Penrose diagram of an infinite Minkowski universe.
<a href="https://en.wikipedia.org/wiki/User:Cronholm144" class="extiw" title="wikipedia:User:Cronholm144">Cronholm144</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>
19 July 2007 (original upload date)
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