Instant · Precise · Universal
32 units available
6 categories total
To convert to meters: multiply by 2.8179403262 × 10⁻¹⁵.
re = e²/(4πε₀mec²) ≈ 2.8179 × 10⁻¹⁵ m, where e is electron charge and me is electron mass.
For example, 1 Electron Radius (Classical) (re) = 2.978575e-31 Light Year (ly).
| Electron Radius (Classical) (re) | Light Year (ly) |
|---|---|
| 0.1 | 2.978575e-32 |
| 0.5 | 1.489287e-31 |
| 1 | 2.978575e-31 |
| 2 | 5.957150e-31 |
| 5 | 1.489287e-30 |
| 10 | 2.978575e-30 |
| 25 | 7.446437e-30 |
| 50 | 1.489287e-29 |
| 100 | 2.978575e-29 |
| 500 | 1.489287e-28 |
| 1000 | 2.978575e-28 |
The classical electron radius is a theoretical length scale derived from the electron's charge and mass, approximately 2.818 × 10⁻¹⁵ meters.
re = e²/(4πε₀mec²) ≈ 2.8179 × 10⁻¹⁵ m, where e is electron charge and me is electron mass.
To convert to meters: multiply by 2.8179403262 × 10⁻¹⁵.
Used in calculating X-ray and gamma-ray scattering probabilities off electrons (Thomson and Compton scattering).
Despite its name, the electron is a point particle in quantum theory — the 'classical radius' is a theoretical construct, not the electron's actual size.
Assuming this is the actual physical size of the electron — quantum mechanics shows the electron has no measurable size.
Think of it as the scale at which classical electromagnetic self-energy equals the electron's mass-energy.
The light-year is the distance that light travels in one Julian year (365.25 days) in a vacuum, approximately 9.461 × 10¹⁵ meters.
1 ly = 9.4607 × 10¹⁵ m = 63,241 AU = 0.3066 pc ≈ 9.461 trillion km.
To convert ly to km: multiply by 9.461 × 10¹². To convert ly to parsecs: multiply by 0.3066.
Expressing distances to stars: Proxima Centauri ≈ 4.24 ly, Sirius ≈ 8.6 ly, Vega ≈ 25 ly.
When you see a star 100 light-years away, you're seeing it as it was 100 years ago — you're literally looking into the past.
Thinking a light-year is a unit of time — it's a unit of distance! It's how far light travels in one year.
Light speed = ~300,000 km/s. In one year, light covers ~9.46 trillion km. That distance is one light-year.



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