Archive for October 17, 2019

Ten Years on Twitter

Posted in Biographical with tags , on October 17, 2019 by telescoper

This morning, a certain social media site pointed out to me that it is ten years to the day since I started using it.

My experiences of Twitter haven’t been anything like as bad as some people I know have reported. I think that’s probably because I’m quite liberal with the ‘block’ facility when it comes to bots and trolls and sundry other tediously offensive types. I have found that the positives have definitely outweighed the negatives over the last decade, and I count myself lucky to have encountered some very lovely people on Twitter, some of whom I have eventually met in the real world.

I don’t have a huge following on Twitter, but I’d like to take this opportunity to say that I do appreciate those who do read my tweets and hope that they find at least some of them interesting or amusing!

Gravitational Lensing, Cosmological Distances and the Hubble Constant

Posted in The Universe and Stuff with tags , , , on October 17, 2019 by telescoper

To continue the ongoing Hubble constant theme, there is an interesting paper on the arXiv by Shajib et al. about determining a distance to a gravitational lens system; I grabbed the above pretty picture from the paper.

The abstract is:

 

You can click on this to make it bigger. You will see that this approach gives a `high’ value of H0 ≈ 74.2, consistent with local stellar distances measures, rather than with the `cosmological’ value which comes in around H0 ≈ 67 or so. It’s also consistent with the value derived from other gravitational lens studies discussed here.

Here’s my ongoing poll on the Hubble constant, with