Openai/692c92ef-d2d4-8004-94ad-873bcf71e84f

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gpt-5-1

User: How much mass is in the universe?

How much mass is in the universe?

Assistant: Estimating the total mass of the universe depends on what you include—normal matter, dark matter, dark energy—and wheth…

Estimating the total mass of the universe depends on what you include—normal matter, dark matter, dark energy—and whether you mean the observable universe or the entire (possibly infinite) universe.

Below is the standard, physics-based answer.

⭐ Mass in the Observable Universe

Cosmology gives us precise estimates for the observable universe using measurements of density from the cosmic microwave background (Planck mission).

1. Critical density

The universe’s average mass–energy density (critical density):

ρc≈9.2×10−27 kg/m3\rho_c \approx 9.2 \times 10^{-27}\ \text{kg/m}^3ρc​≈9.2×10−27 kg/m3 Volume of the observable universe:

V≈3.6×1080 m3V \approx 3.6 \times 10^{80}\ \text{m}^3V≈3.6×1080 m3

⭐ Breakdown by component

Ordinary (baryonic) matter – ~5%

Mbaryonic≈1.5×1053 kgM_{\text{baryonic}} \approx 1.5 \times 10^{53}\ \text{kg}Mbaryonic​≈1.5×1053 kg

Dark matter – ~27%

Mdark matter≈8×1053 kgM_{\text{dark matter}} \approx 8 \times 10^{53}\ \text{kg}Mdark matter​≈8×1053 kg

Total mass (matter only)

Mtotal matter≈1×1054 kgM_{\text{total matter}} \approx 1 \times 10^{54}\ \text{kg}Mtotal matter​≈1×1054 kg

⭐ If you include dark energy

Dark energy isn’t “mass” in the usual particle sense, but it contributes most of the universe’s energy density (~68%). If you convert that energy density into an equivalent mass via E=mc2E = mc^2E=mc2:

Mdark energy (equiv.)≈3×1054 kgM_{\text{dark energy (equiv.)}} \approx 3 \times 10^{54}\ \text{kg}Mdark energy (equiv.)​≈3×1054 kg

🔵 Grand Total (mass-energy equivalent)

Muniverse≈4×1054 kgM_{\text{universe}} \approx 4 \times 10^{54}\ \text{kg}Muniverse​≈4×1054 kg This is the best estimate for the entire observable universe.

⭐ What about the whole universe?

Most cosmological models imply the universe is:

• spatially flat
• much larger than the observable part
• possibly infinite

If the universe is infinite, then the total mass is infinite. If it's finite but unbounded (like a 3-sphere), it would be some multiple of the observable value, but we do not know the factor.

Summary

| Component | Mass in Observable Universe | | -------------------- | --------------------------- | | Ordinary matter | ~ 1.5 × 10 53 1.5×10 53

kg |

| Dark matter | ~ 8 × 10 53 8×10 53

kg     |

| Dark energy (equiv.) | ~ 3 × 10 54 3×10 54

kg     |

| Total | ~ 4 × 10 54 4×10 54

kg     |

If you'd like, I can also convert that into solar masses, earth masses, or compare it to the number of atoms.