Do you believe we are alone in the universe?

The universe is far, far, far too big and ancient a place to reasonably rule out life elsewhere. Even if the galaxy is currently lacking intelligent life other than our own (and I'm not convinced it is - our expectations of what intelligent life should be doing with itself is, obviously, prejudiced toward our own ideals), I don't think it was nor will be. I'm also much more optimistic about FTL.

 

[Zardnaar]

Jeez, guys, what’s with all the hostility? It’s nearly Christmas! It’s a thread about aliens!

It started to go downhill when people started declaring absolutes around FTL travel. Came across as hostile as in "you're wrong nya nya nya" IMHO.

 

[Maxperson]

You were referring to new science of the form, "everything we know is wrong". My point is that that doesn't really happen. In modern science, the things we know... we know. We observe them up, down, and crossways. We measure and remeasure and confirm. New science can't change what we have already seen! Any new understanding of the universe must be consistent with old understanding. F'rex: We have observed gravity's scaling with the square of distance on the scale of mountains to the scale of galactic clusters. Any new idea of gravity must be consistent with those observations, or the new idea of gravity is clearly wrong.

Imagine you live on the island that just killed that missionary. You have virtually no contact with the outside world, but you see airplanes flying all the time. Your theory is that the gods keep these sky canoes aloft and so that they never fall from the sky. Now say they end the restrictions on contact with this tribe and you learn a few years from now what gravity is, what airplanes are, and how planes are kept aloft. The new information is consistent with what you knew, but what you knew would still be completely wrong.

We could be completely wrong about what gravity is and how it truly works, even though the new knowledge is consistent with what you observed. Hell, we don't actually know how it works. We just know it does. We also don't know if there are conditions under which it might not work at all, or work completely differently that we just haven't observed yet.

So, any form of FTL that we get must still be consistent with everything else we have ever observed. And that puts some very restrictive boundaries on it if it does exist.

Possibly. Just because we haven't observed something, doesn't mean that there aren't rare conditions under which those boundaries aren't as restrictive or even restrictive at all. Or for that matter, if the restrictions we observe apply to everything that happens naturally, but don't apply to X, Y and Z unnatural applications that intelligent beings could come up with.

Just look at what we've done so far. Natural restrictions kept mankind on the planet and would continue to keep mankind on the planet until we or the planet ended. However, we invented an unnatural method to propel us off the planet and visit the moon. We went around the restrictions on us by applying other things in a way that doesn't occur naturally. We could wait from the beginning of the universe until the end and nature wouldn't provide us with rockets and space suits to make the trip. There could be work-arounds on the limit against traveling faster than the speed of light. We don't know yet.

 

[Maxperson]

https://phys.org/news/2018-12-universe-theory-percent-cosmos.html

This does change the understanding of physics.

Man. That article would have been so much better if the physicist was named Dr. Farnsworth.

 

[dragoner]

Man. That article would have been so much better if the physicist was named Dr. Farnsworth.

Though it's from Oxford University, not New New York.

The comments below it are great.

 

[Umbran]

https://phys.org/news/2018-12-universe-theory-percent-cosmos.html

This does change the understanding of physics.

It changes nothing, yet. It is an hypothesis.

And not a new one. This is an interpretation of the cosmological constant in Einstein's General Relativity. Anyone who has studied Einstein's work in detail knows about it, and how with varying values it leads to a universe that eventually collapses in on itself, is static (never expanding or contracting) or ever-expanding.

The real issue with it (that they do mention) is simple - used in this way, it calls for a continuous and eternal (and, depending on your choices, ever-increasing) creation of negative mass out of nothing.

And that... seems kind of a hack. It looks tidy, until you realize that an eternal fire hose of negative mass that supports it is just assumed to exist.

 

[Maxperson]

It changes nothing, yet. It is an hypothesis.

And not a new one. This is an interpretation of the cosmological constant in Einstein's General Relativity. Anyone who has studied Einstein's work in detail knows about it, and how with varying values it leads to a universe that eventually collapses in on itself, is static (never expanding or contracting) or ever-expanding.

The real issue with it (that they do mention) is simple - used in this way, it calls for a continuous and eternal (and, depending on your choices, ever-increasing) creation of negative mass out of nothing.

And that... seems kind of a hack. It looks tidy, until you realize that an eternal fire hose of negative mass that supports it is just assumed to exist.

That's how I view dark energy and dark matter as well.

 

[dragoner]

It changes nothing, yet. It is an hypothesis.

And not a new one. This is an interpretation of the cosmological constant in Einstein's General Relativity. Anyone who has studied Einstein's work in detail knows about it, and how with varying values it leads to a universe that eventually collapses in on itself, is static (never expanding or contracting) or ever-expanding.

The real issue with it (that they do mention) is simple - used in this way, it calls for a continuous and eternal (and, depending on your choices, ever-increasing) creation of negative mass out of nothing.

And that... seems kind of a hack. It looks tidy, until you realize that an eternal fire hose of negative mass that supports it is just assumed to exist.

I agree with you 100%.

Mostly it just something happy to dream about while dealing with relatives over Christmas.

 

[Umbran]

That's how I view dark energy and dark matter as well.

If we look at pretty much any galaxy, we can see (via doppler shift of light from stars) how fast the stars in it are orbiting the galaxy's center. They are pretty much all orbiting too fast. When you do the math, they are moving too fast in the exact way you'd expect if the galaxy was far heavier than the sum of all mass of all the stars we can see.

In this situation, is it "a hack" to guess that, when it moves as if there's matter you don't see, that there probably *is* some matter we don't see?

And, in case you are thinking this, no, the physics community didn't just say, "Hey, there's dark matter there," and move on. They hypothesized that it is there, and have been looking for exactly what it was ever since. As well as looking at other explanations, like modifications to gravity that still fit what we observe in, say, the movements of planets in our Solar System - but none of those other options have worked out yet. So, we have a leading (and simplest) hypothesis.

That's all "dark matter" is - a leading hypothesis.

 

[dragoner]

It looks tidy...

The article was a little more glib than the pdf from arxiv, and it being Oxford, one hopes with a little more rigor than a random pop sci article. Just saying it's only a sign change, is too glib in that plugging a sign change into equations can change everything, so it's not "just a sign change". I also found the creation of negative mass curious; and ultimately this looks to be grant writing, more than a complete theory.

 

[Maxperson]

If we look at pretty much any galaxy, we can see (via doppler shift of light from stars) how fast the stars in it are orbiting the galaxy's center. They are pretty much all orbiting too fast. When you do the math, they are moving too fast in the exact way you'd expect if the galaxy was far heavier than the sum of all mass of all the stars we can see.

In this situation, is it "a hack" to guess that, when it moves as if there's matter you don't see, that there probably *is* some matter we don't see?

Yes, it's still a hack. There could be other forces other than gravity or matter that play into the acceleration. Or maybe there is enough mass in the universe that we can see that accounts for it, but there are aspects of gravity that we just don't know about yet.

And, in case you are thinking this, no, the physics community didn't just say, "Hey, there's dark matter there," and move on. They hypothesized that it is there, and have been looking for exactly what it was ever since. As well as looking at other explanations, like modifications to gravity that still fit what we observe in, say, the movements of planets in our Solar System - but none of those other options have worked out yet. So, we have a leading (and simplest) hypothesis.

That's all "dark matter" is - a leading hypothesis.

No, I wasn't think they just put dark matter/energy forth and then move on. It is, however, just something unseen and undetectable that they stuck in to explain something we are observing. We could just as easily sub in God and look for his existence as the reason for this. That's why it feels like a hack to me.