Let's do some rock 'n' roll physics. If the success of a rock star equals the force exerted by spectators at one of his concerts, then how popular is Richard Marx? Well, I'm no science whiz, but speaking as someone who spent over an hour compressed between a restraining wall and thousands of screaming fans, I can say without reservation that Marx is the next big thing.The Marx show definitely appealed to the younger set, especially young teenage girls, who flocked around the stage and screamed every time he wiggled. But there was enough meaning in his music for people older than 15 as well.

Last night was the one-year anniversary of Marx's tour, and the months of practice were evident. His band was tight and almost always in tune. I was a little concerned about the quality of Marx's voice, considering he'd been touring for so long, but he sounded great. He didn't do much cheating, either - only once or twice did he sing in a more comfortable key or hit a lower note than usual.

Not surprisingly, his performance of his hits drew the greatest response from the people in the packed stadium. "Endless Summer Nights" and "Hold on to the Nights" had all the girls swooning (f course, it could have been the heat, but I'll give him the benefit of the doubt). A rousing version of "Don't Mean Nothing" had the crowd singing backup. Conspicuously absent from the 80-minute show was "Should've Known Better," however.

Some pleasant surprises were a hip a cappella version of "Lean on Me" in five-part harmony that had the crowd singing along, and a fun cover of the Tubes' "I'll Talk to You Later," which got everyone dancing. I enjoyed it even though some 300- pound football player with a girl on his shoulders stepped on my foot. Marx also performed a few new tunes, including "Living in the Real World," which is bound to be big in the hit world soon.

As I was limping out of the stadium, I stopped to chat with two girls who had just spent $23 each for official Richard Marx tour T-shirts. They were dripping with sweat (but so was I), and one looked as if she was developing a black eye from injuries incurred as she was trying to get to the stage, but they were both smiling broadly. They, like just about everyone else I saw, had a great time.

The evening's other attractions, a performance by a dance team called Razzmatazz and a fireworks show, were fairly well-received, but Marx was the show. And this is probably just the beginning for him. As his fans get older and more numerous, they will be able to push the rock 'n' roll success equation to the limit.

MUSIC