Does the alignment of the Earth and Sun and Galactic Center cause some kind of gravitational boost that creates problems on Earth?

No, the alignment has already been happening every December 21 for years.  No cosmic event will rock the planet this year because of this alignment on December 21 or it would already have happened to us.  The alignment is just something ancient people chose to mark this moment in time.  The Bible also describes astronomical alignments, most eloquently through the metaphor of an ancient Jewish wedding ceremony.  I believe that ceremony, which Christians know as Christ coming for His bride, will take place in 2019, and that the astronomical clues in the Bible are very specific on the timing.

Your date in 2019 is seven years off from what everybody is talking about in 2012. What do you expect to happen when the Mayan Calendar ends on December 21, 2012?

Their calendar doesn't really end on that date any more than ours ended on December 31, 1999.  It's more like the point when an odometer flips from all nines to all zeros.  But the ancient Maya did expect world-changing events at this time. This date is the end of the Mayan Long Count -- the largest (5125 year) cycle within their calendar.  Their calendar will start over with a new Long Count cycle just like we start a new year in January.  But the Maya did believe this point in time would mark the end of the world as we know it and the transition to a new world.  I think they viewed the transitional years from 2012-2019 as the first years of the new system of things in the next world.  I think the Bible describes these transitional years as the last years of the world we know now.  I believe the Maya date of December 21, 2012 is also the start of the seven year tribulation mentioned in the Bible -- and that Judgment Day is in 2019.

You seem so certain about the exact dates of these events. Doesn't the Bible tell us that no one can know the hour or the day?

Many people cite Matthew 24:36, which in a modern English Bible like the NASB says "But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone."  But where we read the word "knows" the original Greek word is "oiden" which is a past tense verb, meaning "has seen."  No one knew then, when Jesus was speaking in the year 33.  But the Bible also clarifies that all secrets are revealed before prophetic events occur.  Also understand that Jesus was making a reference to the timing of a future wedding to His bride.  In an ancient Jewish wedding, the groom to be starts the wedding arrangements and then goes to his father's house to build an addition where he will live with his bride.  The groom does not decide when the addition is ready; the father has the final say and will tell his son when it is time to get the bride.  So when disciples asked Jesus about timing this future event, He had not yet even gone to His Father's house to start "preparing a place for us."

There is actually a great deal of astronomical symbolism encoded in the Bible about these future wedding events.  Many steps in an ancient Jewish wedding ceremony mimic what heavenly bodies will be doing starting in 2012 but especially in late 2019.  With modern astronomical software we can know the hour and the day, even down to the minute, when certain events in the wedding ceremony take place in the sky.  The Bible also tells us in Haggai 2:20-21 that God will start to "shake the heavens and the earth" on the 24th of the month of Kislev, the night before Hanukkah begins.  Matthew 24:20 mentions winter and the Sabbath day... And December 21, 2019 is the first day of winter, it is a Saturday, it is the day before Hanukkah, it is exactly seven years after the end of the Mayan Long Count... There is much more detail to pin down specific dates in 2019 and 2012 but that's why I wrote a book...