Light going 30X faster than c? Whats up?

https://phys.org/news/2019-04-researchers-develop-way-to-control.html

It says they made the light go 30X faster, WTF? Is that just another phase velocity thing?

@sonhouse said
https://phys.org/news/2019-04-researchers-develop-way-to-control.html

It says they made the light go 30X faster, WTF? Is that just another phase velocity thing?

Wut?

Your OP link says;

"...Abouraddy and study co-author Esat Kondakci demonstrated they could speed a pulse of light up to 30 times the speed of light..."

which sounds like nonsense because that's impossible. If they DID do such a thing it would be huge news and on every front page. But perhaps they were misquoted? Or perhaps that was a missedit? Or perhaps what they exactly meant isn't as indicated by their exact words there?

@humy

The original paper is downloadable for free from Nature's website, the link is in the phys.org article. They are talking about group velocity and specify, in the abstract that this is not in contradiction with relativity as information cannot be transferred this way. This is in free space using carefully shaped wave packets.

I need to do a little revision before commenting further as I was under the impression that group velocity did specify the speed of propagation of energy and information.