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What Is Space?

nautil.us

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Re: What Is Space?

#51

Post by graycat »

cyphar wrote: post #30
graycat wrote: post #22

Do we know enough yet to have some good guesses about (1) the purpose of the universe, https://news.ycombinator.com/item?id=14570170 (2) the end of the universe, (A) big expansion and cool down to nothing, (B) no more expansion and cool down to nothing, (C) contraction back to another big bang, (D) something else very different?

> (1) the purpose of the universe, This question is far more philisophical than anything. Personally I subscribe to Camus' Absurdism[1] -- that our yearning for meaning and purpose is ironic given how uncaring and lacking in meaning our universe is. > (2) the end of the universe There are several theories[2], but from my understanding we need to better understand "dark matter" and "dark energy" (scare quotes because…

For my first question, I was wondering if by now we had enough information to make a guess that is not just philosophical.

Re: What Is Space?

#52

Post by TheSpiceIsLife »

kobeya wrote: post #47
anonymoose111 wrote: post #38

Earlier quoted context omitted.

google interviews try to gauge how smart you are, not how well you can program

I fail to see how someone who is not a domain expert on the nature of space-time asking someone else who is not a domain expert can result in a reliable determination of how smart either person is. To be clear, I don't think the correct answer of "I don't know, but I'll do a review of the literature and see what the scientific consensus is" is what the interviewer was hoping for, which is my contention.

You can have it both ways. I'd probably say something like "That's not my field of expertise, though if you'd like me to speculate I'd be glad to."

Re: What Is Space?

#53

Post by sillysaurus3 »

Razengan wrote: post #16

Some related questions that I don't know where, or how, to ask: - Is there a “quantum” of space? Where/how is location stored? - If electromagnetic repulsion is what makes matter “take space”, and if virtually all macroscopic phenomena are governed by electromagnetism and gravity, then could this reality be said to be “gravelectromagnetic”, and might there be other “dimensions” governed by other forces, like “cones”…

Could gravity be the result of space trying to deflate/return to the pre-Big Bang singularity, kind of like pulling magnets apart? i.e. is gravity the “opposite” of, or a reaction to, “space?”

I may be off the mark with what you believe, but just in case:

It's a common misconception that the big bang originated at a specific point. The big bang seems to have happened everywhere simultaneously, so it wouldn't be true to say that gravity is pulling everything back toward a point of origin.

Here's an excellent video on misconceptions about the universe: https://www.youtube.com/watch?v=XBr4GkRnY04

(Ironically, the video was created because the creator was a scientist, yet they fell into the trap of believing something incorrect to the point of being publicly mistaken about it. The universe is extremely counterintuitive!)

Re: What Is Space?

#54

Post by cyphar »

graycat wrote: post #51
cyphar wrote: post #30

Earlier quoted context omitted.

> (1) the purpose of the universe, This question is far more philisophical than anything. Personally I subscribe to Camus' Absurdism[1] -- that our yearning for meaning and purpose is ironic given how uncaring and lacking in meaning our universe is. > (2) the end of the universe There are several theories[2], but from my understanding we need to better understand "dark matter" and "dark energy" (scare quotes because…

For my first question, I was wondering if by now we had enough information to make a guess that is not just philosophical.

But I don't understand how the question "what is the purpose of X" can be anything but philosophical. Science is primarily concerned with creating models of reality and testing the predictive power of those models. The "purpose" of something is not really a meaningful concept in that context.

... unless by "purpose" you mean cause? As in, what caused our universe to exist? That is also not really a meaningful question, because time began with our universe so it's not clear what the concept of "before our universe" actually would refer to. Physically, I believe the currently popular theory is that the progenitor for our universe was an anti-matter explosion caused by the spontaneous creation of a matter+anti-matter pair (which happens all the time in a perfect vacuum due to Heisenberg's uncertainty relation -- \Delta E \Delta t \ge \hbar/2). There are several unsolved problems with this theory, the biggest one being how does it explain that there is a clear imbalance between the amount of matter and anti-matter in our universe.

Re: What Is Space?

#55

Post by kamaal »

anonymoose111 wrote: post #38
kobeya wrote: post #34

Earlier quoted context omitted.

I went into entrepreneurship because I hate these kinds of interviews. You think a good way to tell whether I'd be good at writing code is my opinion on philosophy outside my domain of expertise?

google interviews try to gauge how smart you are, not how well you can program

If you don't test a candidate how good a programmer they are, you shouldn't be too surprised when you end up hiring a lot of bad programmers.

Re: What Is Space?

#56

Post by graycat »

One of the ones that gets me and may be central to space is the central idea in the Young's double slit experiment, the Michelson-Morley interferometer, the Fabry-Perot interferometer, etc. Indeed, the night I was studying for my final in optics and radiography, I thought of this stuff and never really studied for the exam!

So, just shine a light through a beam splitter. So, ballpark half of the light continues on essentially straight and the other half is deflected 90 degrees.

Such a beam splitter is in the M-M experiment. For the double slit, it divides the beam. For a Fabry-Perot, it ends up making many such splits.

Okay, as we heard from Feynman, we could send just one photon through any of those devices and still get the same interference effects. Feynman also explained that we'd get the same result sending one electron at a time instead of a photon.

So, here, to heck with recombining the beams and getting it to interfere with itself.

Instead, consider just the beam splitter. So, the photon (or electron, neutron, whatever) is a wave function, and after the beam splitter that wave function is in two parts traveling apart, in the case of the photon, if we add a mirror to have the two halves going in opposite directions, at the speed of light.

But such splits of the wave function happen at every window pane, no doubt in every water droplet, etc., that is happen all the time.

And such a wave function doesn't split just once but commonly many times. So, the one, poor photon as one simple wave function is soon in dozens of pieces all moving away from each other usually never to come together again. After a billion years, the pieces are still moving away from each other.

Then, presto, bingo, one part of that wave function enters our telescope and hits our detector. Then all the dozens of pieces of that wave function, scattered across a billion light years, have to disappear, instantly, since with two telescopes we can never get two detections from the one photon.

Well, that's tough to believe.

So, maybe the universe is filled with tiny pieces of wave functions condemned to go on forever. Maybe that's the dark matter?

Re: What Is Space?

#57

Post by kobeya »

TheSpiceIsLife wrote: post #52
kobeya wrote: post #47

Earlier quoted context omitted.

I fail to see how someone who is not a domain expert on the nature of space-time asking someone else who is not a domain expert can result in a reliable determination of how smart either person is. To be clear, I don't think the correct answer of "I don't know, but I'll do a review of the literature and see what the scientific consensus is" is what the interviewer was hoping for, which is my contention.

You can have it both ways. I'd probably say something like "That's not my field of expertise, though if you'd like me to speculate I'd be glad to."

The point is I don't see how speculation about things you know nothing about is supposed to be an accurate gauge of a persons inate intelligence.

Re: What Is Space?

#58

Post by Razengan »

tombh wrote: post #32
Razengan wrote: post #16

Some related questions that I don't know where, or how, to ask: - Is there a “quantum” of space? Where/how is location stored? - If electromagnetic repulsion is what makes matter “take space”, and if virtually all macroscopic phenomena are governed by electromagnetism and gravity, then could this reality be said to be “gravelectromagnetic”, and might there be other “dimensions” governed by other forces, like “cones”…

Nothing to add, I just love where your questions send my mind, thank you.

You may enjoy contemplating a sort of "epiphany" that I had during that usual pondering of imponderables:

That the default or base state of existence may not be nothing, not "not even nothing", but rather Everything. ...

Instead of viewing the origin of all reality/creation as things being added to a canvas of blackness/emptiness/voidness, rather consider that "Existence" may be a subtractive process: akin to holes being poked into a canvas of white, or bubbles in a boiling liquid.

(I mean even before the Big Bang, or the classic "Who Created God"/Prime Mover/First Cause question – humans are given to assuming that the start of anything must be Zero or Nothingness, that the end of everything is Oblivion, and that may not be the case.)

Our existence is a "filter", our perceptions being a very limited subset of everything that's around us, of select wavelengths and frequencies and etc. This entire universe could just be a transient bubble inside a flood of Everythingness. [0]

[0] https://en.wikipedia.org/wiki/False_vacuum#Existential_threa...

Re: What Is Space?

#59

Post by graycat »

cyphar wrote: post #54
graycat wrote: post #51

Earlier quoted context omitted.

For my first question, I was wondering if by now we had enough information to make a guess that is not just philosophical.

But I don't understand how the question "what is the purpose of X" can be anything but philosophical. Science is primarily concerned with creating models of reality and testing the predictive power of those models. The "purpose" of something is not really a meaningful concept in that context. ... unless by "purpose" you mean cause? As in, what caused our universe to exist? That is also not really a meaningful questio…

> But I don't understand how the question "what is the purpose of X" can be anything but philosophical.

Again, my guess is that this depends on how much we know. Or, there about has to be a purpose. And eventually as we learn more there should be some clues about what that purpose is. So I'm wondering if we know that much yet?

A first little clue is the speed of light speed limit that so far seems to say that we are quite isolated from the rest of the universe. So, somehow having us isolated was deliberate. Then, what might be the purpose of having us so isolated?

Then there's the 3 K background radiation. That's one heck of a clue. What might be the reason for giving us such data? To answer, what can we do with it? If we note what we can do with the 3 K data and that seems really special, e.g., we wouldn't be able to do that without the 3 K data, then what is so special we can do with the 3 K data might be a clue for the purpose of letting us have that data.

There's the Heisenberg uncertainty principle. So, it keeps us from being as in an 1890 view of physics, mechanistic. We are stopped at that level by some dice rolling. So, why? When we see how that stops us, we might get a clue of a purpose.

All of that is very thin stuff, but maybe we are on the way to discovering enough to start to conclude what the purpose is.

One point is our existence and our abilities: First cut, how the heck to look at the basic physics and guess the chemistry, then, especially the biology, and, astounding, how the biology developed into us. That's some amazing laws of physics that let that happen, maybe ensured that it would happen. So, what the heck is the purpose of us being here, our existing? That is, we're the most special and amazing thing we know of in the universe. So, if there is a purpose, then it looks like we are a key part of it. So, just what the heck might be what we are to do with our abilities to understand the universe? Then, do we get a hint of the purpose from what we can do? That is, is the purpose the special stuff we can, or will be able, to do? For that if we look ahead, just how much might we be able to do? Build Dyson spheres? Okay, then what would that enable?

We don't see other planets flashing light signals at us from their Dyson spheres. So, why not? Sure: There are other, better forms of long distance communications, and every planet with a Dyson sphere knows this. So, soon we should discover this better means of communications. So, where the heck to look for those better means. Then when we find them, what would that enable us to do in the universe that would be special? Communicate only? Or both communicate and travel? Or, if long distance travel is possible, then why ever bother to travel; just send robots and have them send back the communications so we can view it. Then does that communications give us a clue about a purpose; that is, suppose we could send robots and they would communicate back; what might we discover that begins to suggest a purpose.

Or, generally, as a meta argument, if we find some things that look really, really special that finally, with our development, we can do that seem to impact, explain, discover, reveal the universe, then maybe our doing that is the purpose of the universe.

I fully agree this is very thin stuff. Still I have to suspect that as we learn more, maybe 1 million years from now, we will begin to guess at a purpose.

Or, if there is no purpose, then this is one heck of a big show for nothing!

Re: What Is Space?

#60

Post by anonymoose111 »

kobeya wrote: post #47
anonymoose111 wrote: post #38

Earlier quoted context omitted.

google interviews try to gauge how smart you are, not how well you can program

I fail to see how someone who is not a domain expert on the nature of space-time asking someone else who is not a domain expert can result in a reliable determination of how smart either person is. To be clear, I don't think the correct answer of "I don't know, but I'll do a review of the literature and see what the scientific consensus is" is what the interviewer was hoping for, which is my contention.

that is correct, however that's not exactly what the person in question was looking for while interviewing (not for the other person know have knowledge about the subject) but the ability to be able to understand a concept completely once explained, and work within the rules of the concept. This of course is arbitrary, but not a completely useless question.
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