What is the Hubble Constant? Daniel Holz measures the universe's expansion using gravitational waves

Ripples in the fabric of spacetime, called gravitational waves, tripped alarms at two ultra-sensitive detectors. This event provided professor Daniel Holz the information he needed to make a groundbreaking new measurement of one of the most important numbers in astrophysics – the Hubble constant, which is the rate at which the universe is expanding.

The Hubble constant holds the answers to big questions about the universe, like its size, age, and history, but the two main ways to determine its value have produced significantly different results.

Now there was a third way, which could resolve one of the most pressing questions in astronomy—or it could solidify the creeping suspicion, held by many in the field, that there is something substantial missing from our model of the universe.

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(Subject Tags: A new way to measure the hubble constant. Using gravitational waves to determine what the hubble constant is. Measurement of the age of the universe debate has a new solution.)

[Tanengtiong]

The theory that the universe is accelerating already won't Nobel prize

[ThestDukeDroklar]

How do we know the redshift measurement is accurate?
1- We have strong evidence that quantum foam exists. We don't know if the quantum foam is more energetic in intergalactic space outside of gravity wells. We also don't know how light passing through quantum foam is affected.

2- How do we know that the wavelength of light is not naturally redshifted due to the immense distances covered?

[puffy]

I think it’s very important for the new coming generations to take more interest in broadening their understanding of even just space around them. We take for granted the beauty and complexity of our universe. I’m currently 15 but I hope to be able to continue my study’s into the way space as we know it truly works but I’m ever so discouraged due to the fact of how undeveloped our brains and our understanding is. When people say we are merely a speck even to our galaxy, it shows tremendously in the evolution to the capacity of our comprehension involving matters outside of our day to day lives. If we have yet to go extinct on account of the utter negligence we have as a society for the mental and physical health of earths contemporary and posterior hosts, Hopefully future human minds have greatly advanced and allow for man kind to inhibit a more accurate perception of the universe and everything it bears for the future civilization to unravel.

[geworthomd]

This was nice. I still don't believe we have a good explanation for why the visible universe is flat or flat with a convex or concave bend. I think you could be the person to discover what keeps the Milky Way flat. It cannot be expansion based in the theory. It cannot be macroscopic vs microscopic point reference based in theory. It has to be an asymmetrical force that works on the Z axis to keep the universe flat (X, Y based). What if the Inflatron lost energy, more at it's center than it's periphery. Matter formed at the center, cooler area. The energy to expand was asymmetrical to begin with from the very start. The inertia has just kept the template (flat). Why and what energy allowed the expansion to be asymmetrical? I cannot get my head around it just being a frame of reference, a dot of a hugely expanding universe (visible universe and beyond). The only way a flat sheet of universe (ah, with convex and concave bends to the sheet) is possible is for a yet unidentified force working in the Z plane or something the resisted the early expansion in the Z plane. Go for it, find it, discover and let all of us pions learn from what you have found. I like that you didn't just repeat the other author's explanation for the flat universe (and flat galaxies) based upon macro /micro perspectives of the geometry of the universe. Yes, everyone can say the same things at the meetings but to be honest, it doesn't make sense. CMB is diffuse in 3 dimensions. Matter has a tendency to be X, Y planar in the known universe. Some day...

[fornax]

Grate video and exactly the info on Ho I was looking for.

[davidanderson]

Here is a question. There are zero asumptions in my question. (It may be a good question, it may be a logical question, but simplistic, with known answers, and I am simply not educated in the field.)
Say we observe light from a galaxy 10 Billion light years away.
Are there not NUMEROUS disparate past factors, no longer active NOW, over the 10 billion light years of travel to us, that could have affected the light spectrem we prerceive now?

If, say 9 billion years ago, something (anything, the expansion rate of space, the various gases of another galaxy that is no longer there, etc) was cause to a shift in the spectrum of light from said galaxy, and that causative factor was no longer active, would the light we perceive now not still carry that PAST spectrum shift message, despite the fact that the cause of said shift is no longer affecting the light?

(Say in the first billion years of said light leaving that galaxy space WAS expanding very fast, and that billion years of red shifted light is only reaching us now, would the light still record that past expansion for the next billion years or so of our experience of it?) Is it possible that we are measuring how fast space was expanding over time?

And, if the expansion of space has steadily slowed over our 13.6 biillion years, would not our observational time lapse observation of said red shift, give the perspective of ever increasing expansion as we look ever deeper into the past?

In other words the steady decay of expansion rate over time, would produce the illusion of ever more rapid expansion, the further distance into the past one observed?

It does not appear that the disparate "ladder" measurements of star and galaxy distance overlap, or confirm distance AND recessional velocity. Telling the standard candle brightness does not give red shift, and red shift can only give expansion rate of said light, over the TIME of its journey. Therefore it appears that a steady drop in expansion rate over TIME, would produce the hubble constant, and mimic an ever increasing expansion over distance.

[ND-dgxo]

Are we sure the universe is expanding uniformly? That sounds like a big assumption made from our limited vantage point.

[justindougherty]

Question. How will Andromeda collide with our galaxy if everything is supposed to be moving away. Last i checked explosions throw things out and away so how did the big bang happen yet Andromeda is moving towards us through space Thats expanding how fast between us....