**By David Harris**

The last day of Convergence had a lighter schedule but started off just as intensely as the rest of the meeting.

**Peter Olver** delivered a lecture on the mathematics of Noether’s theorems, a fundamental piece of mathematics that has play an outsized role in physics since its development 100 years ago. Olver co-presented a public lecture on Noether on Monday night but today he went into the detailed mathematics. I won’t go into any of that here but will just mention why Noether’s theorems are important.

From a physicist’s point of view, Noether’s theorems relate symmetries in nature to conservation laws in precisely calculable ways. They say that any continuous symmetry gives rise to a corresponding conservation law. For example, the fact that nature has translation symmetry (i.e. that the laws of physics are the same in all locations) means that momentum is conserved. The fact that nature has time translation symmetry (i.e. that the laws of physics are the same at all times) means that energy is conserved. The fact that nature has rotational symmetry (i.e. that the laws of physics are the same no matter which direction you point) means that angular momentum is conserved.

## A Big-Picture Panel

The final session of the conference was a panel Q&A moderated by **Ian O’Neill** of Discovery News. Appearing with him were quantum “optician” Immanuel Bloch, exoplanet hunter Sara Seager, particle physicist Stefania Gori, and gravitational wave sleuth Patrick Brady.

It is impossible to summarize 90 minutes of conversation in this space but the participants all had interesting things to say about the current state of their fields and potential futures.

**Patrick Brady** commented that, “We just don’t know what we’re going to see,” when facilities such as Advanced LIGO start operating in the next few years. “We need to make sure we do as well as we can with the instruments we build today – find those corners where there is confusion and stay in a state of confusion for as long as we can.”

**Stefania** Gori clearly thought that the search for dark matter is the main target for particle physics in the near future but that “one of the important questions is to define our guiding principles.” She said “Supersymmetry has been the most studied framework,” but asked whether that is the framework we really want to study. How do we probe the additional theories that haven’t been probed up until now? We also need to see what experiments will be running and what data we’ll have access to.

**Immanuel Bloch**was excited about the possibilities for using small atomic systems for probing bigger questions: “Could we learn something from the low energy experiments about the expansion of the universe? The advantage of the lab is that we can change the initial conditions and not be constrained by observation.” He also commented on the role of smaller scale experiments: “I think people should be more open to those experiments. They’re having a hard time getting seen and getting funded.”

**Sara Seager **said that exoplanet searches have a fairly clear future in the near term. “Right now we know what our future is as long as we can build our space- and ground-based telescopes. We just need to look at more and more stars in better detail. It’s not enough to just find one that might be like Earth, we need dozens and dozens.” She also said that, “we’re so busy finding exoplanets that we often don’t think too much about what to do next.” However, she did warn that there will be claims of life but some will just be false positives and claims on the edge of detectability and sometimes just signs of a biosignature molecule rather than evidence of actual life on exoplanets.

All the participants agreed that the meeting was extremely valuable for bringing together people from different fields, for asking tough questions, and an experiment worth repeating.

That’s all from me at Perimeter Institute for the Convergence conference. You can watch the archive of all the talks here and follow activities of Perimeter on Twitter.

**David Harris is a theoretical physicist turned science journalist and ****communicator. He is the on-site rapporteur for the Convergence ****conference at Perimeter Institute.**

As this inaugural event drew to a close at Perimeter, attendees agreed that Convergence has been an experiment worth repeating.