe, day and night, above- and belowground, combined with more robust human intelligence, must be part of America’s arsenal. The laudable and effective Proliferation Security Initiative, a global effort to stop the shipment of weapons of mass destruction and related materials, should be expanded and strengthened. In particular, we must work to deter the development, transfer, or use of weapons of mass destruction. We must also develop the capability to prevent an attack — including a clandestine attack — by those who cannot be deterred. Rogue states must be prevented from handing nuclear materials to terrorist groups. Our enemies must know that they cannot murder our citizens with impunity and escape retaliation.We must also develop detection systems to identify nuclear material that is being imported into the United States or developed by operatives inside the country.

Another sign of hope emerged this week when presidential hopeful Obama annouced that he endorses the vision of a world free of nuclear weapons.

Obama Calls for nuclear free world, October 2, 2007, by Lynn Sweet, Sun-Times Columnist

It’s time to junk nuclear weapons, by Ivo Dalder and John Holum, The Boston Globe, October 5, 2007

update: see new op-ed on Jan 15, 2008 “Toward a Nuclear-Free World”. many people continue oppose the drastic changes suggested by this disarmament concept. but besides Shultz, perry, Kissinger, and Nunn, it seems this is also gaining momentum among several current and retired diplomatic and military leaders who are free to speak their mind… Mikhail Gorbachev, Margaret Beckett, Arnold Schwarzenegger, Madeleine Albright, Richard V. Allen, James A. Baker III, Samuel R. Berger, Zbigniew Brzezinski, Frank Carlucci, Warren Christopher, William Cohen, Lawrence Eagleburger, Melvin Laird, Anthony Lake, Robert McFarlane, Robert McNamara and Colin Powell. General John Abizaid, Graham Allison, Brooke Anderson, Martin Anderson, Steve Andreasen, Mike Armacost, Bruce Blair, Matt Bunn, Ashton Carter, Sidney Drell, General Vladimir Dvorkin, Bob Einhorn, Mark Fitzpatrick, James Goodby, Rose Gottemoeller, Tom Graham, David Hamburg, Siegfried Hecker, Tom Henriksen, David Holloway, Raymond Jeanloz, Ray Juzaitis, Max Kampelman, Jack Matlock, Michael McFaul, John McLaughlin, Don Oberdorfer, Pavel Podvig, William Potter, Richard Rhodes, Joan Rohlfing, Harry Rowen, Scott Sagan, Roald Sagdeev, Abe Sofaer, Richard Solomon, and Philip Zelikow.