Manually Changing Your iPhone’s Time Settings To This Exact Date Will Crash Your Device. Seriously, Don’t!
If you’re really bored and decide to see what happens when you manually change your iPhone’s time settings to January 1, 1970, you close your eyes, say goodbye to your device.
CNN Money offered a hypothesis: “January 1, 1970 is the earliest date you can set your iPhone to. If you turn your date and time settings to manual (please don’t do this), and scroll the calendar back as far as you can go (seriously, don’t do this), you can only go as far back as January 1, 1970.”
Now, why would scrolling all the way back to January 1, 1970 (00:00:00 in Unix time) turn your iPhone into a brick? If your time zone isn’t GMT, your iPhone might think you’re in a time before January 1, 1970 — or before zero. Though Unix time can be negative, it’s possible that something about that makes your iPhone go haywire.
There’s a video of an iPhone user setting the device’s clock back to January 1, 1970. And then when the phone is powered off and back on again, it’s stuck forever on the greeting screen.
So, you see?