The center of the milky way is approximately 27,000 light years away. This is roughly 27,000,000,000,000,000 Kilometers. (27*1016 for those who prefer Scientific Notation) This is roughly 162,000,000,000,000,000 miles. Using NASA’s New Horizons it would take 440,313,111.5 years to get there. So if it were there today, it would have had to have been launched during the end of the Ordovician Period, near the beginning of the Silurian era. Which of course would be impossible because land plants were just starting to show up. If we we’re to have launched the New Horizons from the dawn of humans 200,000 years ago, we could be 12.264ly away. For the sake of simplicity we’ll say 12ly. We’d be past our closet neighboring stars, and able to get to quite a few. Our nearest neighbor; Proxima Centauri; we could get there and back again. But really, modern humans have only really been around for 50,000 years. That’s enough to go about 3 light years with the New Horizons. Not enough to get us to Proxima Centauri, but it does get us an ELO album. It’s also still way too long. Even with multi-generational traveling. It should be noted that Voyager I which left Earth in 1977 (not to be confused with the launch of Voyager in 1995), wouldn’t make to Proxima Centauri for another 72,000 years. so we’ve shaved roughly 5,000 years off the journey in 30 years of space travel. (New Horizons was launched in 2006)
So I’ve scaled in the requirement to one lifetime, and since I don’t see the USA as the only source of people on the planet, we’ll use 70 as the average. (for the record, 78 is the average for the USA) So really, one average lifetime for the current occupants. Obviously we can’t be expected to travel from womb to grave, so we have to cut that down a bit. We’ll say someone traveling their whole practical adult life. say from age 25 until age 50. This gives them time to grow up, get educated, travel, return, then spend the same time teaching what they have learned to another generation until their expiration date. How far can we get (and return) in 25 years? only 4,599,000,000 (that’s 4.6 Billion) miles. If I had a dollar for every mile I’d only rank 173rd in the Forbes list. It would be enough to build a manned spacecraft (maybe) which would be entirely more practical to travel in. The fastest manned machine thus far was/is the Space Shuttle at 17,600mph. This is a far cry from 42,000mph of the New Horizons, but it is practical. this drops us down to a trip of 1,927,200,000 miles (then back). Where does that get us? Not quite to Pluto on it’s closest orbit. Not even to Neptune, We could get to Uranus, all dirty jokes aside. It is only 1.6 Billion miles on it’s closest orbit. This leaves time to spare.
Most of us are not going to have a space shuttle, but we will soon have commercial space flights. I’m betting this will become affordable within my lifetime. Remember it was only 10 years ago that Plasma TV’s were $20,000. The SpaceShipTwo travels at 2,600 mph. Depending on orbits (and ignoring that it’s a suborbital spacecraft) You could reach Mars in somewhere between 547 days (closest orbit) to just under 11 years (farthest orbit). But a year and a half is a bit much to sit in that little craft. We need something closer. The Moon is only 238,857 miles away (yes, I know it varies) New Horizons zipped past the moon in 8.5 hours. But it didn’t need to slow down for entry. Apollo missions did it in roughly 3 days. Still too long to sit in a tube. So what we need is a time of around 8.5 hours with the ability to stretch your legs now and then. It needs to be practical and affordable now. I know, a 737. One of the most popular and numerous jet airliners on the planet. It travels at an average cruising speed of 485mph. How far does that get you in 8.5 hours? 4,122.5 miles. Why you could get from Hartford, CT to Vienna. Of course you’d still have to get to Hartford. From Detroit? How about Sweden? Brazil? Still too far? you know what’s closer? Ireland is only 3,470 BTW to all of you in and in/out of Éire that followed the link, I’d take a tchotchke on your next return :-), Don’t want to travel across the pond, I know something closer still. In just 2,971.2 miles you could be in Anchorage. Savannah to Anchorage? well it’s 150 miles further. But you know what’s closer than Detroit? Berkeley. It’s only 2,000 miles. It’s generally a 5.5 hour flight. In comparison, it has taken me 6.5 hours to type this up.