What Is Dark Energy?

Galaxies have been flying apart faster and faster since the early universe. Astronomers say the culprit is dark energy. But what is dark energy?

Host, Producer: Greg Kestin
Research, Writing: Samia Bouzid, Greg Kestin
Editorial Input from: Julia Cort, Ari Daniel
Filming, Editing, and Animation: Greg Kestin
Science consultant: Steven A. Rodney, Mark Trodden
Media courtesy of ESO, NASA
Special thanks: Entire NOVA team
From the producers of PBS NOVA © WGBH Educational Foundation
Funding provided by FQXi
Music provided by APM

[sherkerabesson]

Mind blowing! I hope I can live long enough to see some of the amazing discoveries

[stz]

Really blew my mind apart, the idea that new repulsive bubbles could just keep on popping into existence! Thank you for shedding some new light into this seemingly dark concept!

[WhatThePhysics]

Hey Hey! Next video coming is, "What does an atom actually look like?"

Also, if there's something you want to see a video about, let me know!!

[Tom-lrwc]

*It seems like common sense to me: Newton's 2nd Law: 'For every action, there is an equal and opposite reaction.'
If 'gravity' pulls objects together, than 'dark energy' pushes objects apart.
With 'gravity', objects closer to source move faster, exponentially.
But with 'dark energy', objects further to source move faster, exponentially.
As we move further from source 'big bang', 'dark energy' strength > 'gravity' strength.
Universe never has 0 energy at any region of space.
Universe is a physical field with certain amount of energy (quantum fluctuations) in each tiny region.
All actions are 3D in nature, and spherical.
Matter(object) are just points on a physical spherical wave of energy, that possible originated from a 'big bang'. Although a creation theory, created just to please religions and avoid conflict, seems more likely.
Universe is far larger than any observations can indicate.
Does an aether in some form exist? Seems likely.
Time is not real, as from light's perspective, light does not experience time.
Why does light seem to spread out its energy, and gravity seem to attract?
Why do all sources of light, always have to come from matter? eg Sun's light, comes from electron displacement in atoms.
We just don't have the capability to understand Natural Phenomena yet.... for now.
We really need to open up our mind's to new and better views of reality.*

[novapbs]

Geez, Greg—way to call us out on our inaccurate animations! We're doing the best we can. It's ok, though. We still love you!

[flewjewcoop]

I sure am glad my refrigerator has a dark energy strip to keep it closed.

[llmarianaospina]

Makes me kinda sad honestly. If humanity lives long enough we might not be able to see as many stars as before

[DrakeLarson-jspx]

This is an excellent video.
Reasonable conjectures for dark energy are gravity ‘inversion’ concepts. These concepts can be thought as extensions of what Einstein demonstrated in 1905-1912. This sort of gravitational inversion can explain curiosities like the redshift and dark energy by using geophysics data gather by Fowler, Anderson and Dziewonski. Their remarkable data can be interpreted as a dark energy example in a rather straightforward manner via tensor analysis.

[thorodinson]

Lol...when u said ...“if u throw a baseball and it never stopped..! And video starts buffering😂

[hbkjnhbjk]

I saw a video of yours earlier and I dondont understand how can you change the past by traveling faster than the speed of light? Woudnt it change present?

[AmyDaryleKonczal]

Imagine a campfire from a distance with infrared vision. You would see a near perfect sphere of heat not emanating soley from heat energy pushing outward but also balanced by colds repellent effect balanced by each other. See cold seeks to destroy heat. So therefore cold and heat are balanced in an infinite cosmic struggle for supremacy. Just like the heat of galaxies and stars are pushing outward and being balanced by the empty voids full of colds repellent effect.

[chekovjojo]

I like it but how you get this videos images

[prathamsabharwal]

The expand of space can be due to the gravitational pull by the heavenly bodies in space . This is like they are flattening the space and not expanding it just like pulling a rubber band, it gets stretched.

[icri]

uh....i really want to know that we just see the stars and stuff drifting apart at it may not necessarily be expansion nut rather contraction?

[anjaneyjain]

Sir,
I have a query to ask, it is believed that energy cannot be created or destroyed. So, therefore energy should be a constant value. It is also true that the universe is expanding and accelerating its expantion, which needs force. A constant force or energy can only accelerate an object to a specific velocity. But here the universe seems to accelerate to an infinite velocity. The query is that, from where does this energy coming which causes this acceleration, if energy is constant. It seems as if energy is being created in this process. Dark energy should also be a constant force. Also, if the things discovered till now are true, than the acceleration of the universe should stop at some time.
Kindly revert to my query.
Thank you

[onderozenc]

Virtual particles are the Quantum fields in other words the displacement currents but how to explain the repulsion among them ?....Maybe multiple isospin interactions....

[francescofavro]

staying in the bubbles analogy, you said that when these bubbles pop into existance they "create" space for themselves. but when they disappear, as virtual particles do, shouldn't the space fold back into itself?
it's probably just a limitation of the analogy.

[ektordarzentas]

What if c wasn't constant in void and the universe expansion wasn't accelerating

[personanongrata]

I can't begin to understand the math involved, but If the universe is expanding faster than we expect, based on how we observe red shift, could it just be our local time dialation? Time passes slower within the proximity to mass. Could it just be we are moving slower through time than the interstellar medium? Likewise the Mass we are observing moving slower than the space in between? Like a time-dependant paralax error? Theres a glaring hole in my theroy, I'm just too dumb to see it. Someone please help me here.

[Jibbie]

Looking up information about the host, I found : Greg Kestin holds a faculty position at Harvard University, where he conducts theoretical physics research, teaches, and produces educational online content. He earned his physics Ph.D. from Harvard, as a member of The Center for the Fundamental Laws of Nature, focusing on theoretical particle physics and quantum field theory. Over his career, he has also conducted research in nuclear physics, fusion energy, and gravitational wave physics.