Did Dark Matter Begin Massless? 

SCIENCE

By Aniket Chakraborty May 22, 2025 Arrow

A new Dartmouth study suggests it was once fast, hot, and massless—like photons.

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Over time, these particles collided, cooled, and suddenly gained mass.

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Researchers say this shift could explain today’s “cold, lumpy” dark matter.

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The theory proposes a dramatic energy drop triggered this transformation.

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“Our idea is testable using the Cosmic Microwave Background,” says Prof. Caldwell.

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The CMB holds radiation from the Big Bang—dark matter may have left a trace.

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Opposing particle spins, like magnetic poles, may have caused the bonding.

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This model also hints at a never-before-seen particle that sparked the change.

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If true, this theory could reshape how we understand the invisible matter binding the cosmos.

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