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IAS IAS April 9, 2008April 9, 2008
Lawrence Rudnick, University of Minnesota Lawrence Rudnick, University of Minnesota in collaboration with Shea Brown & Liliya Williamsin collaboration with Shea Brown & Liliya Williams
A UniverseA UniverseFull ofFull of
NOTHINGNOTHING
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EVERYWHERE, EMPTINESS air, atoms, stars, universe
WHAT WE DON’T SEE
THE CURIOUS VACUUM
FINDING the BIGGEST NOTHING
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EVERYWHERE EMPTINESS
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AIR
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INTO THE ATOM
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Lord Ernest Rutherford1911 Gold Foil Experiment
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PLANETS & STARS PLANETS & STARS
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The 3-D Universe: TIME & SPACE
0.0001 sec
100’s years
5 min
1000’s years
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Looking back – time and space
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Structures in the Universe
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Words Words of of
WisdoWisdommThe Universe is almost empty,
from sub-atomic to cosmic scales
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WHAT WE DON’T SEE
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“DARK” Matter
Behind the scenes…
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“DARK” Energy
Behind the scenes…
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Behind the scenes...
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Words Words of of
WisdoWisdomm
The Universe is almost empty, from sub-atomic to cosmic scales
The most important stuff is what we DON’T see (dark matter & energy)
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THE CURIOUS THE CURIOUS VACUUMVACUUM
“That gravity should be innate, inherent and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no competent faculty of thinking, can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers.” I. Newton, 25 Feb, 1693
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• Making a vacuum
• The luminiferous aetherwhat medium carries light?
• What’s left in the vacuum?
THE CURIOUS THE CURIOUS VACUUMVACUUM
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Evangelista Torricelli 1640s
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Von Guericke – the Magdeburg spheres (1654)
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WHAT CARRIED THE LIGHT?
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Michelson-Morley 1881, 7
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Is the vacuum empty?
The vacuum is that which is left in a vessel after we have removed everything from it that we can remove from it. James Clerk Maxwell 1892
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Vacuum Waves
• Casimir effect: 1948
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Vacuum Waves
• Casimir effect
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Radioactive Decay
210Po 206Pb + 4He
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E*t > h/2
Radioactive Decay
energy from the vacuum
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Have we reached the ultimate vacuum?
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Words Words of of
WisdoWisdomm
The Universe is almost empty, from sub-atomic to cosmic scales
The most important stuff is what we DON’T see (dark matter & energy)
Even the vacuum is teeming with forces (dark energy) that dominate the dynamics of the Universe
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FINDING THE BIGGEST NOTHING
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Early Universe – first look
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+0.0001
-0.0001
-0.25
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1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 381 400 419 438 457 476 495 514 533 552 571 590 609 628 647 666 685 704 723 742 761 780
-2.5
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1 19 37 55 73 91 109 127 145 163 181 199 217 235 253 271 289 307 325 343 361 379 397 415 433 451 469 487 505 523 541 559 577 595 613 631 649 667 685 703 721 739 757 775
-25
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1 19 37 55 73 91 109 127 145 163 181 199 217 235 253 271 289 307 325 343 361 379 397 415 433 451 469 487 505 523 541 559 577 595 613 631 649 667 685 703 721 739 757 775
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1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 381 400 419 438 457 476 495 514 533 552 571 590 609 628 647 666 685 704 723 742 761 780
-2500
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1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 381 400 419 438 457 476 495 514 533 552 571 590 609 628 647 666 685 704 723 742 761 780
Ear
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Early Universe – a fine look
WilkinsonMicrowaveAnisotropyProbe
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Isolating the CMB Cold Spot
Early Universe
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Hole in the NVSS
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Early Universe “Local” Universe
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Late Integrated Sachs-Wolfe (ISW) Effect
EnergyEnergyEnergyEnergy
• A CMB photon will change energy as it traverses a potential well
• -- if the well evolves during the transit.
f
iISW
rdrT
T),(2
Peebles & Ratra 2003
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Void Statistics
• Very unlikely given the current void statistics, such large scales have not been investigated either in observations or simulations
Hoyle & Vogeley 2004
Average: δ = -0.94±0.02; R=(15.61±2.84) h-1 Mpc
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I love talking about nothing. It’s the only thing I know anything about. (OW)
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Olber’s paradox
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“LOCAL” UNIVERSE
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How Large of a Void is Needed?
• We can do an order of magnitude calculation to find the size of the void need to create the “cold spot”
• If we assume δ = -1 and z = 0.5-1.0, we calculate that a ~280 Mpc void is need.
• Void statistics done so far find that the probability of finding a 280 Mpc void is ~5x10-10
• Second order effects could change the size of the void(s) needed Inoue & Silk 2006, 2007
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What we’ve learned...
• CMB has tiny fluctuations from Early Universe, (at 46 billion light years away) plus mysterious “cold spot”
• There is a “deficit” of radio galaxies in the same direction as the cold spot (6-10 billion light years away)
• If the radio galaxy deficit is due to an empty void, 1 billion light years across, it could be responsible for the WMAP cold spot.