Summary. Brian Greene is a respected and credible theoretical physicist who teaches at Columbia and has written several books.
http://en.wikipedia.org/wiki/Brian_Greene
Greene wrote a book published in 2011 about multiple universes called "The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos".
http://www.amazon.com/The-Hidden-Reality-Parallel-Universes/...
When he was doing his book tour for that one, the 9News article was written and features an excerpt from the first chapter of the book.
http://www.9news.com/news/article/182664/509/Is-there-anothe...
Somebody at this IEET site, whatever it is, found the 2 year old article and today published a poor summary of it filled with mumbo jumbo and hand waving. That is what is linked to by OP.
To find more information about how the multiverse theory is testable, presumably the details are in his book, which has fairly good reviews on amazon and is the #4 best seller in the category of Quantum Physics.
A summary of the book's content is present on a wikipedia page dedicated to it.
http://en.wikipedia.org/wiki/The_Hidden_Reality:_Parallel_Un...
Lost in Math - Sabine Hossenfelder[2]
The First Three Minutes - Steven Weinberg[3]
Hyperspace - Michio Kaku[4]
Not Even Wrong - Peter Woit[5]
The Trouble With Physics - Lee Smolin[6]
About Time - Paul Davies[7]
Time Reborn - Lee Smolin[8]
The Elegant Universe - Brian Greene[9]
The Hidden Reality - Brian Greene[10]
The Fabric of the Cosmos - Brian Greene[11]
Quantum Space: Loop Quantum Gravity and the Search for the Structure of Space, Time, and the Universe - Jim Baggott[12]
The Universe Speaks in Numbers: How Modern Math Reveals Nature's Deepest Secrets - Graham Farmelo[13]
Three Roads To Quantum Gravity - Lee Smolin[14]
Programming the Universe: A Quantum Computer Scientist Takes on the Cosmos - Seth Lloyd[15]
Higgs - The invention and discovery of the 'God Particle' - Jim Baggott[16]
[1]: https://www.amazon.com/Something-Deeply-Hidden-Emergence-Spa...
[2]: https://www.amazon.com/Lost-Math-Beauty-Physics-Astray/dp/15...
[3]: https://www.amazon.com/First-Three-Minutes-Modern-Universe/d...
[4]: https://www.amazon.com/Hyperspace-Scientific-Parallel-Univer...
[5]: https://www.amazon.com/Not-Even-Wrong-Failure-Physical/dp/04...
[6]: https://www.amazon.com/Trouble-Physics-String-Theory-Science...
[7]: https://www.amazon.com/About-Time-Einsteins-Unfinished-Revol...
[8]: https://www.amazon.com/Time-Reborn-Lee-Smolin/dp/0544245598/
[9]: https://www.amazon.com/Elegant-Universe-Superstrings-Dimensi...
[10]: https://www.amazon.com/Hidden-Reality-Parallel-Universes-Cos...
[11]: https://www.amazon.com/gp/product/0375412883/ref=dbs_a_def_r...
[12]: https://www.amazon.com/Quantum-Space-Gravity-Structure-Unive...
[13]: https://www.amazon.com/Universe-Speaks-Numbers-Reveals-Natur...
[14]: https://www.amazon.com/Three-Roads-Quantum-Gravity-Smolin/dp...
[15]: https://www.amazon.com/Programming-Universe-Quantum-Computer...
[16]: https://www.amazon.com/Higgs-invention-discovery-God-Particl...