Liquid Tension Experiment is the band featuring current Dream Theater guitarist John Petrucci and keyboardist Jordan Rudess alongside ex-Dream Theater drummer Mike Portnoy and King Crimson bassist Tony Levin. The group put out their first record in 21 years Liquid Tension Experiment 3 last year, and according to Rudess we might not have to wait another 21 years for (what we're assuming will be called) Liquid Tension Experiment 4.
Rudess said in an interview with Ghost Cult Magazine that "there will certainly be more [Liquid Tension Experiment material], although there's no date right now when it'll happen. We were interrupted by a few things, but… looking forward to when that happens again. It was so much fun the last time. It was great to get together with Mike Portnoy and the guys and that was just something that I will welcome again."
Liquid Tension Experiment 3 was the first time Petrucci and Rudess played with Portnoy on a record since his departure from Dream Theater in 2010. And given the quality of Liquid Tension Experiment 3, it's safe to say that exactly zero of their chemistry has degraded over time.