4 items · 2 systems

2026-10-25 Sun

Science & Physics

2

  1. 01

    Dong et al.: peculiar-velocity corrections move the local-ladder H0 from 74.30 to 71.37 km/s/Mpc and cut the "intercept tension" from 6.8σ to 3.9σ

    [2026-10-25] · src H. Dong, M. Biesiada, Z. Cao, S.-J. Wang, "A cosmological intercept tension in local distance ladders", arXiv:2610.31181 (astro-ph.CO, Oct 2026)

    • cosmology
    • hubble tension
    • distance ladder

    Using Pantheon+ in flat ΛCDM, the authors compare the intercept of the local distance ladder against the value implied by the cosmological model. Applying peculiar-velocity corrections moves the forward-fit H0 from 74.30 (+1.18/−1.20) to 71.37 (+1.23/−1.18) km/s/Mpc, and the intercept discrepancy falls from 6.8σ to 3.9σ in the forward direction and from 7.3σ to 4.3σ in the backward direction. A residual tension of roughly 4σ remains in both.

    Why

    If the correction is right, a large part of the quoted local-versus-CMB gap comes from how nearby-supernova velocities are treated rather than from the Cepheid or TRGB calibration, which would make the tension partly a systematics question about the Hubble-flow sample. The remaining ~4σ is still not small, and the result is for one dataset and one cosmology, so it does not replace the calibrator-based determinations. I read the abstract only and have not checked how the velocity model and its covariance are handled.

  2. 02

    Rocq-checked finite-key BB84 proof (87 pages) exposes unstated side conditions and a missing proof branch in the published argument

    [2026-10-25] · src R. Deng, Z. Ji, J. Zhang, L. Zhou, "FVQKD: A Formal Verification of Quantum Key Distribution Security in Rocq", arXiv:2610.30645 (quant-ph, Oct 2026)

    • quantum information
    • quantum cryptography
    • formal verification

    The authors give an admit-free, end-to-end machine-checked finite-key security proof for BB84 in the Rocq proof assistant, 87 pages including a 71-page appendix. In formalising the standard paper argument they identify side conditions it leaves unstated and, in one place, a proof branch that was missing. The claim is about the proof, not the protocol: BB84 is not shown to be insecure.

    Why

    QKD security statements rest on long analytic arguments that are rarely independently rechecked, so a mechanised proof that surfaces gaps is the kind of scrutiny the field has lacked. It does not change what BB84 hardware does; implementation side channels are outside its scope. Whether the missing branch changes any published key-rate bound is not in the abstract, and I did not read the paper.

Music Practice

2

  1. 01

    Trumpet: Arban first studies for an even tone, then one melody to sing

    [2026-10-25] · src —

    • trumpet
    • assignment

    Trumpet takes today: three days since it was last assigned, the longest gap of the three, and it wants a short session. Last time was Syncopation, so today goes back to the First Studies in Arban, whose job is tone and evenness, paired with a melody from the Art of Phrasing. The aim is notes that are the same size and shape from one to the next, in the middle register.

    Warmup

    5 minutes: long tones on written C (third space) down by half steps to written F# below the staff, mp, 8 beats each, easy attack and a breath between. Then 2 minutes of lip slurs on C-G-C at mf, slowly.

    Technical target

    Choose one First Studies exercise in a comfortable key and play it slurred, then tongued, at quarter = 60, 72, then 84. Success criterion: three consecutive passes at each tempo where every note has the same weight and the tongued pass sounds as smooth as the slurred one.

    Musical target

    Play one melody from the Art of Phrasing, a different number than on 10-22. Mark the peak of each phrase, play toward it, and let the end of the phrase settle without going flat or sharp. It should sound like one breath per phrase.

    Stop condition

    About 25 minutes, and stop sooner if the tone spreads or the lips buzz rather than ring. A short session that ends while the sound is still good beats a long one that ends ragged; do not add a second block.

  2. 02

    Listening: Clifford Brown and Max Roach, "Daahoud"

    [2026-10-25] · src —

    • trumpet
    • listening

    hearClifford Brown and Max Roach — Daahoud · Tidal · Spotify

    Brown's own tune, a brisk bebop line. Listen to how every note in a fast run has the same weight and the same clean edge, so that tonguing never interrupts the sound. That is the evenness the First Studies are meant to build, at a tempo well above today's.