The physics of devices: quantum, semiconductors, electronics, photonics.Figures checked 1 Nov 2026

The physics of devices, with the numbers.

How matter, charge and light behave at the scale of a device: the definitions that are right, the figures with their sources, and the calculators that give the number.

Quantum physics

How states, measurement and entanglement work at the smallest scales, from Planck's constant to working qubits.

21 articlesStart here

Semiconductors

What happens to charge inside a crystal: carriers, band gap, junctions, transistors and the silicon that detects particles.

16 articles, 3 calculatorsStart here

Electronics

Devices built, measured and chosen: image sensors, memory, chips, thermal and energy limits, with the datasheet numbers.

11 articlesStart here

Photonics

Light as carrier and probe: optical fibre, silicon photonics, photodetectors, and how photons interact with matter.

11 articles, 1 calculatorStart here

One energy window, four subjects. The quantities these pages compute, on a single scale from the thermal energy of a transistor to the ionisation of hydrogen.

CODATA 2018, materials library

Instruments

Ten calculators, free, one answer at a time. Every result prints its source and a citation.

Semiconductors 3 live

Energy-loss calculator

Particle, material and thickness in; mean loss, most probable value and straggling out.

Bethe and Landau Materials library

Search and compare density, excitation energy and radiation properties for 17 materials.

PDG and NIST Detector signal calculator

Electron-hole pairs and fully collected charge in silicon and germanium.

PDG; NIST ESTAR

First planned: Intrinsic carrier density and band gap against temperatureSi, Ge, GaAs, SiC, GaN

Photonics 1 live

Photon attenuation calculator

Half-value layer and transmission for gamma and X-ray beams through common materials.

NIST XCOM

First planned: Fibre link budget and attenuationITU-T G.652, G.657

Radiation 6 live

Radioactive decay calculator

Calculate decay and daughter activity.

NNDC NuDat 3 Accelerator power and synchrotron loss calculator

Calculate dipole radiation for one beam in an isomagnetic ring.

CODATA 2018; Sands SLAC-121 Gamma dose rate calculator

Calculate air kerma from an isotropic point gamma source: K̇ = Γδ A / d², with optional shielding.

NNDC; NIST; LNHB

Quantum physics planned

First planned: Photon energy, wavelength and frequency converterCODATA 2018

Electronics planned

First planned: MOSFET long-channel current and thresholdSze, Tsividis

Also in Radiation: Cosmic radiation and flight dose calculator, X-ray tube spectrum and filtration calculator, Radiation units converter. All ten instruments

Start here

The first article of each pillar’s reading path. Each path goes from the first concept to the current state of the field in five or six pieces.

Quantum physicsMax Planck’s Impact on the Birth of Quantum PhysicsMax Planck didn't set out to break physics -- his 1900 fix for the blackbody radiation problem introduced the quantum and he spent years doubting it.SemiconductorsCharge Carriers in Semiconductors: Electrons, Holes and Pair CreationCharge carriers in semiconductors are electrons and holes. See how a 1.12 eV band gap in silicon creates them and why a particle needs about 3.6 eV per pair.ElectronicsHow does a CCD sensor work? A pixel’s charge can travel 4,096 steps before it is readYour phone reads each pixel where it sits. A CCD passes every pixel's charge, step by step, to an amplifier at the edge of the chip.PhotonicsAre Photons Matter? The Answer Has an Error BarAre photons matter? No — but "massless" is a measured bound, not an assumption, and the number keeps moving by orders of magnitude.

Latest

Across the four pillars, newest first.

30 Oct 2026ElectronicsHow does a CCD sensor work? A pixel’s charge can travel 4,096 steps before it is readYour phone reads each pixel where it sits. A CCD passes every pixel's charge, step by step, to an amplifier at the edge of the chip.27 Oct 2026ElectronicsAn H100 operation costs about 100 million Landauer limitsPhysics sets a floor for erasing one bit. At peak, an H100 spends about 100 million times that energy per operation: a scale, not a like-for-like test.13 Oct 2026PhotonicsWhy data in optical fibre is 32% slower than lightData in fibre is often said to move at the speed of light. In standard fibre it moves at 204,107 km/s, 68.1% of it, because the glass slows the pulse.3 Oct 2026ElectronicsCosmic Rays and Silent Data Corruption in Data CentresCosmic-ray neutrons are real, but field studies point to hardware defects behind most DRAM faults and the silent core errors operators have traced.29 Aug 2026SemiconductorsMoS2 Radio Survives Nine Months in Orbit: What It ShowsA 2026 orbital MoS2 radio experiment ran for nine months. Its measured error rate supports a promising result, with mission qualification still ahead.22 Aug 2026Quantum physicsQuantum Error Correction Threshold Theorem: Why Scale HelpsQuantum error correction threshold theorem: why Google's Willow gets more reliable as it scales, while near-threshold chips don't.15 Aug 2026ElectronicsIntel Glass Core Substrate: Why It’s Not ShippingIntel's glass core substrate is not in Clearwater Forest, which uses organic substrate and EMIB. What ECTC 2026 showed, and why glass is years away.8 Aug 2026Quantum physicsOne-Dimensional Anyons: Breaking Statistics Without BraidingOne-dimensional anyons ditch braiding entirely — cold-atom experiments show head-on collisions alone tune quantum statistics continuously.28 Jul 2026Quantum physicsMagnon Qubit Quantum Computing: Wrong Job Title?Magnon qubit quantum computing headlines miss the point: real experiments show magnons acting as quantum memory, not stand-alone qubits.25 Jul 2026Electronics3D Chip Stacking’s Thermal Limit Splits Cache From Cores3D chip stacking's thermal limit lets cache stack almost free, but logic-on-logic still cooks itself — a split that won't close for years.15 Jul 2026ElectronicsData Center SSD Shortage 2026: Why NAND Lost to DRAMThe 2026 NAND and SSD shortage comes from fabs moving lines to DRAM and HBM. NAND contract prices rise 15 to 20% in 4Q26; plan for tight supply into 2027.12 Jul 2026PhotonicsSiPM vs PMT: Why Silicon Hasn’t Won Everywhere YetSiPM vs PMT: silicon wins on efficiency, voltage and magnetic immunity, but tubes still win on collecting area per euro. The numbers and a verdict.