This is a slow liveblog – part II will be tomorrow with more cosmology and life in the universe
Seed funding was provided to 20 investigators and small groups to start exploratory research, and, now, it is time to say what they found.
This follows up from the New Frontiers kick-off conference back in 2012.
The New Frontiers conference to report the hint of the beginning of the draft of the answers is under way… most of the investigators and about half of the student prize winners are here for a couple of days of fairly intense talks and discussion of the progress to date.
@shaka_lulu is tweeting #newfrontiers
- Fossil Remnants of the Universe’s Beginnings: David Chernoff (Cornell)
Look for Cosmic Strings – predicted from inflation plus some guesstimates for phase transitions and and actual theory of strings.
Can be observed in principle – eg through lensing, ought to be finite number of cosmic string loops locally, be interesting to observe to see if we can measure physical parameters eg. string tension.
Model for reasonable theory parameters to see if likely to see string lensing in current or near future surveys.
Short answer: PanStars may see something with a bit of luck; WFIRST ought to see something IF assumptions are correct.
- CosmoArcheology: Richard Holman (CMU)
Looking for “initial state” of universe. CMU team + Sarah Shandera (PSU).
Only looking as far as inflation…
Testing independent/gaussian etc, hoping to look at tensor modes, but caveat BICEP2 – more on that later
maybe– ah yes, Kuo is here – definitely more on BICEP2 tomorrow.
Taking inflation generated quantum modes and mapping them to power spectrum to test allowed initial inflationary states.
More data constrains inflationary models.
Will either find consistent set of inflationary states, or not. (the magic word here is Bunch-Davies vacuum).
Important either way. Cute way of doing this.
- Computing the Wavefunction of the Universe: Kostas Skenderis (Southampton) talking for Alexander Maloney (McGill) – Hartle-Hawking formalism, Wheeler-de Witt equation, using de Sitter/Conformal Field Theory conjecture to get some pieces for the ground state wavefunction
Compute Ψ(h) at future timelike infinity – toy model – anti-commuting, mass-less, non-interacting scalar field under Sp(N). Conformally invariant, natch. High spin excitations.
Result: might be generic – favours topologically complex space times, more degreees of freedom with more complex topologies.
Ought to be generic to holographic theories – that they favour complex topologies.
Interesting if true.
Good job giving someone else’s talk at zero notice!
- Probing the genesis of spacetime using supercomputers: Parampreet Singh (LSU)
Toy model numerical quantization of homogenous spacetime using quantum loop gravity.
Looking at generic singularity avoidance, evolution of perturbative anisotropies etc.
Generic behaviour: see sub-planckian bounce before singularity – seen in localized gaussian states at ρ ~ 0.41 – in suitable units – robust critical density value.
End up with cyclic universes.
Very interesting if physical.
Speculative claims: generic spacetimes – can transition from AdS to dS through evolution, avoiding crunch.
Can avoid singularity in black hole interiors??? – Kantwoski-Sachs spacetime approach to Schwarzschild
- Detecting of Falsifying the Multiverse: David Spergel (Princeton)
Premise: multiverse would likley lead to mixed initial state not pure state ( – so not a Bunch-Davies vacuum – see above).
Possible multiverse signature – oscillations in amplitude of power spectrum driven by mixing, not internal physical evolution of pure state – fiendishly clever – may lead to detectable CMB signal etc.
Meerburg et al:
Searching for Oscillations in the Primordial Power Spectrum: Perturbative Approach (Paper I)
P. Daniel Meerburg (Princeton), David N. Spergel (Princeton), Benjamin D. Wandelt (IAP) Phys. Rev. D 89, 063536 (2014) (arXiv)
Searching for Oscillations in the Primordial Power Spectrum: Constraints from Planck (Paper II)
P. Daniel Meerburg, David N. Spergel (Princeton) Phys. Rev. D 89, 063537 (2014) (arXiv)
Searching for oscillations in the primordial power spectrum
P. Daniel Meerburg (Princeton), David N. Spergel (Princeton), Benjamin D. Wandelt (IAP) Conf Proc 2014 (arXiv)
Interesting low angular mode structure known in CMD power spectrum.
Searching for oscillations in current data.
Computationally hard. Using multinest. Useful for other stuff.
Ran mock data – put synthetic CMB with oscillation into sim and recovered oscillation
Did not see clear signature of oscillations in WMAP9 data given assumptions about how modes might mix. ie they do see oscillations, but the oscillations that they see are consistent with random noise faking you out.
Thinking about other ways modes could mix – eg scalar/tensor, issues of foreground etc.
Power at large angular scales little on low side, low statistical significance.
Physics or bad luck?
Wanna use kinematic Sunyaev-Zeldovich effect to probe. Ah, my favourite!
Co-add and cross-correlate, no way to get individual signature. Use BoSS. Might work.
—-Lunch break with some very diverse and interesting discussion—-
- A holographic theory for the very early universe: Kostas Skenderis (Southampton)
Kostas back with a talk on his own project – looking at non-geometric very early states for (holographic) universe models. I infer.
Perturbative quantum field theory in FRW spacetime breaks down, necessarily, at early times.
Possible to do falsifiable pre-big bang non-geometric theories?
Maybe in holographic framework.
Symmetries to constrain theories, and constraints from data.
—-Now the complexity talks—-
- Emergent Complexity in the Universe: Marcelo Gleiser (Dartmouth)
Information theoretic approach.
Define shannon-like measure of field configurational entropy for bound localized energy configurations (eg solitons, or gravitationally bound systems)
Define configurational entropy, defined over k space – weighted modal fraction
minimize energy and configurational entropy
solutions “bundles or irreducible complexity” – [are they? locally irreducible? globally?]
Questions at that point – short answer: no formal proof, but it works!
- Configurational entropy minimized in nature
- Configurational entropy maximized at instability point of bound state – interesting
- Configurational entropy can be used to detect complext structures
No action principle for configurational entropy, yet.
Very useful if true. Needs some work, potentially very useful.
Other interesting possibilities: configurational entropy as signature of phase transition critical points (first order?) and coupling to external environment issues.
- Cognitive Astrophysics: Barry Madore (Carnegie)
Series of 4 Carnegie-Templeton workshops on Emergence and Complexity etc.
Roundtable closed sessions between astrophysicists and philosophers.
Tutorials followed by Appreciations.
Interesting list of topics and participants… apparently nothing about them online, unfortunately.
Question: are semi-analytic models science? 😉
- Initial Information Folding and Flowing into Complexity: Mark Neyrinck (JHU)
Dark matter fluctuations as source of information.
“Loss of information” (classical) into entropy.
Are there substantial non-primordial information sources?
Structure formation analogous to folding of CDM phase space
Ringing the initial Universe: the response of overdensity and transformed-density power spectra to initial spikes, Mark C. Neyrinck, Lin Forrest Yang (JHU), MNRAS (August 01, 2013) 433 (2): 1628-1633 (arXiv)
Or, Fold your own galaxies HT @shaka_lulu
- The emergence of complex structural patterns: Sergei Shandarin(Kansas)
More phase space folding of dark matter and caustics on submanifolds
We are unable to define complexity consistently – that may not be critical – one these things where diversity may be a virtue.
Bousso proposes that rate of entropy generation is what matters, not absolute amount.
- Testing the Multiverse: Anthony Aguirre (UCSC)
Inflation – one shot or eternal – testable?
Nice graphics… I still want some of those for my class!
For (some) inflation potential, phase transitions can’t “catch up” with rest of space still inflating – hence inflation is unbounded, can be very large, possibly infinite.
That’s when it gets interesting.
NB: each bubble of space-time in the bigger multiverse can itself be infinite. Cute.
Bubbles can collide – ie universe-universe collisions within the multiverse.
This is where potentially testable predictions come in.
Carroll L. Wainwright, Matthew C. Johnson, Hiranya V. Peiris, Anthony Aguirre, Luis Lehner, Steven L. Liebling
“Scientists look for other Universes, find 4″…