Half Life

{
  "asOf": "2026-10-11T08:45:39.195Z",
  "decayConstantPerUnit": 0.00012096809,
  "decayedAmount": 75,
  "decayedPercent": 75,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "elapsed": 11460,
  "halfLife": 5730,
  "halfLivesElapsed": 2,
  "isotope": "carbon-14 (half-life 5730 years)",
  "meanLife": 8266.6426,
  "notChecked": [
    "measurement uncertainty and the age calibration needed for real radiocarbon dating (atmospheric C-14 varied over time)",
    "decay chains and daughters that are also radioactive",
    "…2 more"
  ],
  "reasons": [
    "Remaining fraction = (1/2)^(time / half-life); time = half-life x log2(1 / fraction). Mean life = half-life / ln 2.",
    "After 10 half-lives about 0.0977% remains."
  ],
  "remainingAmount": 25,
  "remainingFraction": 0.25,
  "remainingPercent": 25,
  "source": "computed locally",
  "summary": "carbon-14 (half-life 5730 years): after 11460 years (2 half-lives) 25% remains (25 of 100); decay constant 0.00012097 per unit, mean life 8266.64.",
  "unit": "years",
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://chemistry-calc.x402tookit.com/half-life?elapsed=11460&initial=100&isotope=c-14'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://chemistry-calc.x402tookit.com/half-life?elapsed=11460&initial=100&isotope=c-14' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fchemistry-calc.x402tookit.com%2Fhalf-life
const res = await pay("https://chemistry-calc.x402tookit.com/half-life?elapsed=11460&initial=100&isotope=c-14");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://chemistry-calc.x402tookit.com/half-life?elapsed=11460&initial=100&isotope=c-14")
    print(res.status_code, res.text)