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I want to know some accurate informations regarding the time-energy uncertainty principle.

From several websites i got that [tex]\Delta[/tex]E[tex]\Delta[/tex]t[tex]\geq[/tex][tex]\hbar[/tex]/2 (for e.g., hyperphysics, wiki, etc.).

But in some books they use [tex]\Delta[/tex]E[tex]\Delta[/tex]t[tex]\geq[/tex][tex]\hbar[/tex].

Can anyone clear this why it is like that...Also is there any small derivation for that?

Thanks.

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# Uncertainty rule

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