Speed of Light, Time & the Revati Story in Puranic Lore

Modern physics says:

Nothing travels faster than light (as far as we know).

Speed of light ≈ 186,000 miles/second (≈ 3,00,000 km/s)
1 light-year = distance light travels in one year

In some traditional commentaries on Vedic verses and in later works, we find:

A numerical estimate of light speed using units like yojana and nimisha
A Puranic story about King Raivata and his daughter Revati visiting Brahma-loka, where time runs differently — very similar to the modern idea of time dilation.

This article explains both in simple language.

1. Ancient Calculation of Light Speed

A famous traditional verse (quoted by later scholars) says, in essence:

In half a nimisha, light travels 2,202 yojanas.

To unpack this, we need to understand two old units:

Yojana – a unit of distance
Nimisha – a unit of time

1.1. Time Unit: Nimisha

Ancient Hindu time division:

15 nimishas = 1 kashtha
30 kashthas = 1 kala
30 kalas = 1 muhurta
30 muhurta = 1 day

So:

1 day = 15 × 30 × 30 × 30 = 405,000 nimishas

Modern day:

1 day = 24 hours
= 24 × 60 × 60
= 86,400 seconds

So we can relate them:

405,000 nimishas = 86,400 seconds
1 nimisha = 86,400 / 405,000 seconds
≈ 16/75 seconds ≈ 0.213 s
½ nimisha = 8/75 seconds ≈ 0.106 s

1.2. Distance Unit: Yojana

There are slightly different traditional values; a common one used is:

1 yojana ≈ 9 miles

The verse says:

In half a nimisha (½ nimisha), light travels 2,202 yojanas.

So in 8/75 seconds:

Distance = 2,202 × 9 miles
≈ 19,818 miles

Speed ≈ distance / time:

19,818 miles ÷ (8/75 seconds)
= 19,818 × 75 / 8
≈ 185,000–187,500 miles/second (depending on rounding)

This is astonishingly close to the modern value:

Modern physics: 186,000 miles/s
Traditional calculation: ≈ 187,500 miles/s

1.3. Quick Comparison

| Source | Value (approx.) | | :--- | :--- | | Traditional computation | ~187,500 mi/s | | Modern measurement (physics) | 186,282 mi/s |

📌 Important Note
We cannot prove that ancient scholars had laboratory-style measurements like modern physics. However, the scale and closeness of the number show they were thinking in very large distances and high speeds.

2. What is a Light-Year? (Simple)

Because space is so huge, scientists use light-years:

1 light-year = distance light travels in 1 year
Roughly ≈ 6 trillion miles (≈ 9.46 trillion km)

Example: A star 4.3 light-years away (like Alpha Centauri). The light we see today left that star 4.3 years ago. So when we look into the night sky, in a way, we are looking into the past.

3. Time Dilation: What Happens Near Light Speed?

Modern relativity says:

When you travel close to light speed, your time slows down compared to people at rest.
Your aging process slows and your clock ticks slower.
You might travel for what feels like a short time to you, but centuries may have passed on Earth.

This effect is conceptually very close to relativistic time slowing down, where time almost stands still for the traveler.

4. The Revati Story: Time Runs Faster on Earth

Now let’s connect to the Puranic story about King Raivata (Kakudmi) and his daughter Revati.

4.1. The Problem: Finding a Perfect Groom

King Raivata searched the entire Earth for a suitable husband for his highly virtuous daughter Revati, but felt no one was worthy enough. So he decided to ask Brahma himself for guidance.

4.2. Journey to Brahma-loka

Raivata traveled to Brahma-loka beyond Earth and earthly time. There, Brahma was listening to a celestial music performance. Raivata respectfully waited until the music ended to ask his question.

4.3. Brahma’s Shocking Answer: Time Difference

Brahma smiled and explained that time flows differently in his realm. While Raivata waited for a short while, many ages (Yugas) had passed on Earth. Dynasties had changed, and the world he left behind no longer existed.

Brahma advised him that in this new era (the 28th Dvapara Yuga), a suitable groom lived in Dwaraka — Balarama, the elder brother of Sri Krishna.

4.4. Return to Earth: A Changed World

Raivata and Revati returned to find a completely changed planet. Their old kingdom was gone. Revati married Balarama, and tradition even mentions how she appeared much taller (coming from an earlier age), requiring a divine adjustment to match the physical proportions of the new era.

5. Light-Speed & Revati: The Connection

This story illustrates the concept of time dilation perfectly:

To reach Brahma-loka, the travel is imagined as extremely fast.
While the travelers experience only a short duration, hundreds of years pass on Earth.
This aligns with the notion that time is not absolute—a core principle of modern relativity.

6. How to Read This Wisely

Whether understood as a symbolic-philosophical insight into the nature of existence or as a mythic-scientific parallel to modern physics, these stories are fascinating in how they echo ideas that modern science is now exploring formally.

Ancient Bharatiya minds were not limited by the tools of their time; they dared to conceive of a universe where time itself was flexible and the cosmos was vast beyond imagination.