Phenomenological probes of quantum gravity: Planck-scale Lorentz-violation; gamma-ray-burst dispersion; primordial gravitational waves; deformed special relativity; GENERAL relativity tests at strong-field. Frontier elevated to PhD-track.
quantum-gravity-phenomenology
Planck-scale Lorentz violation tests
Amelino-Camelia 1998: GZK-cutoff + photon-time-delays from distant GRBs probe E~M_Planck Lorentz-violation. Fermi-LAT 2009 GRB 090510 gives…
GRB photon-dispersion test
Quantum-gravity-induced photon-velocity-dispersion: high-E photon arrives later than low-E by Δt ~ E·D/E_QG. Fermi 2009 / IceCube…
Primordial GWs (CMB B-mode)
Inflation-generated GW imprint on CMB B-mode polarization. BICEP-Planck 2018 constrain r < 0.06. LiteBIRD / CMB-S4 future. Tests…
Deformed special relativity
Magueijo-Smolin 2002: invariant-Planck-energy in addition to invariant-c. Modified dispersion E²=p²c² + m²c^4 + γ E^3/E_QG. Connection to…
Strong-field GR tests + EHT
EHT 2019/2022: M87* + SagA* black-hole shadows match Kerr to ~10%. LIGO 2015- BH-mergers probe ringdown. GW170817 multi-messenger. Test…
Loop quantum gravity phenomenology
Rovelli-Smolin LQG predicts discrete-area-spectrum + holographic-entropy + Lorentz-deformations. Phenomenology: cosmological-bounce +…
String phenomenology + landscape
Susskind 2003 ~10^{500} string-vacua landscape; flux-compactification (KKLT 2003). Anthropic-selection of cosmological-constant. Critique:…
Bekenstein-Hawking BH entropy
Bekenstein 1973 / Hawking 1974: S_BH = A/(4 ℓ_P²). Holographic-bound. Tests of QG must reproduce. Information-paradox: black-hole…
Holographic principle ('t Hooft / Susskind)
't Hooft 1993 / Susskind 1995: degrees-of-freedom in (D+1)-region encoded on D-boundary. Foundation of AdS/CFT + EHT + black-hole-info…
Cosmological constant problem
Vacuum-energy of QFT predicted ~10^{120} larger than observed Λ ~ 10^{-122} M_P^4. Worst prediction in physics. SUSY softens not solves.…
Amplitude bootstrap (modern)
Bern-Dixon-Dunbar-Kosower 1990s / Britto-Cachazo-Feng-Witten 2005: scattering-amplitudes computed without Lagrangian via on-shell methods +…
Equivalence principle tests
Eötvös-MICROSCOPE 2017 weak-EP tested to 10^{-15}. Lunar-laser-ranging strong-EP tested to 10^{-14}. Quantum-tests with cold-atoms…
Planck scale (1899)
M Planck 1899 derived l_P = sqrt(h G/c^3); modern minimum-length-uncertainty hypothesis tested via GW-frequency cutoff.
Modified dispersion (1998)
G Amelino-Camelia 1998 in-vacuo-dispersion observable in gamma-ray-bursts; modern Fermi-LAT + MAGIC constraints E_QG > 7.6 E_Pl linear.
Hawking radiation (1974)
S Hawking 1974 black-hole thermal-radiation T_H = hbar c^3/(8 pi G M k_B); information-paradox + firewall debate ongoing.
Bekenstein-Hawking entropy (1973)
J Bekenstein 1973 + Hawking 1975 BH entropy S = A/(4 l_P^2); modern micro-state-counting in string-theory + holography Maldacena-1997.
GW tests of QG
GW170817 multi-messenger constrains Lorentz-invariance + dispersion; modern LIGO-O4 + LISA-2030s + Cosmic-Explorer probe Planck-scale…
Quantum foam (Wheeler 1955)
J A Wheeler 1955 spacetime-foam at Planck-scale; modern Verlinde 2011 emergent-gravity + Cao-Carroll-Michalakis 2017 entanglement-spacetime.