Skepchick Presents: A Conversation with Dr. Neil deGrasse Tyson (Part 2)

[lazyperfectionist1]

Wait. I thought dark energy didn't actually exist. I thought Einstein posited it to explain the lack of collision between stellar bodies before such was explained by the continuous expansion of the Universe.

[Al3xX420]

"Our common sense is derived from life as human, not life as an electron."

[equallyeasilyfuqyou]

so cool, haven't seen this interview of NTD, he rules.

[Katalyzt]

★★★★★

[leporidus]

Why again can't dark matter be virtual particle/antiparticle pairs? Gotta look that up

[MichaelKingsfordGray]

Because virtual particles have zero total energy, by definition.

[leporidus]

I agree. If space-time is flat, the whole universe has total zero energy (yeah, I just watched Lawrence Krauss' AAI 2009 talk).

Nevertheless, even virtual particles should have mass for the few femtoseconds they exist. I'm struggling; I just suspect they couldn't easily be counted as dark matter, because they wouldn't be weakly interacting, unlike WIMPs and axions.

[MichaelKingsfordGray]

See wikipedia for a brief explanation:

"...A virtual particle is one that does not precisely obey the m2c4 = E2 − p2c2 relationship for a short time. In other words, their kinetic energy may not have the usual relationship to velocity — indeed, it can be negative."

[leporidus]

O-oh, that's a whole can of worms I have to dig my teeth in (sorry for the unappetizingly mixed metaphors).

Thanks for the pointer, Michael! You live and learn

[lehman]

third