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Columnist and Space

How the balloon analogy for an expanding universe is almost perfect

If space-time is expanding, then why does gravity seem to pull things together? Physics can be weird, says Chanda Prescod-Weinstein

By Chanda Prescod-Weinstein

11 October 2023

S3F98G Colorful balloons against the light

Irena Sowinska/Stockimo/Alamy

MOST people have probably heard that the universe is expanding. Certainly New Scientist readers have, because I keep writing about it in this column. It is perhaps easy to accept the statement that the universe is expanding without thinking too deeply about it. It is just some weird physics indicating that, as time goes on, galaxies get further away from each other. Or maybe you have heard the old race car analogy, that galaxies moving apart are like two cars racing away from each other.

I personally detest the race car analogy and prefer the balloon with slightly magical…

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