Reddit mentions of Singularity (The Archon Sequence)

The idea that the Tunguska event was caused by a meteor was popular even in the time it occurred, which caused Leonid Kulik to lead an expedition to the incident's epicenter. However, the expedition found no meteorite remains in the area, and were unable to find even a crater at the supposed point of impact. This was not because the epicenter was somehow lost, as pictures from the expedition make clear. Trees were knocked down in an incredibly huge circle around the epicenter, but the ground at apparent point of impact appeared undisturbed.

My own hypothesis for the Tunguska event is that it was caused not by an impact with a meteor, but with a comet. A meteor is a solid body, and a meteor large enough to cause the energy released in the Tunguska event should have been able to reach the surface of the planet and leave a sizable crater behind. A comet, however, is not nearly as solid as a meteor, and far more likely to release its energy in an airburst shortly after entering our atmosphere.

My favorite speculative hypothesis for the Tunguska event is known as the Jackson-Ryan hypothesis, which postulates that the incident was caused by an impact with a microscopic black hole. I was introduced to the hypothesis in a novel, Singularity by Bill DeSmedt, which I whole-heartedly recommend to anyone who enjoys a great Michael Crichton-style thriller. The author has even released the audiobook version of the novel for free!

Most of these are just (free) audiobooks at this point in time, but are excellent Sci Fi stories IMO.

Nathan Lowell

The Golden Age of the Solar Clipper: A Trader's Tale details the story of a young man who is orphaned and kicked off his home planet, into the arms of the trader ship Lois McKendrick. I'd say it's a wonderful start for someone who normally doesn't read Sci Fi, because it focuses so much on his life. You'll be hard-pressed to believe that there aren't people who spend months at a time hauling goods between the stars.

• Quarter Share (print)
  
• Half Share
  
• Full Share
  
• Double Share
  
• Captain's Share
  
  Christiana Ellis
  
  Space Casey is the comedy of this whole bunch. More along the lines of a radio program, it's set in space, with the wily young Casey, her stolen ship Al, and their pet, uh.. thing. A very enjoyable story, and a good laugh!
  
  
• Space Casey
  
  Jon Armstrong
  
  Grey is set in about the strangest world you can imagine, where fashion, celebrity culture, and gore are commonplace. The pull of society on Michael Rivers sends him on an impossible quest to win the hand of his beloved Nora and find out the secret of his birth.
  
  
• Grey (print)
  
  Bill DeSmedt
  
  Here we're getting into the heavier stuff, and trust me when I say you're going to learn a lot. Singularity surrounds the mystery of the Tunguska event of 1908, and the implications aren't pretty. One of the few time travel stories I find plausible.
  
  
• Singularity (print)
  
• Doctor Jack's Soapbox Seminars (not a sci fi story, but a series of lectures on the science behind Singularity)
  
  J.C. Hutchins
  
  7th Son is getting more into the horror/thriller genre, but I'd say it's no less Sci Fi. Cloning, mind copying, secret DARPA projects, conspiracies, the list goes on and on.
  
  
• 7th Son: Descent (print)
  
• 7th Son: Deceit
  
• 7th Son: Destruction
  
  
  
  Edit: found some print copies