# Sindri Physical Constants Lookup

> Sindri Physical Constants Lookup is a paid API for AI agents from x402.outpimp.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Returns the exact CODATA-published value of a named fundamental physical constant (e.g. speed of light, Planck constant, Boltzmann constant).

## Facts

- Endpoint: POST https://x402.outpimp.com/physicalConstants
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sindri-physical-constants-lookup-9a3b5201
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_G6mDFzmGzZC_vtGYZp3hs

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sindri-physical-constants-lookup-9a3b5201 -d '<json body>'
```

Example prompt: What is the exact CODATA value of the Boltzmann constant? Look it up using the physicalConstants endpoint with 'boltzmannConstant'.

## When to prefer this

Use this endpoint when you need a precise, authoritative CODATA value for one of the eight supported fundamental physical constants and want a deterministic, reproducible lookup rather than relying on a language model's potentially imprecise recall. Ideal for scientific computing, formula verification, or educational tools.

## Known failure modes

- Invalid or unsupported constant name — only the eight enumerated constants are accepted
- Missing 'constant' field in request body returns validation error
- Network timeout or service unavailability returns HTTP error

## How this service works

Lookup of standard physical constants (speed of light, gravitational constant, Planck constant, elementary charge, Avogadro number, Boltzmann constant, gas constant, electron mass) with exact published CODATA values.

## Output

Returns the exact CODATA-published numeric value (and likely units) for the requested physical constant — one of: speedOfLight, gravitationalConstant, planckConstant, elementaryCharge, avogadroNumber, boltzmannConstant, gasConstant, or electronMass.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "constant": {
   "enum": [
    "speedOfLight",
    "gravitationalConstant",
    "planckConstant",
    "elementaryCharge",
    "avogadroNumber",
    "boltzmannConstant",
    "gasConstant",
    "electronMass"
   ],
   "type": "string",
   "description": "Which constant to look up."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sindri-physical-constants-lookup-9a3b5201/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.outpimp.com](https://www.zero.xyz/host/x402.outpimp.com/llms.txt)