If Aliens Existed, Would Inter-Galactic Travel be Possible?

[bballwaterboy]

Is the distance too far and/or the trip too dangerous for inter-galactic space travel by aliens wanting to reach Earth?

 

[Doug Huffman]

The nearest star is four lightyears away. Our galactic center is 0.027 million lightyears away. All of the galaxy-like objects within a million lightyears are considered satellites of the Milky Way, our galaxy.

In other words, it will take about a million years at lightspeed to travel between the Milky Way and the nearest distinct alien galaxy.

I am amused by my favorite lecturer trying to speak of large numbers like the size of our universe or its population without using the word infinite but still respect the magnitude. 10^500 is a long way from infinity.

 

[enorbet]

Without some FTL travel, probably meaning space-folding, or something we have yet to even have a clue about (not even fit for speculation) since nothing can go faster than light, they surely can't. In another thread there is a discussion that puts this into focus. Radio broadcast waves have been traveling omnidirectionaly at light speed for 100 years so there is a sphere of radio 200 light years in diameter. There is a link in that thread that shows graphically how a 200 light year bubble looks in our "liitle arm" of the galaxy. It's rather humbling. It's a REALLY big place.

 

[Doug Huffman]

Is the distance too far and/or the trip too dangerous for inter-galactic space travel by aliens wanting to reach Earth?

Let's consider the second clause of OPie's question; what possible dangers are there in inter-galactic space - beyond boredom?

There is so much nothing that the mean free path of a photon is 10 billion lightyears and occasionally just a few hydrogen atoms per cubic meter. There is a lot of nothing to be dangerous.

 

[iknowsigularity]

Let's consider the second clause of OPie's question; what possible dangers are there in inter-galactic space - beyond boredom?

There is so much nothing that the mean free path of a photon is 10 billion lightyears and occasionally just a few hydrogen atoms per cubic meter. There is a lot of nothing to be dangerous.

I feel since we know so little of dark energy/matter there could potentially be unsuspected dangers in inter-galactic travel.

 

[Doug Huffman]

Dark matter was found as the cause of anomalous motions of galaxies and apparently occurs in conjunction with them, as 'halos' - and not in inter-galactic space.

Weakly Interacting Massive Particles - WIMPS - are a suspected dark matter, the weakly interacting kind'a militates against their hazard.

 

[SteamKing]

Even if interstellar travel existed, it would probably be easier to find one particular grain of sand in the Sahara Desert than to locate the Earth from inside the Milky Way galaxy, let alone from outside the galaxy.

It's not like there are a bunch of Burma Shave signs in outer space pointing the way here. Even if alien civilizations were listening for radio transmissions, these could only be picked up from within 125 light years of earth, which is well within the Milky Way.

 

[iknowsigularity]

Dark matter was found as the cause of anomalous motions of galaxies and apparently occurs in conjunction with them, as 'halos' - and not in inter-galactic space.

Weakly Interacting Massive Particles - WIMPS - are a suspected dark matter, the weakly interacting kind'a militates against their hazard.

i would argue that more of "empty space" is fill with low levels of dark matter rather than empty void.

 

[phinds]

Is the distance too far and/or the trip too dangerous for inter-galactic space travel by aliens wanting to reach Earth?

How can you possibly image that they would "want to reach Earth"? Earth to someone in another galaxy is some utterly insignificant speck of dust WAY too far away to even THINK about having any reason to bother with and also it is just one of billions of such insignificant specks of dust far away from them.

 

[iknowsigularity]

Even if interstellar travel existed, it would probably be easier to find one particular grain of sand in the Sahara Desert than to locate the Earth from inside the Milky Way galaxy, let alone from outside the galaxy.

It's not like there are a bunch of Burma Shave signs in outer space pointing the way here. Even if alien civilizations were listening for radio transmissions, these could only be picked up from within 125 light years of earth, which is well within the Milky Way.

Exactly, this with a lot of other factors would add to the danger involved with inter-galactic travel.
Getting lost in Inter-Galactic space would suck. Sure you could find you way to the nearest galaxy, but what would you do from there. Stop and ask for directions?

 

[SteamKing]

I don't think you have to worry too much about IG travel. Getting from one star to the next inside a galaxy is daunting enough.

 

[Danger]

i would argue that more of "empty space" is fill with low levels of dark matter rather than empty void.

Has it ever crossed your mind that you arguing against reality doesn't change it?

 

[iknowsigularity]

Has it ever crossed your mind that you arguing against reality doesn't change it?

Its a physics forum, not youtube comments. Try replying with something of content.

 

[Danger]

Its a physics forum, not youtube comments. Try replying with something of content.

We have done nothing but reply with content. You are the one who came here uninvited and is unwilling to accept input from people who clearly know far more about the subject than you do.
You are certainly not being of any help to the OP.

 

[iknowsigularity]

We have done nothing but reply with content. You are the one who came here uninvited and is unwilling to accept input from people who clearly know far more about the subject than you do.
You are certainly not being of any help to the OP.

ok fair enough, my apologies.

 

[Danger]

Accepted.

 

[tionis]

Is the distance too far and/or the trip too dangerous for inter-galactic space travel by aliens wanting to reach Earth?

They evolved and now travel through the bulk. Just like we are going to evolve into bulk beings. I saw it in a movie recently.

 

[phinds]

They evolved and now travel through the bulk. Just like we are going to evolve into bulk beings. I saw it in a movie recently.

This is blather and does not belong in a serious discussion. If you were trying to be funny, I didn't get it.

 

[tionis]

This is blather and does not belong in a serious discussion. If you were trying to be funny, I didn't get it.

How can you possibly image that they would "want to reach Earth"? Earth to someone in another galaxy is some utterly insignificant speck of dust WAY too far away to even THINK about having any reason to bother with and also it is just one of billions of such insignificant specks of dust far away from them.

Judging by your previous reply to the OP, you could have fooled me that you actually took the the discussion as ''serious.'' :p

 

[phinds]

Judging by your previous reply to the OP, you could have fooled me that you actually took the the discussion as ''serious.'' :p

I don't follow you at all. My response was completely serious.

 

[tionis]

I don't follow you at all. My response was completely serious.

So was mine. And I have a caltech scientist and a billion lines of code that back me up.

 

[phinds]

So was mine. And I have a caltech scientist and a billion lines of code that back me up.

? You have a scientist to back up the statement "They evolved and now travel through the bulk. Just like we are going to evolve into bulk beings. I saw it in a movie recently."

Well, OK, I guess you COULD have a scientist who could back up the fact that you have been to a movie recently. I doubt the rest.

 

[jollyunclejoe]

These would have to be some sophisticated aliens. If so, it would almost certainly take a very long time. Perhaps millennia between galaxies. I wouldn't think such a long wait would be worth for an alien just to see Earth.

 

[Danger]

Judging by your previous reply to the OP, you could have fooled me that you actually took the the discussion as ''serious.'' :p

Do you have any idea of what the word "Physics" in "Physics Forums" means? Sure, this is a particular small section that deals with SF and even sci-fi and fantasy, but you can't expect anyone who lives here to totally overlook the laws of nature and science that have already been established. In case you were unaware of it... think of every single grain of sand that exists on Earth, in deserts, on the ocean floor, in your cat's bathroom, wherever. That number does not even come close to how many stars there are in the observable universe. Do you ever look up in the sky, pick out a spot that has no visible star because the one in that direction is too far away to be seen, and think, "Gee, I'd really like to go there"?

 

[Evo]

This thread is completely against the forum rules. Those of you that wish to discuss "interstellar" should do so in that thread. https://www.physicsforums.com/threads/interstellar-spectacularly-stupid-movie.780388/