# Color Holograms

#### Wendy

Joined Mar 24, 2008
23,317

#### magnet18

Joined Dec 22, 2010
1,227
Awesomesauce

I hope this actually gets applied to things, instead of falling into obscurity like most cool tech.

#### jpanhalt

Joined Jan 18, 2008
11,087
Awesomesauce

I hope this actually gets applied to things, instead of falling into obscurity like most cool tech.
Yea, I know what you mean. Just look what happened to the slide rule, Teflon, lasers, PET scans, and so forth.

John

#### magnet18

Joined Dec 22, 2010
1,227
Yea, I know what you mean. Just look what happened to the slide rule, Teflon, lasers, PET scans, and so forth.

John
That't the cool tech that does get applied, theres plenty of cool stuff that has yet to be applied wide scale.
Surface interface computers
hovercrafts
3D projection holograms
ect.
Granted, most of it isn't practical, but still...

#### jpanhalt

Joined Jan 18, 2008
11,087
Hovercrafts? Come on. They're a gadget at best. Et cetera? Well, when someone gives me an et cetera I can use, I might agree.

John

#### magnet18

Joined Dec 22, 2010
1,227
Better than slide rules, c'mon, MECHANICAL MATH??
pshh
(I kid )
I actually intend to get a slide rule sometime soon... Purdue doesn't allow Calculus 1 students to use calculators...

#### jpanhalt

Joined Jan 18, 2008
11,087
Purdue doesn't allow Calculus 1 students to use calculators...
That is a great idea. Students need to "see" the problem, not simply solve it by brute force. Take the thought experiment of a rope that is tightly strung around the equator. Now, someone adds just 6 feet to it. How far will the rope be raised uniformly around the earth? Any idiot can solve that with a calculator, but to solve it with a slide rule (or in your head) requires understanding the problem.

I think you will really enjoy Purdue.

John

#### magnet18

Joined Dec 22, 2010
1,227
answer, such a small amount that the rope could still be considered tight... or less than I'm willing to calculate through long division.
Lets hope I get accepted.

#### jpanhalt

Joined Jan 18, 2008
11,087
Show your work. (I think if you write the equations, you will see your error.)

John

#### magnet18

Joined Dec 22, 2010
1,227
How tight is this rope?
Because most rope has a significant amount of elasticity, especially considering that it's stretched over 25000 miles...
(doing the math again, back in a minuet... I guess I can consider this studying for my precalc test )

#### magnet18

Joined Dec 22, 2010
1,227
Alright, I got about 3 digits through long dividing before I realized that I only needed to look at the last digit, and it would rise about a foot... As I was typing this I was thinking about why that would be since it didn't make sense and realized theres a ratio irrespective of size and that adding just 6.28 feet would rise it exactly 1 foot, which was fun, and I still think the point was moot since it would still be absorbed by the rope as slack, but you've made your point
(last time I worked in miles... *facepalm*)

#### jpanhalt

Joined Jan 18, 2008
11,087
It was a though experiment, which means don't worry about the rope stretching. Setting up problems correctly can save an enormous amount of calculating and reduce errors. It also helps one to develop analytical skills. Over reliance on that little handheld calculator can become disabling.

Sorry to get so OT. My initial comment was really meant as a quip to disagree with your assertion that most "cool tech" falls into obscurity.

John

#### magnet18

Joined Dec 22, 2010
1,227
OT?
Old Teacher?

I know it was a thought experiment, which is why I did it, I just brought up the rope streching because I like presenting alternate solutions whenever possible, and I've gotten used to solving odd problems in unusual ways.
Like making 2 vheicles work together to tie a knot in a piece of rope, or making a 3"tall 12"long remote controlled vehicle climb vertically 3 feet up a wall.
Those were the fun days...