Still Traveling

I’m still traveling this week, so this will  be a short post.

Last year, when I went to Amplitudes I left Europe right after. This felt like a bit of a waste: an expensive, transcontinental flight, and I was only there for a week?

So this year, I resolved to visit a few more places. I was at the Niels Bohr Institute in Copenhagen earlier this week.


Where the live LHC collisions represented as lights shining on the face of the building are rather spoiled by the lack of any actual darkness to see them by.

Now, I’m at Mainz, visiting Johannes Henn.

Oddly enough, I’ve got family connections to both places. My great-grandfather spent some time at the Niels Bohr Institute on his way out of Europe, and I have a relative who works at Mainz. So while the primary purpose of this trip was research, I’ve gotten to learn a little family history in the process.

7 thoughts on “Still Traveling

  1. Martin

    i ready that the new particle at lhc couldn’t be a graviton and it listed several reason which i think are bogus. firstly it said that GR does away with gravity as a force. true, but that doesn’t mean we can’t have an additional gravity-like force which energetic/heavy objects would generate en masse. so a graviton isn’t required to warp space/time and these effects of GR but is an additional force, and GR free’d up the graviton to do whatever it wanted! Second bogus reason the graviton had to be a light particle, no it doesn’t. it only has to be light if it has to be responsible for warping space/time, which it isn’t. a high mass graviton could actual have the opposite effect of gravity in that it would be a force that imparts accelleration along the existing space/time and not be able to change space/time ie the direction of travel which stays the same. could explain why galaxies rotate the way they do


    1. 4gravitonsandagradstudent Post author

      So, the first reason you read is indeed bogus. In GR, gravity is space-time, but it also gives rise to gravitons. (My N=8 supergravity handbook has a section about this. Basically, it’s not that GR sets the graviton “free” to not be space-time. Rather, it’s that there’s actually no contradiction between being space-time and being gravitons.

      As to the second reason, the graviton itself needs to be massless, but it’s quite possible (especially if space has more than four dimensions) that there are also related, massive particles. (I don’t think they’d generally have the effect you describe, though.)

      I don’t know whether anyone has been seriously considering that the bump seen at the LHC could be due to massive gravitons. It’s not an idea I’ve heard suggested, anyway. Regardless, the rumor is that the bump was just a statistical fluke, and that it went away in the new data.



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