Letter: Universe's radius

From Gareth Lloyd

I write further to Patrick Johnson’s letter (16 April, p 29) that questioned the accepted idea in your feature covering the “horizon problem” that the radius of the observable universe is about 14 billion light years (19 March, p 30).

Charles Lineweaver and Tamara Davis, astronomers from Mount Stromlo Observatory near Canberra, Australia, support Johnson’s view and in March contended that the expansion of space itself means that the most distant objects we can see are actually about 74 billion kilometres distant.

It may be true to say that an ancient galaxy may now be at that distance, but does this mean we can “see” that far? Not in my opinion. What we are actually seeing is not the galaxy as it is (it may even no longer exist), but as it was when it was 14 billion light years away.

I think, therefore, that this new idea for regarding the width of the observable universe as much extended is in error.

Lindfield, West Sussex, UK