De mora luminis: Roemer's discovery 350 years later

15 hours ago

350 years after Roemer's 1676 announcement, the authors used telescopes with resolution similar to late 17th-century instruments to confirm his method for measuring the speed of light.
Roemer's method yields values for c within about 10% of the modern value, even with a simple model of uniform circular motion.
Increasing model complexity (e.g., including Jupiter's elliptical orbit) does not always improve accuracy due to other perturbations.
Using modern ephemerides gives a precise result of c = (298200 ± 1900) km/s.
This experience has didactic value, showing the interplay between hypothesis formulation, predictions, observations, data reduction, and exploring alternative explanations.
In 1677 correspondence with Huygens, Roemer sought independent confirmation of his findings by observing Jupiter's Great Red Spot meridian transits.

The author uses a Navilock NL-8012U with a u-blox 8 chipset, configuring it via u-center to enable Galileo and NMEA 4.1 for raw data.
Galileo ephemeris parameters in semi-circle units require multiplication by π for calculations.
Eccentric anomaly is computed through iteration (E = M + e * sin(E)), often in 10 iterations.

The universe's expansion is accelerating due to dark energy, a discovery that won the Nobel Prize in 2011.
The Hubble tension arises from a significant discrepancy between local measurements of the expansion rate (using supernovae) and predictions from the cosmic microwave background based on the Lambda-CDM model.
The Lambda-CDM standard model is highly successful but may have cracks, as multiple independent measurements consistently show a mismatch.

In 2010, a 36-minute observation using an experimental polarimeter (ExPo) revealed vast concentric rings encircling Venus's day side, visible only in polarized light.
Researchers spent years trying to prove the observation was an instrument error, but the signal persisted through all tests.
Computer simulations showed that atmospheric gravity waves causing density variations of 5–10% could produce the polarization rings.

Schema harness enables frontier models to achieve ~99% performance on ARC-AGI-3 Public by treating latent world representations as executable programs, allowing interpretable, verifiable, and searchable modeling.
ARC-AGI-3 challenges agents to infer game rules, objects, and goals from raw 64x64 color grids without explicit instructions, using the Relative Human Action Efficiency (RHAE) metric for evaluation.
The approach combines state grounding (identifying objects and variables from observations) and mechanism discovery (learning transition rules), solved jointly within an editable program that mirrors physicist-like reasoning.

Trammell H designed a geocentric orrery with Earth at the center to easily identify planets in the sky, featuring daily Sun rotation and Moon lag of 12.19°.
The model is mostly 3D printed using FreeCad, with sources on GitHub, and includes a timelapse on Mastodon showcasing its alignment with actual azimuths.
He is preparing a writeup on epicyclic gear math and integer gear teeth combinations to achieve accurate synodic period ratios, minimizing error except for Jupiter requiring occasional adjustments.

The author uses a Navilock NL-8012U with a u-blox 8 chipset, configuring it via u-center to enable Galileo and NMEA 4.1 for raw data.
Galileo ephemeris parameters in semi-circle units require multiplication by π for calculations.
Eccentric anomaly is computed through iteration (E = M + e * sin(E)), often in 10 iterations.

The universe's expansion is accelerating due to dark energy, a discovery that won the Nobel Prize in 2011.
The Hubble tension arises from a significant discrepancy between local measurements of the expansion rate (using supernovae) and predictions from the cosmic microwave background based on the Lambda-CDM model.
The Lambda-CDM standard model is highly successful but may have cracks, as multiple independent measurements consistently show a mismatch.

In 2010, a 36-minute observation using an experimental polarimeter (ExPo) revealed vast concentric rings encircling Venus's day side, visible only in polarized light.
Researchers spent years trying to prove the observation was an instrument error, but the signal persisted through all tests.
Computer simulations showed that atmospheric gravity waves causing density variations of 5–10% could produce the polarization rings.

Schema harness enables frontier models to achieve ~99% performance on ARC-AGI-3 Public by treating latent world representations as executable programs, allowing interpretable, verifiable, and searchable modeling.
ARC-AGI-3 challenges agents to infer game rules, objects, and goals from raw 64x64 color grids without explicit instructions, using the Relative Human Action Efficiency (RHAE) metric for evaluation.
The approach combines state grounding (identifying objects and variables from observations) and mechanism discovery (learning transition rules), solved jointly within an editable program that mirrors physicist-like reasoning.

Trammell H designed a geocentric orrery with Earth at the center to easily identify planets in the sky, featuring daily Sun rotation and Moon lag of 12.19°.
The model is mostly 3D printed using FreeCad, with sources on GitHub, and includes a timelapse on Mastodon showcasing its alignment with actual azimuths.
He is preparing a writeup on epicyclic gear math and integer gear teeth combinations to achieve accurate synodic period ratios, minimizing error except for Jupiter requiring occasional adjustments.

Hasty Briefsbeta