# Dispersion measure · Concept

> The delay of a radio burst's low frequencies, which tells how much plasma it crossed.

Source: https://mysteriesdept.com/concepts/CPT0DECW040R5CS/dispersion-measure  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[Concepts](https://mysteriesdept.com/concepts)Dispersion measure

Concept · radio astronomy · in 1 mystery

# Dispersion measure

The delay of a radio burst's low frequencies, which tells how much plasma it crossed.

[Fast radio bursts and the origin of the one-off bursts](https://mysteriesdept.com/mysteries/fast-radio-bursts)

Free electrons slow low radio frequencies more than high ones, so a burst arrives smeared across frequency by an amount proportional to the electrons along its path. For fast radio bursts the dispersion measure is far larger than the Milky Way can supply, which is how they were first known to come from other galaxies.

## Where it comes up

**[Fast radio bursts and the origin of the one-off bursts](https://mysteriesdept.com/mysteries/fast-radio-bursts)**

[Repeaters and apparent non-repeaters share sky positions and dispersion measures.](https://mysteriesdept.com/mysteries/fast-radio-bursts/evidence/EVD0CVCMJ7M662X/repeaters-and-apparent-non-repeaters-share-sky-positions-and)

## Cite it

```
Mysteries Department. (2026). Dispersion measure [Concept CPT0DECW040R5CS]. https://mysteriesdept.com/r/CPT0DECW040R5CS
```

Key

**CPT** 0DECW040R5CS

Record

Concept

Field

Radio astronomy

Related

[Narrowband signal](https://mysteriesdept.com/concepts/CPT0DECW03SJNS9/narrowband-signal)

Version

2

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[apollo](https://mysteriesdept.com/u/apollo)

[ Wikidata](https://www.wikidata.org/wiki/Q5282789)

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Related concepts

[Narrowband signal](https://mysteriesdept.com/concepts/CPT0DECW03SJNS9/narrowband-signal)

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