It's true that there could be fairly nearby civilizations,within robotic traveling-distance, that just aren't interested in it.

But, for a spacefaring civilization to not care, or having a prime-directive against intervention--I feel that any technically-advanced civilization would also be morally-advanced, and would want to help us. ...because it would be grossly obvious to anyone, even aliens, that we're badly in need of help here.

If I find an insect drowning in water, I rescue it, fish it out. Likewise, any advanced civilization that knew about us would help us--bring us the help, the babysitting, that we obviously so badly need.

So I'd rather that you be right about there being nearby life.

Our society very badly needs babysitting, interstellar intervention.

So it would be better if you were right.

Michael Ossipoff

I've done a little web research on the subject of physical infinity. I have come to a definitive conclusion on the matter, definitive in the sense that I have solid support for my point of view the next time this comes up online.

I looked at several popularized article based on a Google search for "physical infinity."

Many of the articles were very lightweight and uninformed. A typical example talked about the achievements of Cantor, then invoked the Hilbert hotel argument to show how strange infinity is, claimed that there are infinitesimals in calculus, then started waving their hands at physics.

So many of the articles were like this that I realized that most of the people writing popularized articles about infinity don't know the first thing about it. They've heard of Cantor and they've heard about the Hilbert hotel, a story that Hilbert told once to a public audience, and never mentioned again in his entire career. Hilbert's hotel is like the bowling ball and rubber sheet model of gravity. It's not literally true. It's a popularization. A fable for the tourists. Not to be taken as a substitute for actual math or physics.

So people hear about Cantor and about the Hilbert hotel and they think they understand mathematical infinity and set theory and they simply don't. And they transmit their misunderstandings to a new generation of credulous readers.

Fortunately after wading through all this garbage I hit the mothorlode. I found Max Tegmark's on-the-record opinion.

Max Tegmark says there are no physical infinities. And that infinity is a "bad idea that needs to be banished from physics."


I'd like to pull a few quotes from his article. But it's a short article and well worth reading in its entirety.

http://blogs.discovermagazine.com/crux/2015/02/20/infinity-ruining-physics/

By the way Tegmark explicitly says that the infinities in the multiverse argument are meaningless. That supports my position in the multiverse thread where people were arguing that there are literally infinitely many universes. Max Tegmark says you're wrong.

Herewith some quotes.

Physics is all about predicting the future from the past, but inflation seems to sabotage this. When we try to predict the probability that something particular will happen, inflation always gives the same useless answer: infinity divided by infinity. The problem is that whatever experiment you make, inflation predicts there will be infinitely many copies of you, far away in our infinite space, obtaining each physically possible outcome; and despite years of teeth-grinding in the cosmology community, no consensus has emerged on how to extract sensible answers from these infinities. So, strictly speaking, we physicists can no longer predict anything at all! — Tegmark

Infinity Doesn’t Exist — Tegmark

Consider, for example, the air in front of you. Keeping track of the positions and speeds of octillions of atoms would be hopelessly complicated. But if you ignore the fact that air is made of atoms and instead approximate it as a continuum—a smooth substance that has a density, pressure, and velocity at each point—you’ll find that this idealized air obeys a beautifully simple equation explaining almost everything we care about: how to build airplanes, how we hear them with sound waves, how to make weather forecasts, and so forth. Yet despite all that convenience, air of course isn’t truly continuous. I think it’s the same way for space, time, and all the other building blocks of our physical world. — Tegmark

Not only do we lack evidence for the infinite but we don’t need the infinite to do physics. Our best computer simulations, accurately describing everything from the formation of galaxies to tomorrow’s weather to the masses of elementary particles, use only finite computer resources by treating everything as finite. So if we can do without infinity to figure out what happens next, surely nature can, too—in a way that’s more deep and elegant than the hacks we use for our computer simulations. — Tegmark

Our challenge as physicists is to discover this elegant way and the infinity-free equations describing it—the true laws of physics. To start this search in earnest, we need to question infinity. I’m betting that we also need to let go of it. — Tegmark

Well folks there you have it. Tegmark doesn't think infinities are real.

That's good enough for me. I suspect the link to this article will save me a lot of trouble going forward when these convos come up.

But, for a spacefaring civilization to not care, or having a prime-directive against intervention--I feel that any technically-advanced civilization would also be morally-advanced, and would want to help us. ...because it would be grossly obvious to anyone, even aliens, that we're badly in need of help here. — Michael Ossipoff

I don't think there's any justification for saying what an alien civilization would do if they tripped over us in their travels. I also don't share your desire for them to solve our problems for us. Seems to me they are as likely to make things worse as better.

it's a question of scale isn't it? "Large", "small" are relative terms and will be different for different observers. For an ant a kilometer is "huge" but for us it's a 1 hour walk. Isn't this why scientists scale down cosmic and microscopic distances to more intuitive measurements?

Have you watched Men In Black. Part 1 ends with a very interesting viewpoint - shows how truly big the universe might be.

One picture can save a thousand words. One movie can...

One picture can save a thousand words. One movie can... — TheMadFool

I also don't share your desire for them to solve our problems for us. Seems to me they are as likely to make things worse as better. — T Clark

It would be great if we had a chance to find out, because the situation is otherwise obviously quite hopeless for society and planet. (Not that I expect that help, for the reasons that I described).

I'd expect advanced civilizations to be morally advanced too. I mentioned how often a person will rescue a drowning insect. Some people expect aliens to be monsters because that's all they're used to, in our society. It's natural to expect aliens to be like the genuine villains here, but there isn't really a reason to expect that.

Michael Ossipoff

Tegmark used to say that it the universe was likely infinite. I myself don't claim to have information about that.

Maybe Tegmark has good justification, now, for saying that it isn't.

You mentioned a mathematical argument about that. It was an area that isn't familiar to me, so I can't say I disagree.

So maybe there's some reason why it can be known that the universe isn't infinite, but I don't know about it.

Michael Ossipoff

Maybe Tegmark has good justification, now, for saying that it isn't. — Michael Ossipoff

The rightness or wrongness of Tegmark's idea doesn't matter so much as the fact that I can add, "and Tegmark agrees with me!" when I argue the same point. It doesn't matter whether Tegmark and I are right or wrong. How can anyone really know? But at least I can stand my ground on this particular point with greater rhetorical force.

I seem to remember from Zen and the Art of Motorcycle Maintenance that rhetoric is regarded as one of the lesser arts. Reasoning for the purpose of winning an argument is inferior to reasoning for the purpose of discovering truth. If I understood all that correctly.

I seem to remember from Zen and the Art of Motorcycle Maintenance that rhetoric is regarded as one of the lesser arts. Reasoning for the purpose of winning an argument is inferior to reasoning for the purpose of discovering truth. If I understood all that correctly. — fishfry

I don't remember if it was in ZAMM, but it's true. On the other hand, when it's appropriate for the discussion or if I'm in the mood, I'm willing to take the position that truth is what you can convince people of.

Of course I've got Tegmark agreeing with me too, about something else--that this universe consists of abstract facts, along with infinitely-many such possibility-worlds. (It's in this physical world that he's saying that there aren't infinities).

Whether this universe is infinite or not is a detail of the setting of our life-experience-stories. The remarkable thing is that this life started.

I seem to remember from Zen and the Art of Motorcycle Maintenance that rhetoric is regarded as one of the lesser arts. Reasoning for the purpose of winning an argument is inferior to reasoning for the purpose of discovering truth. If I understood all that correctly. — fishfry

I'm sure that's right. i hadn't heard it, and the matter hadn't occurred to me like that, but now that you mention it, of course it's true. There's too much argumentativeness here, where discussion should be civil and just have the goal of collectively finding out.

Michael Ossipoff

About whether the mass-density in a black hole is infinite, here's a quote from the Internet. Of course I should state the source of the quote, and it's sloppy not to. It's just that, when that occurred to me, I was too lazy to go back and write down the source.

Here's the quote:

It will continue to collapse, and the gravity increases. Smaller, smaller… and when I was a kid I always read that it collapses all the way down to a geometric dot, an object with no dimensions at all. That really bugged me, as you can imagine… as well it should. Because it’s wrong.

At some point, the collapsing core will be smaller than an atom, smaller than a nucleus, smaller than an electron. It’ll eventually reach a size called the Planck Length, a unit so small that quantum mechanics rules it with an iron fist. A Planck Length is a kind of quantum size limit: if an object gets smaller than this, we literally cannot know much about it with any certainty. The actual physics is complicated, but pretty much when the collapsing core hits this size, even if we could somehow pierce the event horizon, we couldn’t measure its real size. In fact, the term "real size" doesn’t really mean anything at this kind of scale. If the Universe itself prevents you from measuring it, you might as well say the term has no meaning.

And how small is a Planck Length? Teeny tiny: about 10-35 meters. That’s one one-hundred quintillionth the size of a proton.

[endquote]

Michael Ossipoff

I know the number of permutations for a deck of 52 cards is straightforward enough. It is 52!, or 52 factorial. There are 52 possibilities for the first card, since there are 52 cards to select from. For each of these initial 52 choices, there are another 51 possibilities for the second spot, so the number of combinations for the first two cards is 52 x 51, and then for each of these possibilities we have 50 for the third spot, thus, it should be easy to see the pattern here, 52 x 51 x 50 x 49 x ... x 1, which is the same as 52!. However, I have no idea about the number of grains of sand we have.