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Why do scientists assume that without liquid water, a planet cannot have life? Why can’t aliens function off a different substance, why must it be water?

Mark Sterling
Mark Sterling
Research Editor · Feb 18, 2026 · Updated Apr 13, 2026

More about likelihood, then absolutes. Of course a planet without liquid water could sustain life, but in our experience, only planets that have life, to our knowledge, are those with liquid water, to which life is dependant.

37
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1 min
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#356
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The Short Answer

More about likelihood, then absolutes. Of course a planet without liquid water could sustain life, but in our experience, only planets that have life, to our knowledge, are those with liquid water, to which life is dependant.

Analysis

Key Concepts: Life, liquid, water

This explanation focuses on life, liquid, water and spans 37 words across 2 sentences. At 43% below the average Everyday Life explanation (65 words), the answer takes a direct, no-frills approach — sometimes the simplest explanation is the most effective.

What This Answer Covers

This is a focused, single-point answer that gets directly to the core of the question without detours.

How This Compares in Everyday Life

Ranked #356 of 500 Everyday Life questions by answer depth (top 72%). This is in the concise tier — a focused explanation that prioritizes clarity over exhaustiveness. Many readers prefer this level of directness.

Frequently Asked Questions

Is there a simple explanation for why scientists assume that without liquid water, a planet cannot have life? why can't aliens function off a different substance, why must it be water?

More about likelihood, then absolutes. Of course a planet without liquid water could sustain life, but in our experience, only planets that have life, to our knowledge, are those with liquid water, to which life is dependant.

How detailed is this explanation compared to similar Everyday Life questions?

This is a focused answer at 37 words, ranked #356 of 500 Everyday Life questions by depth. The key concepts covered are life, liquid, water.

What approach does this answer take to explain scientists assume that without liquid water, a planet cannot?

The explanation uses contrasting perspectives across 37 words. It is categorized under Everyday Life and addresses the question through 1 analytical lens.