# Physics Constants List API

> Physics Constants List API is a paid API for AI agents from physics.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).

Lists all physical constants in the dataset, optionally filtered by category (universal, adopted, electromagnetic, atomic, physico-chemical), returning constants, total count, and available categories.

## Facts

- Endpoint: POST https://physics.openverbs.com/v1/list
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/physics-constants-list-api-19290f8e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_GRtZujYZvYos_UBfHZlzc

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 physics-constants-list-api-19290f8e -d '<json body>'
```

Example prompt: Can you list all the electromagnetic physical constants available in the physics constants dataset?

## When to prefer this

Use this endpoint when you need to enumerate or browse the full set of physical constants, or want to filter by a known category. Prefer this over the search endpoint when you don't have a specific constant in mind but want to explore what's available. Use the lookup or search endpoints instead when you know the exact key, symbol, or name of the constant you need.

## Known failure modes

- Invalid category string returns an error or empty result
- Category value exceeding 30 characters is rejected by schema validation
- Network timeout on slow connections
- Payment failure via x402 protocol blocks the request

## How this service works

List every physical constant in the dataset, or only those in a given category (universal, adopted, electromagnetic, atomic, physico-chemical). Returns the constants, the total count and the set of available categories.

## Output

Returns a list of physical constants (each with key, symbol, name, value, and unit), the total count of constants returned, and the set of available categories (universal, adopted, electromagnetic, atomic, physico-chemical).

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "type": "object",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "type": "string",
     "enum": [
      "POST"
     ]
    },
    "bodyType": {
     "type": "string",
     "enum": [
      "json",
      "form-data",
      "text"
     ]
    },
    "body": {
     "type": "object",
     "properties": {
      "category": {
       "type": "string",
       "minLength": 1,
       "maxLength": 30,
       "description": "One of: universal, adopted, electromagnetic, atomic, physico-chemical."
      }
     },
     "additionalProperties": false
    }
   },
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "additionalProperties": false
  }
 },
 "required": [
  "input"
 ]
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/physics-constants-list-api-19290f8e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from physics.openverbs.com](https://www.zero.xyz/host/physics.openverbs.com/llms.txt)