Einstein fights back

[sjastro]

Despite those pesky neutrinos.....

http://www.nbi.ku.dk/english/news/ne...f_relativity_/

Regards

Steven

[renormalised (Carl)]

This is not so much a case of "Einstein Strikes Back" as it's a case of the croupier (the Universe) dealing another favourable card for one of the players at the poker table (Einstein). Who knows what hand those neutrinos are holding

I'm actually somewhat underwhelmed by this.....really, it's just a case of someone having applied and measured GR on a cosmological scale that hadn't been attempted before, mainly because many labs never had equipment sensitive enough to do the work. Given their confidence in GR, this result ought to have been expected and not come as some sort of a surprise. It's more of a reaffirmation than a revolutionary result in favour of GR. An incremental step of confirmation in a particular situation. I would consider the unequivocal detection of gravity waves as a revolutionary result for GR...not this.

[sjastro]

Originally Posted by renormalised

This is not so much a case of "Einstein Strikes Back" as it's a case of the croupier (the Universe) dealing another favourable card for one of the players at the poker table (Einstein). Who knows what hand those neutrinos are holding

I'm actually somewhat underwhelmed by this.....really, it's just a case of someone having applied and measured GR on a cosmological scale that hadn't been attempted before, mainly because many labs never had equipment sensitive enough to do the work. Given their confidence in GR, this result ought to have been expected and not come as some sort of a surprise. It's more of a reaffirmation than a revolutionary result in favour of GR. An incremental step of confirmation in a particular situation. I would consider the unequivocal detection of gravity waves as a revolutionary result for GR...not this.

Gravititational redshift is the weakest of the three (after cosmological and Doppler) and has only been detected in lab experiments (Pound–Rebka), GPS applications, and perhaps the odd double star such as Sirius B.
So finding it on a cosmological scale is significant.

Maybe not as grand as discovering gravitational waves but Einstein has had a bad week.

Regards

Steven

[CraigS]

How did they measure the cluster's mass ?

Mass measurement has undergone quite a lot of 'to-ing and fro-ing' over the last year. I wonder whether they've used the latest techniques for doing this.
(This would seem to be an important factor in reaching their conclusion).

Cheers

[renormalised (Carl)]

Originally Posted by sjastro

Gravititational redshift is the weakest of the three (after cosmological and Doppler) and has only been detected in lab experiments (Pound–Rebka), GPS applications, and perhaps the odd double star such as Sirius B.
So finding it on a cosmological scale is significant.

Maybe not as grand as discovering gravitational waves but Einstein has had a bad week.

Regards

Steven

Yes, I know, but I still don't feel all the excited about it

He could have a bad rest of the year/next year/decade...you never know

[Robh (Rob)]

Steven,

Most interesting.
The exact calculation of mass is not really all that necessary. All that is needed is that there is a greater red-shift for light from the cluster centre compared to that of outlier galaxies.
However, more accurate mass estimation does lead to more accurate red-shift corroborations.

Thanks for posting.

Regards, Rob