"The question is, 'Can you communicate with those other universes if they are running on the same platform?," she said.

If we share any form of resources then its going to be possible either through a timing or storage channel attack - this is simplified but here's an example of two vms communicating via the hypervisor:

http://www.idontplaydarts.com/2012/08/data-exfiltration-thro...