Talk:Tipler cylinder

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Removed weird claim

Note that such spacecrafts would (ideally) be of a 'flying saucer' shape, i.e. flat, disc like objects.

Whoever wrote that, you're gonna have to explain this one (in the article) if you want to put the claim back in.---CH (talk) 09:30, 2 September 2005 (UTC)[reply]

Note: Michio Kaku's 'Parallel Worlds' mentions this idea in chapter 5 and attributes the idea to W.J.Van Stockum, in the section titled "Van Stockum's Time Machine"

Here's what the previous comment is about: http://www.wired.com/wired/archive/11.08/pwr_timetravel.html?pg=2&topic=&topic_set= "Although Van Stockum himself didn't recognize it, anyone orbiting such a cylinder in the direction of the spin will be caught in the current and, from the perspective of a distant observer, exceed the speed of light." —Preceding unsigned comment added by 91.109.206.100 (talk) 21:15, 14 December 2008 (UTC)[reply]

Weak arguments

Currently the article has this quote from Hawking "it can't be done with positive energy density everywhere! I can prove that to build a finite time machine, you need negative energy." What is "I can prove" supposed to mean? Either he has proved it and then we need a reference to the proof or he hasn't in which case his comment is worthless and should be removed.Enemyunknown (talk) 18:53, 24 December 2008 (UTC)[reply]

It doesn't really matter, under the wiki policies his comments are inherently notable in this context. To override this you would need to find someone notable who disagrees.- (User) Wolfkeeper (Talk) 19:12, 24 December 2008 (UTC)[reply]

As far as need for an expert, Dr. Tipler is a professor at Tulane University. I am taking a physics class from him now. I'll ask him to have a look at the page. —Preceding unsigned comment added by 129.81.74.154 (talk) 04:45, 10 March 2010 (UTC)[reply]

Possible plagiarism

I notice the following page includes a large section of identical text: http://www.andersoninstitute.com/tipler-cylinder.html At the bottom it states "Copyright © 1990-2012, The Anderson Institute. All rights reserved." There doesn't appear to be any acknowledgement of the source but I'm not sufficiently familiar with Wiki to say if that's a problem. George Dishman (talk) 10:05, 19 June 2011 (UTC)[reply]

See here for dealing with copyright violations [1]. IRWolfie- (talk) 13:29, 19 June 2011 (UTC)[reply]

The Anderson Institute copied the text from wikipedia, not vice versa. The earliest archived version of their Tipler Cylinder page is from Nov. 1 2009, but you can see from the wiki page's revision history that as of October 2009 most of that text was already in the wiki article. Also, you can see from this March 2007 revision that I myself added the material on Hawking's proof that finite-length cylinder wouldn't work, I can vouch for the fact that I never heard of the "Anderson Institute" until checking back on the Tipler Cylinder wiki page today (also note that at the bottom of the archived Anderson page on Tipler cylinders it says "Copyright © 2008, The Anderson Institute", so even their own original copyright notice is later than my edit about Hawking...only later did they change the copyright at the bottom of the page to "1990-2012"). Hypnosifl (talk) 01:08, 10 January 2014 (UTC)[reply]

Infinite Cylinder ?

The article says, "An objection to the practicality of building a Tipler cylinder was discovered by Stephen Hawking".

Would someone knowledgeable in the subject please explain the totally obvious practical objection that a cylinder of infinite length would require an infinite amount of matter to build, would take an infinite amount of time to build, and need an infinite amount of energy to even start it rotating, and there just isn't that much matter and energy in the universe ? (And probably not enough time !-)

It doesn't really need Stephen Hawking to figure that out. It's not even rocket science ! Darkman101 (talk) 21:57, 16 September 2011 (UTC)[reply]

Hawking's discovery wasn't that building an infinite cylinder would be impractical, rather his discovery was that only an infinite cylinder would work for time travel, contradicting Tipler's earlier speculation that a finite-length cylinder might do the job. Hypnosifl (talk) 06:05, 10 January 2014 (UTC)[reply]

Possible time travel?

How? Wouldn't anything be crushed by an immense amount of g-force? Or wouldn't it be crushed by the gravity? Is this orbiting spaceship or flying saucer or whatever going faster than the speed of light? Wouldn't this raise all the same issues as using a black hole to travel in time? This article is extremely lacking in detail! — Preceding unsigned comment added by 109.153.170.218 (talk) 20:31, 6 November 2012 (UTC)[reply]