Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

What Is Space?

nautil.us

Post reply on HN
Print view View original

41–50 of 155 posts

Re: What Is Space?

#41

Post by ChuckMcM »

kobeya wrote: post #34
ChuckMcM wrote: post #29

This continues to be one of my favorite questions. In high school we were creating a vacuum in a bell jar to do the 'drop a feather and drop a weight' experiment and my physics teacher asked it. "So if we didn't have our apparatus in there, and we sucked it dry, what would be in there?" It makes a great interview question because it helps identify people who have a hard time holding an unknown concept in their head a…

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?

   > 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?
It is a way (I'm not sure how to quantify it) to understand if someone can develop something that nobody has ever imagined before. My criteria for evaluating the response was whether or not the candidate could engage with the question. It is something that happened often in my experience at Google, you were presented with an 'impossible' requirements and it was up to you to figure out what you could do about it. If someone was going to say "Well I don't know anything about that, ask someone else." Then the company knew they weren't going to be as successful as we would want them to be.

In the case of the physics student it was just their passion, they had gone way beyond the course work because they were interested in interesting questions.

Re: What Is Space?

#43

Post by baddox »

booleandilemma wrote: post #31
Noxchi wrote: post #8

How fast are you really going? One of the things I've thought about is relatively. Consider a toddler strapped to his car seat in a luxurious BMW cocoon while his father speeds down the autobahn at 200km/h. He calmy drinks from his sippy cup. You're in a passenger jet above him going 700km/hr. You're going 500km/hr faster than him. But how fast are you really going? Consider that the Earth is spinning around the sun…

Relevant quote: "Speed has never killed anyone. Suddenly becoming stationary, that's what gets you". - Jeremy Clarkson

Even that wouldn't hurt you, if every part of you became stationary at the same time.

Re: What Is Space?

#44

Post by ChuckMcM »

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”…

There are a number of interesting places to start, if you want to be traditional start with reading about the Standard Model, if you want to be avant-garde start reading about String Theory :-).

I have come at the question a bit like you have, starting with Faraday and Maxwell for the electromagnetic theory, adding Lorentz and Einstein for the time and space dilation effects of general relativity. And when you start looking at light as an expanding wavefront alternating between a magnetic form and a electrostatic form and thinking about how the frequency of that oscillation relates to the other fundamental constants in the universe like the speed of light and the planck constant, you might start to wonder, as I have, whether a wavefront at the speed of light would mass appear as a side effect because it was distorting space time so hard it was dragging it around?

Its a lot of fun to think about.

Re: What Is Space?

#46

Post by jacobolus »

tombh wrote: post #39
platz wrote: post #9

Earlier quoted context omitted.

there are no absolute reference frames. only relative ones! however, at least there is a fixed relationship between reference frames they all must obey with regards to the speed of light.

Just thinking out loud here. If the speed of light is absolute (it's not relative right? it doesn't change in any reference frame?), then could the speed of light be considered the base axis, or to continue the metaphor in the parent comment, that the speed of light is the 'outside the car'? Also, doesn't time 'stop' when you are at C, so that the whole idea of space (speed * time) sort of collapses?

You should spend some time doing calculations in the “hypercomplex plane”. That is, something like the complex plane, but where you’ve taken the real number line and added a a new value u such that u² = 1 instead of the value i such that i² = –1.

Try to work out what perpendicular numbers look like in this space, what “circles” look like (hint: like hyperbolae), what the tangents to those circles look like, what kind of metrical relationships arbitrary triangles or other shapes have, and so on.

If you play with this simple 2-dimensional number system for a while, you’ll come to understand the nature of special relativity much better.

* * *

The displacement between two points in spacetime can be either “spacelike” in which case there is some inertial reference frame in which the two points are simultaneous, or it can be “timelike” in which case there is some inertial reference frame where the two points are at separate times, unmoving in space, or the displacement vector can be “lightlike”, which is a boundary between the two – the two points are always in every inertial reference frame separated by some speed-of-light separation.

Re: What Is Space?

#47

Post by kobeya »

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

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.

Re: What Is Space?

#48

Post by kobeya »

ChuckMcM wrote: post #41
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?

> 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? It is a way (I'm not sure how to quantify it) to understand if someone can develop something that nobody has ever imagined before. My criteria for evaluating the response was whether or not the candidate could engage with the question. It is something that happened often in my experience…

> If someone was going to say "Well I don't know anything about that, ask someone else." Then the company knew they weren't going to be as successful as we would want them to be.

Except that is EXACTLY the correct response -- "I don't know, but I understand that physicists have a good idea of what space-time is, and I'll review the literature and see what the scientific consensus is and we can work from there."

The exact WRONG answer, in real life if not the interview, is "Hrm, I'm not sure but how about I make something up on the spot!"

Re: What Is Space?

#49

Post by ChuckMcM »

kobeya wrote: post #48
ChuckMcM wrote: post #41

Earlier quoted context omitted.

> 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? It is a way (I'm not sure how to quantify it) to understand if someone can develop something that nobody has ever imagined before. My criteria for evaluating the response was whether or not the candidate could engage with the question. It is something that happened often in my experience…

> If someone was going to say "Well I don't know anything about that, ask someone else." Then the company knew they weren't going to be as successful as we would want them to be. Except that is EXACTLY the correct response -- "I don't know, but I understand that physicists have a good idea of what space-time is, and I'll review the literature and see what the scientific consensus is and we can work from there." The e…

I completely agree with you.

When I said (paraphrased) "I don't know, ask someone else" I meant literally that. People who are asked a question about something they don't know anything about can either, do as you suggest propose a way to research the question (win), or do as I've observed refuse to go any further (lose). People who make things up on the spot generally are weeded out before we got to that point.

Re: What Is Space?

#50

Post by ryukafalz »

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”…

>Where/how is location stored?

Is this even a meaningful question? My understanding of "where" is that it's referring to a location within space.

Post reply on HN