Smeggy's Forums

Forums where you CAN vent!

Skip to content

Physicists testing to see if universe is a computer simulati

Into science? Chat about its amazing wonders here. E really does equal MC^2 -> Einstein would be proud!

Top Forum Index Page New Posts

Posted on

      

Channel Hopper wrote:
ghostgirl wrote: Is there such a thing as constant motion? Or does absolutely everything progress in discrete intervals?


If it were the case, interlacing might explain how other world inhabitants are able to move around this planet unnoticed.


You mean in the gaps? Huh, interesting possibility, Isupposeit'sabitlike'words'beingcompleteandutternonsensewithoutthespacesinbetween :D

Image
"TONGUE-tied and twisted, just an earthbound misfit, I"

User avatar
Haunting Beauty
Posts: 4600
Joined: Fri Feb 20, 2009 4:20 pm
Location: Scotland
Current Mood: Spine chillingly spooky

Top Forum Index Page New Posts

Posted on

      

smeggypants wrote:I'm not sure. I do remember hearing about some theory that the Universe could be granular. How you would test it while being stuck within the quantisation itself I Dunno :)


That would be Quantum Mechanics, although it doesn't actually hold that spacetime is discrete, just that there's a smallest useful division of spacetime. It's agnostic on whether spacetime is fundamentally granular.

However, the current theory that has spacetime as inherently discrete is M-Theory, and this feature is one of the things that makes some physicists think that it might be the answer to marrying Quantum Mechanics and General Relativity. GR requires that spacetime be smooth and flat, while QM tells us that, on the smallest of scales, spacetime is anything but smooth and flat, and is actually roiling and coarse. M-Theory provides a get-out clause, because it tells us that there is a limit beyond which spacetime cannot get any smaller, because it's constituted of discrete entities (strings) whose smallest scale is the Planck length.



User avatar
On a roll!
Posts: 109
Joined: Sat Jan 19, 2013 1:01 am
How Hot Are You?: A Nice English Summer's Day
Current Mood: unknown

Top Forum Index Page New Posts

Posted on

      

hackenslash wrote:
smeggypants wrote:I'm not sure. I do remember hearing about some theory that the Universe could be granular. How you would test it while being stuck within the quantisation itself I Dunno :)


That would be Quantum Mechanics, although it doesn't actually hold that spacetime is discrete, just that there's a smallest useful division of spacetime. It's agnostic on whether spacetime is fundamentally granular.

However, the current theory that has spacetime as inherently discrete is M-Theory, and this feature is one of the things that makes some physicists think that it might be the answer to marrying Quantum Mechanics and General Relativity. GR requires that spacetime be smooth and flat, while QM tells us that, on the smallest of scales, spacetime is anything but smooth and flat, and is actually roiling and coarse. M-Theory provides a get-out clause, because it tells us that there is a limit beyond which spacetime cannot get any smaller, because it's constituted of discrete entities (strings) whose smallest scale is the Planck length.


I'm not sure if M-Theory has really been formally defined yet, except to say that it requires something like another 11 dimensions if I recall correctly. Not that you could ever experience them, they are very very tiny. Isn't the problem with String Theory to do with the fact tthat many calculations end up with unacceptable infinite numbers?

Image
"TONGUE-tied and twisted, just an earthbound misfit, I"

User avatar
Haunting Beauty
Posts: 4600
Joined: Fri Feb 20, 2009 4:20 pm
Location: Scotland
Current Mood: Spine chillingly spooky

Top Forum Index Page New Posts

Posted on

      

But doesn't infinity ( other than in maths ) have to exist by default?

-----|0| None are more hopelessly enslaved than those who falsely believe they are free. |0|-----

"Capitalism profits from War - Humanity profits from Peace."

User avatar
Aliens Ate My Chicken!
Posts: 118322
Joined: Sat Dec 15, 2007 8:32 am
Location: Smegland
How Hot Are You?: The Big Bang!!
Current Mood: Won Tons Mons

Top Forum Index Page New Posts

Posted on

      

The only other alternative is 'something out of nothing' OR 'nothing out of something'

-----|0| None are more hopelessly enslaved than those who falsely believe they are free. |0|-----

"Capitalism profits from War - Humanity profits from Peace."

User avatar
Aliens Ate My Chicken!
Posts: 118322
Joined: Sat Dec 15, 2007 8:32 am
Location: Smegland
How Hot Are You?: The Big Bang!!
Current Mood: Won Tons Mons

Top Forum Index Page New Posts

Posted on

      

ghostgirl wrote:I'm not sure if M-Theory has really been formally defined yet, except to say that it requires something like another 11 dimensions if I recall correctly.


Well, it's been formally defined, but the problem is that it isn't really very well understood, not least because the mathematics is horrendously complicated.

Not that you could ever experience them, they are very very tiny.


Depends what you mean by 'experience'. Here's a post I wrote for another forum dealing with how we might be able to observe tiny dimensions:

hackenslash wrote:It's worse than that. There is categorical evidence that there can never be any such thing, and without even appealing to such esoterica as the uncertainty principle. Everything, and I do mean everything, is transparent to gravity, so it is never absent. Indeed, and once again appealing to esoterica, it is postulated that the reason that gravity is comparatively weak is that even hidden dimensions are transparent to gravity, and that its weakness is due to it 'leaking' into other dimensions. There are, in principle, tests that can be carried out to confirm this. They get a little technical, but they are to do with the implications for more dimensions on the inverse-square law. In a nutshell, the inverse-square law is a consequence of our inhabiting a three-dimensional cosmos. I'll try to explain:

If you take photons as an analogy (they also obey an inverse-square law, as any photographer will tell you), you can see how this works. Photons travel in straight lines, and radiate out from a centre. In a one-dimensional universe, you would receive the same number of photons from a source, regardless of how much you were separated from that source, because there is only line they can travel. In a two-dimensional universe, the light falls off in direct proportion to separation, because the lines they travel are uniformly spread on a circle, and the circumference of the circle is proportional to its radius. In a three-dimensional universe, the fall-off follows an inverse-square law because again, the lines travelled are uniformly spread over the surface of a sphere whose area is proportional to the radius. In a universe with four spatial dimensions, the fall-off would be inversely proportional to the cube of the distance, for exactly the same reasons.

So, now we know why gravitational attraction is inversely proportional to the square of the distance in three dimensions, and surely we can't live in a universe with more than three dimensions, because we'd measure a different law for the fall-off of gravity (and photons), but we don't! However, this conclusion would be a premature, because it only deals with the large scale of the cosmos we've been able to observe. If, for example, the extra dimension were curled up to around the Planck length, then the inverse-cube law would only hold to those distances, and from there we would experience an inverse-square law, as the propagation of gravity (and photons) would follow the three-dimensional principles.

At the smallest distances we've been able to probe, there has been no violation of the inverse-square law, but bear in mind that the smallest distances we've been able to probe for this is about a tenth of a millimetre, which is many orders of magnitude greater than the Planck length. If we ever find violations of the inverse-square law, it will provide extremely robust evidence for the existence of small dimensions.


Isn't the problem with String Theory to do with the fact tthat many calculations end up with unacceptable infinite numbers?


Some of that has actually been addressed, because it turns out that taking advantage of something called 'dualities' means that where a calculation under one iteration of string theory gives infinities, using another iteration with 'duality' renders the solutions tractable. It is this framework of dualities with which String Theory has been tamed, and this framework is what we call M-Theory.



User avatar
On a roll!
Posts: 109
Joined: Sat Jan 19, 2013 1:01 am
How Hot Are You?: A Nice English Summer's Day
Current Mood: unknown

Top Forum Index Page New Posts

Posted on

      

There's nothing inherently wrong with 'infinity' from a mathematics point of view. From the viewpoint of physics though? Infinity isn't the issue there either imo, more specifically the infinity, not of 'Space', but of 'Time', is the problem. Once 'Time' is brought into the equation we have the problem of beginnings and endings, - 'something from nothing', etc... We had a discussion a year or two ago relating to this, and I said then that I think 'time' is a fictitious dimension which nether language, not the human mind itself for that matter, can really overcome.

HOWEVER... ...I will try.

We speak of 3 dimensions + Time but often we interchange distance (i.e. Length) and Time, - if someone says to me, "How far is it from here to Manchester?", I might say 220 miles. On the other hand I might just answer, "Oh about 2 and a half hours...", thereby interchanging Distance and Time.

3 Dimensional Universe
1st dimension = Length (a line on a page), 2nd dimension = Breadth (a line expanded widthways to produce a flat surface), 3rd dimension = Height (a flat surface expanded 'up' or 'down' to produce a cube).

What if this is incorrect?

Try this:

1st dimension = just a set of 'empty' co-ordinates (i.e. a Placeholder in Space), 2nd dimension = a set of co-ordinates containing an Elementary Particle, which is probably billiard ball shaped and so is in itself 3 dimensional (indicating that the 2nd dimension is really already the 3rd, as we currently know it), 3rd dimension = many Elementary Particles adhered together, to produce, well, a bigger piece of Matter. OR, alternatively, it might be the same initial Elementary Particle existing in many other 'Now's' (i.e. existing merely at an adjacent set of co-ordinates). Which in effect makes Elementary Particles 3-dimensional, 'Space' something with infinite dimensions, and 'Time' ...non-existent. :D

Image
"TONGUE-tied and twisted, just an earthbound misfit, I"

User avatar
Haunting Beauty
Posts: 4600
Joined: Fri Feb 20, 2009 4:20 pm
Location: Scotland
Current Mood: Spine chillingly spooky

Previous

Share this Topic on Facebook:

Return to General Science

Similar topics

  • Topics
    Replies
    Views
    Last post
    Top of Page

Who is online

Users browsing this forum: No registered users and 3 guests