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xkcd #2932: Driving PSA
(imgs.xkcd.com)
Alt text:
This PSA brought to you by several would-be assassins who tried to wave me in front of speeding cars in the last month and who will have to try harder next time.
At 100 km/h (low-end highway spreed), or 1,666 m/minute, or 27.7 m per second, a 2 second gap leaves approximately 56.6 m (185.6 feet) between cars. With the average car length being ~4.9 m (~16 feet), even the absolute worst driver can merge in a space ten times the size of the average car, assuming they're matching highway speed.
Most people have no actual concept of how long 2 seconds actually is or how much space it would leave in reality.
Yeah, obviously you "can" merge, but in doing so you insert yourself into the middle of a 2 second gap creating 2 × less than 1 second gaps. Like I said, in this hypothetical everyone is a perfect driver that always follows the rules, so that's not an option.
For that matter, the driver behind should see that you are about to merge into a gap that's too small and slow down to leave a space that's at least 4 seconds big.
I'd also like to point out that your attitude to driving is terrible, the size in meters of anything on a highway is irrelevant, 2 seconds is not a lot of time to react and slow down a car at 100, and that just because you "can" do something doesn't mean you should.