Space & Astronomy

Our galaxy may be sitting inside a cosmic void, scientists suggest

By T.K. Randall
July 8, 2025 ·  3 comments

Image: The Scale of the Universe
Credit: ESA/Hubble/D. Calzetti et al. / CC BY 4.0 (adapted) The accelerating expansion of the universe remains one of the most hotly debated topics in all of physics - especially with regard to exactly how fast that expansion is happening.

Different methods for measuring this - such as by tracking the motion of nearby galaxies or by using the cosmic microwave background radiation - seem to produce different results.

But what if the answer to this discrepancy happens to lie much closer to home than we realize ?

Now new research has proposed that the reason why these different methods for measuring the rate of expansion don't add up is because our galaxy is sitting within a large cosmic void - a vast region of space in which there is very little relative to most of the rest of the universe.If this happened to be true, then we might expect to see increased acceleration in our local area (cosmically speaking) due to the surrounding galaxies tugging at our own galaxy.

"It would cause matter to be pulled by gravity towards the higher density exterior of the void, leading to the void becoming emptier with time," Dr Indranil Banik from the University of Portsmouth told IFLScience.

"As the void is emptying out, the velocity of objects away from us would be larger than if the void were not there. This, therefore, gives the appearance of a faster local expansion rate."

Also, if this happened to be the case, there are other aspects of our current model of the universe that might also need to be changed to account for this phenomenon.

As things stand, however, most scientists tend to favor other explanations.

Source: IFL Science | Comments (3)

Tags: Galaxy