On The 163 Year Discrepancy

When we check dating of events of Galut Bavel in Jewish chronology against secular dating, we find a striking discrepancy of 163 years:
Destruction of the 1st Beit HaMikdash

• Secular Dating: 3175 (586BCE)
• Jewish Dating: 3338 (423BCE)

There is basic agreement regarding the beginning of the 2nd Beit HaMikdash Period being the year 3408 (353BCE).
So we seem to have a contradiction.

• According to Secular Dating, Galut Bavel was 233 years long
• According to Jewish Dating, Galut Bavel was 70 years long (very close to 30% of the Secular Dating)

To gain a better understanding of how this discrepency came to be, I recommend reading Moshe Lerman's article on Arutz Sheva: "Why Do We Live in the Year 5765?"
Our question here, however, is not how our chronology or the secular chronology was determined. The question is this: How do we understand the discrepency?
The dating of the Churban of the 1st Beit HaMikdash to 3175 (586BCE) is on fairly solid ground, from astronomical data in Babylonian records. From a physical perspective, the secular dating is truth. Does that make the traditional Jewish date of 3338 faleshood? Is the physical perspective the only true perspective? Of course not.
The chronology taught in the Jewish Calendar as derived in Seder Olam Rabba represents a deep reality. It is the reality of the 6 Days of Creation, the Sin of Adam HaRishon, and the 6000 Years of Tikkun to bring Mankind back to Gan Eden before the 7th Millenium. The chronology takes us from the Tanach and shows us just where we stand in relation to this 6000-year story.
Our calendar starts with and parallels the 6 days of Creation. The chronology itself indicates the timing for the Geulah, in parallel to the 6th Day. The GR"A makes it explicit in his commentary on chapter 5 of Sifra Ditzniuta.
Since the 6000 Years are a hint to the process of Geulah, and the setting of the calendar is based on the traditional (yet mathematically inaccurate) cycles of the Sun and Moon, then there must be a relation between the Geulah and the cycles that make up the calendar. This is mentioned by the early Kabbalists, and indeed some of them made Geulah calculations (which did not prove to be correct) based on the number of cycles to have passed. Birkat HaChamah marks this relation, yet as I have mentioned before, the 28-year cycle by itself is not sign of the Geulah.
In a way, the different symmetries of the calendar, the mathematical beauty of it all, was programmed in to the calendar for us to find.
In the Zohar, the following is pointed out:
In all of th Torah, it is never written that Hashem made the earth in 6 days. The exact phrasing in Hebrew is:

כי ששת ימים עשה ה' את השמים ואת הארץ

To translate literally: For six days G-d created the heavens and the earth. Inserting the preposition "in" is definitely the easy way to read this. However, the necessary letter ב is simply not there. One of the implications is that the purpose of creation is the 6 "days", or 6000 years.

So how do we relate this back to the 163 year discrepancy? The men of the Great Assembly, among them prophets, determined the date, as Moshe Lerman explains. Through the prophetic insight they had, they determined that the 2nd Beit HaMikdash was built in the year 3408. They saw that 70 "years" had passed since the destruction of the 1st Beit HaMikdash until the construction of the 2nd. Their insight was to realize where they stood in the 6000 years of history. From the beginning of the 2nd Beit HaMikdash period, the correlation is straightforward between secular and Jewish chronologies.

Perhaps the most surprising of all is this: I have found reference in a very kosher and old source leading me to believe that the dating of 3175 for the destruction of the 1st Beit HaMikdash is true (from a Torah perspective) as well. Perhaps I will be able to elaborate on this one day.