Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. It’s been 250 years since the United States decided it was no longer interested in being part of Great Britain. To celebrate the momentous anniversary—called a semiquincentennial —the non-profit America250 has numerous events planned including something quite timely.  A roughly 2,000-pound time capsule will be buried at Philadelphia’s Independence National Historical Park on July 4, 2026. The capsule is intended to safeguard a snapshot of America today for another 250 years.…