Twenty years ago I had a Compuserve account.
It is NOT "scientific thinking" to say "someday science will figure it out." It IS scientific thinking to make conjectures based on all the evidence as we currently understand them. While it is important to understand that there will be breakthroughs ahead, and that there will be something else discovered that we have no idea about now, we can tell what those things will be, and an expectation that we will discover ANYthing that we want is exactly the same as fiction.
We do know, right now, that interplanetary space, even interstellar space, is awash in energy. Lots of radiant energy for one, there's the solar wind, and lots of hydrogen. There are many ideas out there on how we can use that energy.
The hydrogen ramjet idea is over 30 years old, and would be a great source of fuel once a spacecraft is already traveling at high velocity. Solar sails should work fine for acceleration away from the sun, but the craft would need to be very small compared to the sails, and it would be no good for getting back home (you cannot tack against the wind in space).
Science must be skeptical in the face of goals based on unknown speculation. We have to temper our wishes with our reality (as we understand reality to be). Going into orbit around the Earth is OLD news. It has been done for forty years now. Half a century of orbiting the earth. So now a Spaceport "is going to be built" in order to take people into orbit. How much of a step is that?
We are also now thinking and planning (not building yet) a scheme to get one or two people to Mars and back. I am certain that we will get there, and probably within my lifetime. But large groups of people going to Mars? Not so very soon.