Aliens: Yes Or No?

[Ryujin]

It may turn out that despite there being theoretical ways to effectively bypass the galactic speed limit and travel at superlumial speeds, there is actually no practical way to do so. We may never meet an alien, except possibly via Interplanetary Zoom meeting.

 

[CleverNickName]

At near-light speeds, the mass of the particle becomes the limiting factor. Light travels faster than all other known particles (or energy waves, depending on which equation is examining it) because it has the lowest mass of all other observable forms of matter (or energy, depending.) If it had less mass, it would travel faster.

Mathematically speaking: in our universe, the speed of light is not just a constant--it's a limit.

Is it possible for there to be other forms of matter or energy with lower mass than light? It's hard to say. They would be moving so fast that they would be unobservable by anything made of matter or energy. They would pass right through other particles and energy fields so suddenly that they would have no influence whatsoever. Cameras couldn't photograph them, our lenses couldn't see them, our radios couldn't hear them, they couldn't affect us or influence anything in any way. And at that point, do they really even exist?

 

[briggart]

We have crashed so many probes on Mars. The amount of stuff that has to go right for interplanetary travel -- to say nothing of interstellar travel -- is impossible to overstate.

Weird thing is, we haven't actually (unintentionally) crashed that many probes on Mars. Lots of those failed before starting the final descent: some did not even leave Earth's gravity well, some were lost in transit and some others did not properly perform the final orbital adjustment for atmospheric entry and just flew by. And some of those who successfully landed had some other critical failure.

On the other hand, we now have a Tesla commuting between Earth and Mars.

 

[Ryujin]

Weird thing is, we haven't actually (unintentionally) crashed that many probes on Mars. Lots of those failed before starting the final descent: some did not even leave Earth's gravity well, some were lost in transit and some others did not properly perform the final orbital adjustment for atmospheric entry and just flew by. And some of those who successfully landed had some other critical failure.

On the other hand, we now have a Tesla commuting between Earth and Mars.

I remain unimpressed, until it actually lands.

 

[MarkB]

Weird thing is, we haven't actually (unintentionally) crashed that many probes on Mars. Lots of those failed before starting the final descent: some did not even leave Earth's gravity well, some were lost in transit and some others did not properly perform the final orbital adjustment for atmospheric entry and just flew by. And some of those who successfully landed had some other critical failure.

That doesn't exactly speak to a more optimistic view of our success rate at interplanetary travel.

Did remind me of this old video, though.

 

[Clint_L]

It sort of bugs me when questions like this, that can only have probabilistic answers, are framed in absolutes. Yes, given the immense scale of the known universe, there is probably other intelligent life somewhere in it. Probably a lot of it.

Given a complete lack of evidence to the contrary, no, intelligent life has probably never contacted us or been here, at least in recorded history.

 

[ichabod]

It sort of bugs me when questions like this, that can only have probabilistic answers, are framed in absolutes. Yes, given the immense scale of the known universe, there is probably other intelligent life somewhere in it. Probably a lot of it.

I would even argue with the probabilistic statement. It requires a lower bound on the probability of life, and I don't see any evidence for that. If P is the number of planets in the universe, it doesn't matter how big P is, the probability of intelligent life on a given planet could still be 1/P. I really think we just have no clue whether or not there is intelligent life out there.

 

[Parmandur]

I would even argue with the probabilistic statement. It requires a lower bound on the probability of life, and I don't see any evidence for that. If P is the number of planets in the universe, it doesn't matter how big P is, the probability of intelligent life on a given planet could still be 1/P. I really think we just have no clue whether or not there is intelligent life out there.

Exactly, and the Drake Equation has a number of other factors that could reduce the final answer to "1." We don't even know ow enough to say what is probable or not: ao, for practical purposes, the null hypothesis remains the likely answer, strictly speaking, until further evidence comes to light.

 

[Clint_L]

I think the scales involved here are so vast that it is best to be prudent, and so it seems to me that on this particular question the null hypothesis is very presumptuous.

 

[Parmandur]

I think the scales involved here are so vast that it is best to be prudent, and so it seems to me that on this particular question the null hypothesis is very presumptuous.

The prudent choice is to be agnostic on the question and keep collecting data...but the null hypothesis is just as likely as there being anything there, based on our current knowledge. We know we exist, but we don't know enough about the conditions needed for that to say if they are common or absolutely unique. So, until we have further evidence...