Alex McColgan

speaker

27,837 appearances 101 recordings 1 series first heard Nov 2024 last heard 5d ago

Alex McColgan’s voice in public audio — every appearance, attributed to the second.

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recordings per month · last 12 months

Recordings per month over the last 12 months — 65 in all, peaking in Aug 2026 with 11.

Appearances

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Astrum Space · We Thought It Was Impossible, But We’ve Finally Seen It · 31 Aug 2026 podcast

to an accuracy level of better than a few percent. voice-verified

That gives us a precise budget for how many atoms should be in the universe today. voice-verified

But just because it's made of stuff that's visible to us doesn't mean it's easy to see. voice-verified

When astronomers go out and count up all the stars, gas, dust and plasma we can see, with the help of models and simulations, we only find about sixty percent of what should be there. voice-verified

The rest has to exist for early universe physics to make sense, but voice-verified

But unless we can find it, we can't prove that our models are right. voice-verified

Maybe we've got it all wrong. voice-verified

Thankfully, scientists haven't been that quick to give up. voice-verified

and instead turn their attention to working out where the missing mass may be lurking. voice-verified

And they came up with an intriguing hypothesis. voice-verified

Missing baryonic matter is not the only missing mass, and perhaps they're hiding together. voice-verified

Nearly a century ago, Swiss-born astronomer Fritz Zwicky noticed that galaxies in the coma cluster moved too quickly for the amount of gravity that would be created by their visible matter alone. voice-verified

Yes, including the missing stuff. voice-verified

Instead, he thought another form of mass must be there, and in nineteen thirty three, Zwicky dubbed this missing substance dunkel materi. voice-verified

The German for Dark Matter. voice-verified

In the nineteen seventies, American astronomer Vera Rubin had a similar experience. voice-verified

She was observing spiral galaxies and wondered how stars on the outer edge of the spiral galaxies were able to move so quickly without flying off into space. voice-verified

Again, some unknown mass must have been pulling them back in. voice-verified

And she concluded the same as Tsvicki. voice-verified

There must be dark matter holding them together. voice-verified

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