Crank this until it's just too darn loud!
Here's the thing about "The Power of Love." Wonderful song, just a landmark of the mid-'80s soundscape.
Doesn't actually fit in the Back to the Future soundtrack - at all. Yes, it's the perfect, driving rock number Marty McFly would enjoy as he's hanging off of truck beds. And so it's technically an acceptable song, in terms of internal film logic, to be playing diegetically in the opening set piece.
But as a commentary on the actual themes of the film, what the hell is "The Power of Love" doing there? Are we truly believing that Marty's sole motivation for returning to the present is to get back to his girlfriend, of which we learn next to nothing neither before nor after Marty's time travel to the past? There is exactly one mention of Jennifer as a motivation to return to the present, when Marty pleads for '50s Doc Brown to help him because back in his time he has a girl. Doc asks, "Is she pretty?" And Marty shows him the flier onto which she wrote her love note.
This is, of course, the pivotal moment of the film, where on that flier they discover the exact upcoming event that can help Marty get back to the future. That's true.
But is that really demonstrative of the "power of love"?
Shouldn't the song be more about "the power of blind fortune"?
And honestly, the key motivation for Marty to get back home is the fact that his presence in the past is slowly erasing his presence completely from the space-time continuum. That's what really gets him off his ass.
I would be more satisfied if Huey Lewis wrote a driving guitar ode to "the power of the impending void."
Talk about existentialism!
Or, if you want to skew to the affirmative aspects of the film, you could go with "the power of confidence," which is by far the most dominant theme. In fact, it's less love that motivates Elaine's attraction to, first her future son, then her destined husband, and it's more her reaction to that prototypical Reagan-era male confidence. Confidence is what makes Marty a promising guitarist capable of blowing out the ears of two successive generations, not to mention such a scrappy street fighter and dashing escape artist. It's what gets George his publishing deal. It's what made Doc crazy enough to steal plutonium from Lybian terrorists. It's what made Lybian terrorists think they could hit a time traveling DeLorean with a paltry shoulder-mounted rocket!
It goes to show how slapdash and haphazard the production of Back to the Future was, where multiple script ideas were cycled in and out, and even Michael J. Fox didn't enter the cast until well into shooting. Maybe at the time that "The Power of Love" was commissioned and recorded for this film, there was a much stronger love story serving as the main theme.
But whatever! The song absolutely worked in the spot it needed to work - because confidence!
When you have a great song, you can be confident about anything!
It's really about "the power of a can't-miss song."
P.S. This film theorized that Lybian terrorists had plutonium in 1985. Never has anything in reality come close. THERE is your science fiction.