Einstein's fairy tales about photons are even more fabulous than his theory of relativity. A particle without mass is very cool! )))
Antigonish poem by Hughes Mearns --
Yesterday upon the stair,
I met a man who wasn't there
He wasn't there again today
I wish, I wish he'd go away...
When I came home last night at three
The man was waiting there for me
But when I looked around the hall
I couldn't see him there at all!
Go away, go away, don't you come back anymore!
Go away, go away, and please don't slam the door ... (slam!)
Last night I saw upon the stair
A little man who wasn't there
He wasn't there again today
Oh, how I wish he'd go away...
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"A particle without mass is very cool!"
So is an observable universe without mass!
(The map is not the territory.)