What Does Dark Energy Really Do?

Dark energy, what exactly does it do? Find out in this episode of Space Time! Part 3 in our Dark Energy series.
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How does dark energy affect the universe's expansion? Measuring past expansion history should tell us the future expansion without ever having to count any galaxies. To measure this we need to measure the redshift-distance relationship, which we will talk about in detail in this episode.

Written and hosted by Matt O’Dowd

Comments
Pravar Parekh

Yeshwanth Vejendla

Thomas Waclav (Ceasar)

Austin Pinheiro
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[Asimovum]

This guy could convince me that i'm actually a carrot

[pgoconn]

"Thanks to you for being honest about the strength of the evidence behind your belief structure." Beautiful.

[DefinedEdits]

When playstation exists but I spend my free time watching videos on theoretical physics.

[izvarzone]

In old times it was called Universe Expansion

Now its called Universe DLC

[symbioticcoherence]

If there is a company called Apple, there can be a company called Peanut Butter Sandwich Digital Studios.

[CautiousMeat]

This is the greatest science show ever. Everything on here goes way over my head, but that's why I like it. I have to re-watch these videos to understand them. Thank you for not simplifying everything just to cater to the average person.

[coquio]

Is it me, or are Mathew's shirts getting tighter with every episode?

[SonicRooncoPrime]

Another excellent video from Peanut Butter Sandwich Digital Studios.

[AndrewK]

I don't understand any of this, and yet, I still watch.

[youduntknowmyname]

If I ever do an astrophysics course I know where to get my summaries.

[EugeneKhutoryansky]

My view is that "dark energy" in General Relativity will turn out to be analogous to the precession of the planet Mercury in Newtonian physics. That is, it is an indication that our present model for the fundamental laws of physics is incomplete, and that the true nature of the Universe is far more mysterious and remarkable than we had ever previously imagined.

[EdouardOlszewski]

Is the "Vacuum energy" you mentioned around 7:40 anyhow related to the Casimir effect? It seems to talk about something somehow similar...

[CarBENbased]

"Thanks to you for being honest about the strength of the evidence behind your belief structure" Oh snap, shots fired! lol

[GreyFang]

mmm...I'm going with *P* izza *B* ased *S* cience. All knowledge can be teased out over a hot slice!

[avi_mukesh]

One day... One day I'll be able to understand everything on this channel (I hope :/)...

[Algebrodadio]

Thank you +PBS Space Time for making GR accessible to a general audience.

[ewanhassall]

Can't decide whether that was a dis on religion. 12:23

[StephenGillie]

Redshifting is a loss of energy of a photon. As the photon moves through space, it slowly loses energy to the expansion of the universe over time. Which is odd, because photons don't experience time, since they move at light speed. This coupled with the concept that the universe is just World Lines in 4D Spacetime, and time is an illusion begs the question of how the universe is expanding over time, if time is just an illusion. Is the 4D Spacetime larger at one end than the other? Or is this just a conceptual illusion like the Observable Universe?

[adamtaylor]

Your hair is like a luscious lions mane

[jarodtall]

He just roasted religion with his final comment. Classic stuff.