Is speculation in multiverses as immoral as speculation in subprime mortgages?

Perhaps Anti-Tyson is a little harsh, but soon after I see a great discussion by Neil deGrasse Tyson on science being driven by passion and curiosity, I read some blather from someone who’s basically pissed off that a physicist wrote something other than a physics textbook. Speculating on the metaphysical implications of science isn’t my particular cup of tea, but it’s not up to me to tell others that they can’t engage in it — as long as they don’t think they’re doing science. One never knows what speculation might spark an actual scientific advance, or when one might recognize that there is an actual falsifiable scientific principle embedded in one of those thoughts. (Leo Szilard is said to have come up with the idea of the fission chain reaction by seeing a traffic light change. Who the hell knows where inspiration comes from?)

I think it’s worth noting that John Horgan is the author of The End of Science, which I believe is the book (and concept) that Tyson was blasting in the interview as being shortsighted.

Is theorizing about parallel universes as immoral as betting on derivatives based on subprime mortgages? I wouldn’t go that far. Nor do I think all scientists should be seeking cures for cancer, more efficient solar cells or other potential boons to humanity. But scientists should, at the very least, investigate the world in which we live rather than worlds that exist—as far as we will ever know—only in their imaginations.

Now, I haven’t read the book, and I can’t say for sure how it is presented. If it’s being misrepresented as actual physics, then Greene is in error. But that doesn’t seem to be the complaint. Horgan knows its speculation, because he identifies it as such. His objection appears to be that a physicist was doing something that’s not physics! How dare he do that! If a physicist wants to write a book about metaphysics, or poetry, or whatever, who the hell is John Horgan to tell him/her otherwise, or to say what we do with our (free) time?