How can space travel be like world travel?

[Bullgrit]

How fast would space craft need to move for Solar System travel to be like modern world travel?

How fast would space craft need to move for Milky Way travel to be like modern world travel?

How fast would space craft need to move for intergalactic travel to be like modern intercontinental travel?

A world traveler, today, can get to just about any country on the Earth in what, less than 24 hours? Drive to the airport, hop a plane. Maybe change planes once or twice. Land on the other side of the planet for a week's vacation.

What multiple of light speed must we reach to make planetary, star, and intergalactic travel as relatively common and easy as world travel today?

Bullgrit

 

[Umbran]

A world traveler, today, can get to just about any country on the Earth in what, less than 24 hours? Drive to the airport, hop a plane. Maybe change planes once or twice. Land on the other side of the planet for a week's vacation.

You can get to any major hub in the matter of a day. Getting to a backwater town in a remote, difficult area (say, the Andes or Himalayas) will still take most normal folks quite a bit longer.

For things off our planet, the scale ramps up to numbers that are meaningless to most folks really quickly.

How fast would space craft need to move for Solar System travel to be like modern world travel?

Well, let's see. If you can go 0.1c (one-tenth light speed - fast enough that relativistic effects start becoming noticeable, but still easily comprehensible), you can go from the Sun to Earth in about 80 minutes. You could go from the Earth to Mars in between 40 minutes and 2 hours (depending on orbital positions). You could go from the Earth to Saturn in something between 11 and 14 hours (again, depending on orbital positions). Getting out to Neptune from the inner solar system would take 40 hours or so. Getting out to Pluto from here might take up to 64 hours.

How fast would space craft need to move for Milky Way travel to be like modern world travel?

The Milky Way has a diameter of roughly 100,000 light years. If you want to be able to get anywhere in the galaxy in a matter of a day or so, you need to be able to go... 30 million times the speed of light? That's 300 million times faster than you need to do the same thing in the solar system - that gives you an idea of the differences in scale.

How fast would space craft need to move for intergalactic travel to be like modern intercontinental travel?

The nearest galaxy is 2.5 million light years away. To get there in a day, you need to be able to go 900 million times the speed of light or so? Call it a round billion times lightspeed. And that's just to reach the nearest galaxy.

The visible universe has a radius of 46.5 billion light years. To reach the edge of it in one year, you need to be able to go 46.5 billion times the speed of light. To get to the edge of it in a day, you're talking 17 trillion times lightspeed.

 

[freyar]

Umbran's got that covered, even leaving aside the light-speed limit in normal physics (never mind the neutrinos for now, since there's most likely a problem with that experiment somewhere).

Just in terms of getting around earth, it doesn't have to be an area in tall, remote mountains that's difficult to get to. I was invited to a conference in Italy that would have taken about 2 days solid travel to reach from Canada --- just no nearby airport.

 

[Bullgrit]

So traveling beyond our planetary system really won't be a matter of speed, but probably of finding some loophole in spacetime to slip through?

The visible universe has a radius of 46.5 billion light years.

This brings up related questions.

Isn't the universe estimated to be less than 14 billion years old? How can we have a larger visible radius than that? And how can the universe be bigger in lightyears than its age in years?

Bullgrit

 

[Dioltach]

The Lost Fleet series (The Lost Fleet - Wikipedia, the free encyclopedia) gives a pretty convincing description of the duration of space travel. Even in-system, at 0.1 times the speed of light, manouvering takes days. Travel between systems uses an extradimensional system of hubs, but even then can take weeks.

I'll leave you with Douglas Adams's description of space, which really says all you need to know:

"Space," [the Guide] says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen..."

 

[jonesy]

Isn't the universe estimated to be less than 14 billion years old? How can we have a larger visible radius than that? And how can the universe be bigger in lightyears than its age in years?

Space itself is expanding.

 

[Bullgrit]

Space itself is expanding.

Yes, I know. But faster than light speed?

Bullgrit

 

[Umbran]

So traveling beyond our planetary system really won't be a matter of speed, but probably of finding some loophole in spacetime to slip through?

Traveling outside our solar system as if it were like on our planet today? Yes, that requires a fundamental change in our understanding of physics. There's still ways to colonize while limited by lightspeed, but going to another star for a vacation's not going to happen.

Traveling outside our galaxy is probably not possible at all without some new physics.

Isn't the universe estimated to be less than 14 billion years old?

Yep.

How can we have a larger visible radius than that?

The distances to those outer objects are generally given as they are now, not as they were when they emitted light we can see. They were 14 billion light years or so away when they emitted light we can now see, but have moved since then.

And how can the universe be bigger in lightyears than its age in years?

By not being a flat. Locally, near us, spacetime looks flat. On cosmological scales it isn't. The result is that if we look at it as if it is flat, then the relative speeds of objects over the life of the Universe don't make much sense.

A little later, I'll try to write up a description that might make sense of it.

 

[Umbran]

Yes, I know. But faster than light speed?

No. Because "space" is not a moving, physical object that is bound by lightspeed. As I noted, I'll try for a description that'll make a bit more sense of it later today.

 

[jonesy]

Yes, I know. But faster than light speed?

If I put two dots on a balloon, and then measure the speed of light between them, and then put more air in the balloon so that the dots are farther apart, and do the same measurement again, would you assume that light was now travelling slower?