If You Flew in a Random Direction into Space, Would You Almost Certainly Run into a Star?

Question

If you drew a random line (vector) from earth, would the vector almost certainly hit a star?

Or would the vector most likely continue to the edge of the known universe (assume "Big Bang") without touching a star?

Assume that your direction isn't affected by gravity. Assume the stars don't move from their current locations.

Answer 1

No, you would probably not run into anything at all!

Cool question. This question has been considered by astronomers for a long time, and was once called "Olbers' Paradox." If the universe was infinite in size, and had existed forever, and had the same density everywhere, then yes: you'd eventually hit a star. But that would also mean that light from that star would eventually hit the Earth. Which means that everyplace you looked in the sky would have the light of a star shining back at you! In that case, the sky would always be as bright as the surface of a star, day or night.

Obviously, the sky isn't as bright as the surface of a star, and in fact it's pretty dark at night. That is what first made people wonder if maybe the universe wasn't infinite, or wasn't infinitely old, or wasn't of uniform density.

If you travel at the speed of light, then pointing in a random direction and firing a photon away would result in the photon zooming away from Earth, probably not hitting anything at all, and ultimately (billions of years from now) getting stranded in the middle of nowhere as the constant expansion of space meant that any interesting galactic clusters would be incredibly far apart and nearly impossible to hit.

If you allow yourself to travel instantaneously (draw a line through the frozen spacetime of the universe) then another poster is right: you might end up looping back, and in that case you'd probably hit something. The universe probably (we're not sure, but *probably*) curves back on itself, so you'd keep looping and looping until eventually you hit something, however unlikely that was.

But for anything we can do or measure physically (travelling at the speed of light or less), a particle fired in a random direction will probably never hit anything--that's why the night sky is dark.

Answer 2

It depends how you consider the Universe. Right now it seems likely that the Universe's space is wrapped, so if you kept on moving in one direction long enough you would arrive back where you started. If this is true, then chances are any individual line would not hit a star before it came back to its starting point (it would trace a hypercircular path across the Universe without intersecting a star). Of course in real life things might be a little more complicated than this, but in any case the fact is that very, very little of the Universe is inside a star. To give you an idea of just how little, consider that the Sun only takes up that much of the sky, and still manages to drown out the light from all the other stars in the Universe by several orders of magnitude (the difference in light between day and night). In fact, if your line DID hit a star, chances are something like over 1000 to 1 that that star would be the Sun because it has a much greater angular size (again, proved by the relative light test).

Answer 3

The question is not limited in time and space. We dont know exaclty where is the edge of the universe. We dont know exaclty the position of each star. So given these assumptions then i suppose that it is possible that you will hit a star somewhere at some point in time. Look at the sky and you see light everywhere. It means there is a star in that direction. If you dont see a light at a particular point in space it doesnt mean that there is no star there. It could mean that it so far away that the light hasnt reached your eye yet. If you dont want to take chances if you do fly, then follow the example of the guys in Battlestar Galactica. They do several jumps in known space going to their destination. This is to avoid hitting any object or a a star for that matter that might be in their path. Absurd? Think about it. It makes sense to me.

Answer 4

You'd likely not hit a star since the universe is so huge and stars make up a pretty small percentage of it. Mind you, if that random direction happened to be toward the center of a galaxy then the chances of hitting a star increase but still, two massive galaxies colliding usually just pass through each other. Keep in mind that if our sun were the size of a grain of salt then the nearest star, Proxima Centauri, is FOUR MILES away. Given that, what are the chances of hitting another star?

Answer 5

well if you think of how random space is and how often metorites hit the earths atomosphere (shooting stars) then it should be abosoloutly possible to run into a star, providing you have enough time plus the energy to go that far.

Answer 6

Vanishingly small. The amount of space between stars, even when they're close together, is huge (to put it mildly). If you happen to be heading for the core of a globular cluster or central bulge of a galaxy, your chances increase slightly.

Answer 7

yes, the universe is so huge and there are so many stars and planets that eventually there will be a celestial body occupying a line of space
0 is space, x is a celestial body

00000
00000
000x0
00x00
xx00x
x0x0x0

see, there will be a star or planet in a line prolly

Answer 8

If it were true, then we would see much more light than we do from distant galaxies - I would say no - at least out to the observable universe (14B light years or so...)

Answer 9

almost would not, bcoz the distance between any two stars are so long. even the light would took years for this range.

Answer 10

The odds would be tremendously low. Could it happen, yes, anything's possible, you could even run into Sol, if it were completely at random. But if you missed our sun, then the odds are virtually nil.