Previous in Forum: Close-up Falcon 9 Launch   Next in Forum: Something to Make You Smile
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
Page 2 of 2: « First < Prev 1 2 Last »
Rate Comments: Nested
James Stewart
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162

The Land of No Shadows

09/11/2017 3:58 PM

OK, thought experiment:

(1) Mr. Flat resides in Twod world, where there are only 2 dimensions. Apparently, as far as he can tell there are no shadows in his world (hence the title of my question). The light source in his world is a very strange 2D star at the center of his star system. His house is really just a diagram, so light comes in through breaks in the line diagram, and the entrance.

(2) Suppose now that Mr. Solid Guy from ThreeD world (Earth) suddenly appears. He casts a shadow upon Twod world from his third dimension (height). Previously, Twod world had never, ever known anything about the sun, because there was no way to distinguish its light source.

Here is the question: IF we were to extend this rather distorted line of reasoning to ourselves in ThreeD world, and suddenly noticed a previously unknown kind of shadow (probably of unknown origin), would we declare the existence of the 4th dimension? Would it help to explain dark energy? Dark matter??? Am I barking mad up the wrong tree?

__________________
 If it ain't broke, don't fix it. Just build a better one.
Reply
Pathfinder Tags: dimensional shadows thought experiment
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Lehman57
Guru
Engineering Fields - Nuclear Engineering - New Member

Join Date: Sep 2009
Location: Louisville, OH
Posts: 1930
Good Answers: 36
#93
In reply to #92
 Find in discussion

Re: The Land of No Shadows

09/17/2017 5:41 PM

Now that my memory cells have been working a while, it's pretty slow, I think Flatland was also in the 4 volume set "World of Mathematics" which I think I received for Christmas in 1956. I'll have to dredge the bookcase to find it!

__________________
 Lehman57
Reply
Lehman57
Guru
Engineering Fields - Nuclear Engineering - New Member

Join Date: Sep 2009
Location: Louisville, OH
Posts: 1930
Good Answers: 36
#103
In reply to #93

Re: The Land of No Shadows

09/18/2017 3:16 PM

Found it! Volume 4 page 2385 in case anyone is looking.

__________________
 Lehman57
Reply
GM1964
Guru

Join Date: Jan 2007
Location: Edinburgh, Bonnie Scotland
Posts: 1336
Good Answers: 23
#95

Re: The Land of No Shadows

09/18/2017 6:41 AM

To exist and move, energy is required. Mass is required as a container for that energy. Mass requires a volume, so Twod land cannot exist.

__________________
 Madness is all in the mind
Reply
James Stewart
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162
#96
In reply to #95

Re: The Land of No Shadows

09/18/2017 9:49 AM

I can easily accept that rationale.

No one named dZ in Twod land. Even dZ would have to be named "Too tall", and would be the heaviest individual there.

What about ThreeD world not realizing we are really part of FourD world?

__________________
 If it ain't broke, don't fix it. Just build a better one.
Reply
Lehman57
Guru
Engineering Fields - Nuclear Engineering - New Member

Join Date: Sep 2009
Location: Louisville, OH
Posts: 1930
Good Answers: 36
#104
In reply to #95

Re: The Land of No Shadows

09/18/2017 3:20 PM

Why not? As a mathematical exercise it is useful to show extrapolation to the 3D and 4D spaces. This is 4 spacial dimensions, not space-time.

__________________
 Lehman57
Reply
tonyhemet
Guru

Join Date: Oct 2014
Location: Hemet, Land of milk and honey.
Posts: 2365
Good Answers: 36
#97

Re: The Land of No Shadows

09/18/2017 11:20 AM

Is this a homework question ?
Reply
James Stewart
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162
#98
In reply to #97

Re: The Land of No Shadows

09/18/2017 11:27 AM

Yes. and the other part of the answer is 42.

__________________
 If it ain't broke, don't fix it. Just build a better one.
Reply
StandardsGuy
Guru
Popular Science - Cosmology - Let's keep knowledge expanding Engineering Fields - Retired Engineers / Mentors - Hobbies - HAM Radio - New Member

Join Date: Dec 2006
Location: North America, Earth
Posts: 4528
Good Answers: 106
#105

Re: The Land of No Shadows

09/19/2017 12:04 PM

In the "spirit" of this thread, let's drop the impossible 2-dimensional word and just use our 3D world with it's impossible point particles.

__________________
 “I would rather have questions that can't be answered than answers that can't be questioned.” - Richard Feynman
Reply
James Stewart
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162
#106
In reply to #105

Re: The Land of No Shadows

09/19/2017 12:14 PM

What point particles? I thought all particles have some volume (along with whatever mass they carry), however tiny that might be.

Does it explain sandy grit in the Chik-Fil-A salad my wife had last night? Or is someone in the kitchen sending us a "go-away" message?

__________________
 If it ain't broke, don't fix it. Just build a better one.
Reply
Reply to Forum Thread
Have a Different Question?
Page 2 of 2: « First < Prev 1 2 Last »

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Alex. Roman (1); Calnet42 (1); Conman (1); Deefburger (1); dkwarner (1); Doorman (3); Fredski (1); Gavilan (3); GM1964 (1); Hannes (1); horace40 (1); James Stewart (44); JBTardis (1); JE in Chicago (2); Jpfalt (3); JPool (3); Lehman57 (5); lyn (1); mikenelson6 (2); MR. Guest (1); ndt-tom (5); phoenix911 (5); PWSlack (1); Rixter (1); ronc (2); SolarEagle (10); StandardsGuy (1); tcmtech (2); tonyhemet (1); Usbport (1); user-deleted-1105 (1); yamdankee (2)

Previous in Forum: Close-up Falcon 9 Launch   Next in Forum: Something to Make You Smile

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Aerospace:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (34 right now)
Show Members
Advertisement