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Radiation Density Redshift Quartic Term Tool

Freely redshifting radiation density scales as (1+z)^4.

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Description

Scale a supplied radiation energy density with redshift.

Cosmological redshift relates emitted and observed scales through a declared normalization. Density components, lengths and temperatures follow different model-dependent powers of the expansion factor, so matching symbols or dimensions does not make their physical meanings interchangeable.

Scale a supplied radiation energy density with redshift.

When to use this tool

Use Radiation Density Redshift Quartic Term when evaluating the stated redshift scaling under its explicit normalization and component assumptions.

How to use the tool and how it works

  1. Enter presentDensity, redshift. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read densityFactor, density. Use the output convention below.

Scale a supplied radiation energy density with redshift. Require presentDensity >= 0 and z > -1; densityFactor = (1+z)^4, density = presentDensity*factor.1

Input fieldMeaning and unitsAccepted input
presentDensityPresent DensityRequired. Finite number; minimum 0.
redshiftDimensionless redshift z; the stated scaling formulas require z > -1.Required. Finite number; strictly above -1.
Output fieldInterpretationReturned shape
densityFactorDensity FactorRequired. Finite number.
densityDensity on the same physical and unit basis as the supplied reference or component; see the formula above.Required. Finite number.
json
{
  "input": {
    "presentDensity": 2,
    "redshift": 1
  },
  "output": {
    "densityFactor": 16,
    "density": 32
  }
}

Limitations and assumptions

  • This assumes the standard freely redshifting radiation scaling; no species transitions or cosmological parameter fit is performed.
  • Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
  • Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use a complete cosmological model with justified parameters for expansion histories, component evolution and observational inference.

References

  1. Calculation and input contract: cosmology/radiation-density-redshift-quartic-term — tool.io

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