In Jainism, the “age of the earth” is not seen as one finite line with a beginning and an end. Instead, time is beginningless and endless, moving in repeating cycles. Within these cycles, the appearance of Tirthankaras is fixed and law‑governed.

Let’s keep it very simple.

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1. Jain view of time and eras (Kāl‑chakra)

• Time goes in an eternal wheel (kāl‑chakra), not a straight line.
• Each full cycle has two halves:

1. Utsarpiṇī – ascending / improving half 2. Avasarpiṇī – descending / declining half

• Each half is divided into 6 eras (ārās), from very happy and spiritual to very miserable and irreligious.

We are now, according to Jain tradition, in:

• Avasarpiṇī (descending half)
• 5th era (Duṣamā) – much sorrow, weak spirituality, no new Tirthankaras appear now. ( jainknowledge.com)

So, even though science talks about a finite “age of the earth,” Jain Dharma talks about an unimaginably long, repeating cosmic time around it.

You can read a simple explanation of the Jain time‑cycle here

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2. Tirthankaras within this time‑cycle

Within each half‑cycle (each Utsarpiṇī and each Avasarpiṇī):

• There are exactly 24 Tirthankaras in our human region (Bhārat Kṣetra).
• This number never changes: not 23, not 25 – always 24. ( jainknowledge.com)
• Both Digambar and Śvetāmbara agree on this fixed number of 24 per half‑cycle.

So across infinite cycles of time:

• Total Tirthankaras are innumerable,
• but in our present half‑cycle of this region, there are 24, from Ṛṣabhadeva (Ādinātha) to Mahāvīra.

You can see a simple Q&A on “why only 24 Tirthankaras” here

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3. Our current position: which Tirthankaras, which era?

For our present Avasarpiṇī in Bhārat Kṣetra:

• The 24 Tirthankaras already appeared, starting with Ādināth Bhagwān (Ṛṣabhanātha) at the beginning of this Avasarpiṇī, when humans were extremely tall, long‑lived and very advanced. ( jainknowledge.com)
• The 24th and last of this half‑cycle is Bhagwān Mahāvīra.
• Now no more Tirthankaras will appear in this Avasarpiṇī; the spiritual condition is too low. ( jainknowledge.com)

In the next half‑cycle (the future Utsarpiṇī) of this region, again 24 new Tirthankaras will arise, different individuals, but with the same perfect qualities.

A short Q&A on “future Tirthankaras” is here

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4. How this relates to “finite earth age”

From a Jain perspective:

• The physical form of this world (what science calls “earth”) can change, form and reform many times.
• But time and soul are beginningless (anādi) and endless (ananta).
• The pattern of eras and 24 Tirthankaras per half‑cycle keeps repeating over and over in this vast framework.

So, even if modern science treats the earth as having a finite measurable age, Jain Dharma says that within an eternal, cyclic universe there are endless time‑cycles, and in each relevant half‑cycle of our region 24 Tirthankaras appear to re‑establish the path of liberation.