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Why does light have speed? Why isn’t it instantaneous?

Mark Sterling
Mark Sterling
Research Editor · Mar 20, 2026 · Updated Apr 13, 2026

Light is still an electromagnetic wave and takes time to propagate through space. It is more technically accurate to think of c as the universal speed limit and just know that lights *happens* to travel at c. If you assume c to be infinite, you get Newtonian physics.

67
Words

1 min
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#233
of 500 in Science

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vs Category Avg

The Short Answer

Light is still an electromagnetic wave and takes time to propagate through space. It is more technically accurate to think of c as the universal speed limit and just know that lights *happens* to travel at c. If you assume c to be infinite, you get Newtonian physics. Because Einstein recognized that all inertial reference frames view c identically, it redefined our coordinates for mapping the universe.

Analysis

Key Concepts: Light, electromagnetic, wave

This explanation focuses on light, electromagnetic, wave and spans 67 words across 4 sentences. The depth is typical for Science questions (category average: 72 words), striking a balance between accessibility and completeness.

What This Answer Covers

The explanation opens with: “Light is still an electromagnetic wave and takes time to propagate through space.” It then elaborates by explaining the root cause, ultimately building toward a complete picture across 4 connected points.

How This Compares in Science

Ranked #233 of 500 Science questions by answer depth (top 47%). This falls in the detailed tier — above average depth. The explanation goes beyond surface-level but keeps things accessible.

Frequently Asked Questions

Is there a simple explanation for why light have speed? why isn't it instantaneous?

Light is still an electromagnetic wave and takes time to propagate through space. It is more technically accurate to think of c as the universal speed limit and just know that lights *happens* to travel at c. If you assume c to be infinite, you get…

How detailed is this explanation compared to similar Science questions?

This is an above-average answer at 67 words, ranked #233 of 500 Science questions by depth. The key concepts covered are light, electromagnetic, wave.

What approach does this answer take to explain light have speed? why isn't it instantaneous?

The explanation uses root cause analysis across 67 words. It is categorized under Science and addresses the question through 1 analytical lens.