Handling Pre-1970 Timestamps
The Unix Epoch began on January 1, 1970. But history didn't start then. To represent dates before the epoch, we use negative numbers.
How it Works
| Date (UTC) | Timestamp |
|---|---|
| 1970-01-01 00:00:00 | 0 |
| 1969-12-31 23:59:59 | -1 |
| 1960-01-01 00:00:00 | -315619200 |
| 1900-01-01 00:00:00 | -2208988800 |
Language Support
const moonLanding = new Date('1969-07-20T20:17:40Z');
console.log(moonLanding.getTime());
// Output: -14182940000 (Milliseconds)import datetime # From timestamp dt = datetime.datetime.fromtimestamp(-14182940) # Works fine on modern OS/Python versions
t := time.Unix(-14182940, 0) fmt.Println(t.UTC()) // 1969-07-20 20:17:40 +0000 UTC
The 1901 Problem (32-bit Integer)
Just like the Year 2038 problem (overflowing positive 32-bit integers), there is a lower bound for signed 32-bit integers: Friday, December 13, 1901 20:45:52 UTC (Timestamp: -2,147,483,648).
If you are working with historical data (e.g., birth dates from the 1800s) on a legacy 32-bit system or using a 32-bit integer column type, you will encounter overflow errors.Always use 64-bit integers (BIGINT) for storage.
Frequently Asked Questions
Are negative timestamps valid?
Yes! The Unix timestamp is a signed integer. -1 represents Dec 31, 1969, 23:59:59 UTC.
Do all systems support negative timestamps?
Most modern systems using signed 64-bit integers do. Older systems or unsigned integer implementations might fail or wrap around.
How far back can I go?
With a 64-bit signed integer, you can go back 292 billion years, which predates the universe. With a 32-bit signed integer, you can only go back to Dec 1901.