Advanced Propulsion Design for Space Exploration

Here's another one I got via Instapundit and Kurzweil Accelerating Intelligence blogs.  I read the abstract and thought it interesting, so I downloaded the pdf file and spent the last few hours perusing this thing.

Not that I know anything about the subject matter, just as a matter of curiosity.  A few items of interest, to wit:
1) it is not necessarily feasible for putting humans in orbit because of high g forces  2) it may have the potential to transport very large objects into space at low cost per kilogram 3) the technology required is not unreasonably demanding.   Now I am taking the guy (Parkin) at his word that thing will do what he says it can do.  If he is right, then this concept has a chance.

How does it work?  It uses microwave energy to heat hydrogen and uses that as thrust to lift the rocket into space.  For a more detailed explanation, see the abstract and pdf file if you are interested.

Update:  It uses hydrogen as a propellant, but this would seem to be a problem when the hot
hydrogen meets the oxygen in the atmosphere.  Maybe it would go boom instead of going up.
This idea was a doctoral thesis, so I don't how that turned out.

Update 2:  I skimmed over the document again and found no discussion of this hydrogen issue.  Perhaps it isn't an issue and I am mistaken.  Or it could be an oversight by Parkin.  At any rate, I'll still say this looks like an interesting proposition.