Antigravity does not exist?

dark en·er·gy
a theoretical repulsive force that counteracts gravity and causes the universe to expand at an accelerating rate.
"Einstein's theories allow for the possible existence of dark energy"
Update 2: But in the new study, Massimo Villata, an astrophysicist at the Observatory of Turin in Italy, suggests the effects attributed to dark energy are actually due to a kind of "antigravity" created when normal matter and antimatter repel one another
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