Since I'm not a professional and don't play one on TV, take this one with a grain of salt.
Some (many) of you may have seen sci-fi shows like "Sliders" that had plotlines where the main characters crossed over into other, parallel universes. I certainly enjoyed them because the possibilities were endless. But let's take a look at one of the most famous equations of all time:
So, if you happen to be a supremely lucky individual who ventures to another universe, remember this: Don't bring back anything. Not a speck of dust, lunch (in your stomach), or breath in your lungs. If you do, all of Einstein-ian physics will no longer be valid and the Earth will probably explode... :-)