#hubble constant

[zespaceblog]

Refsdal and the Hubble Tension

In astronomy, a bit of luck can go a long way, and in 2014 Patrick Kelly still a graduate student was looking through Hubble images by eye, no different to many of you here looking through the images posted on this very blog, but Kelly spotted something interesting in the distant images of far flung galaxies taken by Hubble, a supernova gravitationally lensed.

The supernova was behind the galaxy, and lensed into 4 different locations, and yet, it appeared to be missing a 5th replicated image, which Kelly assumed had somehow been delayed in it's arrival.

Sure enough, many months after the supernova had vanished and almost a year later, the missing image of the supernova arrived.

It's hard to imaging how the same light, split across lensing can take an entire year's detour, but sure enough it did.

Kelly then joined forced with other astronomers to see if they could use the images to predict the Hubble constant, the rate of expansion of the universe.

The problem with the Hubble constant is, every time we measure it with a different method, we seem to get inconsistent responses, and this has led to the Hubble Tension.

Above are a list of different methodologies. The model used for the supernova isn't included in the above diagram, but it falls at 63.3 to 70.7 km/s/megaparsec, right alongside the Plank measurement as an early universe sample (Plank deriving it's measurement from the CMB from the big bang). While there is a huge amount of uncertainty in most of these models, it's difficult to be sure, but so far it does seem the earlier we look, the slower the Hubble constant is, making it not particularly constant at all.

[exhaled-spirals]

« The Hubble Constant can be defined simply as the rate at which the Universe is expanding, a measure of how quickly the space between galaxies is stretching apart. [...] Extrapolating the expansion process forward presents two starkly opposed futures, either an endless era of expansion and dissipation, or an eventual turnabout that will wipe out the current order and begin the process anew.

In scientific parlance, the Hubble Constant is expressed in units of kilometres per second per megaparsec, but cosmologists rarely speak of it in that abstruse way. They typically discuss it as a naked number, talismanic in its significance. In the 1930s, cosmologists calculated that the Hubble Constant was 500, and argued sharply about its meaning. Today, they engage in equally passionate, fine-grained debates about whether the true value is 67 or 73.

The hope is that applying sufficient quantitative precision to this number will yield answers to sweeping questions about humanity’s place in the cosmic order. Either we are a part of a slowly dying reality or a blip in an unfathomable eternity. The Hubble Constant could tell us which of these contradictory existential terrors awaits. »

— Corey Powell, “Fate of the Universe” in Aeon Magazine

[therealuniverse]

This video from the National Radio Astronomy Observatory describes how astronomers are measuring the current expansion of the universe and its implications for Dark Energy. This video discusses the 2 different ways that the current expansion rate of the universe has been measured, how the two numbers currently don't agree, and how gravitational waves may offer an additional way to answer this question.

[startswithabang]

The Expanding Universe Puzzle Just Got Worse, As Incompatible Answers Point To New Physics

“Could there be a problem with our local density relative to the overall cosmic density? Could dark energy change over time? Could neutrinos have an additional coupling we don't know about? Could the cosmic acoustic scale be different than the CMB data indicates? Unless some new, unexpected source of error is uncovered, these will be the questions that drive our understanding of the Universe's expansion forward. It's time to look beyond the mundane and seriously consider the more fantastic possibilities. At last, the data is strong enough to compel us.”

You’ve heard this before, commonly referred to as the “tension” in the expansion rate of the Universe. Two sets of groups are obtaining different values for how fast the Universe is expanding, and the value they get is either close to 67 km/s/Mpc (if you use an early Universe signal) or 73 km/s/Mpc (if you use a late Universe signal). A new result published this week in Science bolsters this, but a reanalysis of the one late Universe signal with a low value (of 69.8 km/s/Mpc) is the biggest deal, as improved calibrations bump that number up by ~4%, enough to put it in line with the other late Universe signals.

If neither the early nor the late group has made a mistake, the true answer is unlikely to lie in the middle. This is why, and here’s what, as a field, astrophysicists need to do about it.

[stargateatlspace]

Latest Hubble Measurements Suggest Disparity in Hubble Constant Calculations is not a Fluke

[the-telescope-times]

Astronomers use split images of quasars to produce a new estimate of the Hubble constant

Image from the Hubble Space Telescope of a doubly imaged quasar. Credit: NASA Hubble Space Telescope, Tommaso Treu/UCLA, and Birrer et al

The question of how quickly the universe is expanding has been bugging astronomers for almost a century. Different studies keep coming up with different answers—which has some researchers wondering if they've overlooked a key mechanism in the machinery that drives the cosmos.                                

Now, by pioneering a new way to measure how quickly the cosmos is expanding, a team led by UCLA astronomers has taken a step toward resolving the debate. The group's research is published today in Monthly Notices of the Royal Astronomical Society.

At the heart of the dispute is the Hubble constant, a number that relates distances to the redshifts of galaxies—the amount that light is stretched as it travels to Earth through the expanding universe. Estimates for the Hubble constant range from about 67 to 73 kilometers per second per megaparsec, meaning that two points in space 1 megaparsec apart (the equivalent of 3.26 million light-years) are racing away from each other at a speed between 67 and 73 kilometers per second.

"The Hubble constant anchors the physical scale of the universe," said Simon Birrer, a UCLA postdoctoral scholar and lead author of the study. Without a precise value for the Hubble constant, astronomers can't accurately determine the sizes of remote galaxies, the age of the universe or the expansion history of the cosmos.

Most methods for deriving the Hubble constant have two ingredients: a distance to some source of light and that light source's redshift. Looking for a light source that had not been used in other scientists' calculations, Birrer and colleagues turned to quasars, fountains of radiation that are powered by gargantuan black holes. And for their research, the scientists chose one specific subset of quasars—those whose light has been bent by the gravity of an intervening galaxy, which produces two side-by-side images of the quasar on the sky.

Light from the two images takes different routes to Earth. When the quasar's brightness fluctuates, the two images flicker one after another, rather than at the same time. The delay in time between those two flickers, along with information about the meddling galaxy's gravitational field, can be used to trace the light's journey and deduce the distances from Earth to both the quasar and the foreground galaxy. Knowing the redshifts of the quasar and galaxy enabled the scientists to estimate how quickly the universe is expanding.

Read more ~ phys.org

[cadmar]

Assumptions

Science has repeatedly demonstrated that we can not trust our observations.  We physically do not touch anything, only the electron force.  Entanglement, we are a wave and not a solid, and our notion of time.  We assume that we are the creator of all our movements, and all the movements we see around us are independent from each other and each independently creates its own movements.

What if this assumption is not correct, just as the earth is flat and the sun rotates around us?  What if all the movements are caused by the universe expanding at the speed of light?  It seems wild and crazy, but just does the flat earth and the sun rotates around us.  Is not as wild as the multi world interpretation that there are an infinite number of you in existence. 

If the movements are all caused by the expanding universe, then many, if not all, quantum paradoxes can easily be explained.

There is not one location where the universe is expanding from; for example, is the universe pushing from the right of us, or from the left of us, or from the top of us, or from the bottom of us?  No, from each point in the universe like a volcano erupting.

The movements and speed we perceive that are different from each other are due to the resistance slowing down the speed.  That is why we see the photon moving the fastest because it has no mass and hence, no resistance.  Everything that has a mass, moves against resistance.  

Burning fuel and other chemical, biological reactions and movements, again moves against a resistance and takes the path of less resistance.

In other words, from this assumption that everything moves at the same speed, follows and obeys all the laws of physics we see and tested.  

What about my mind?  I create my own movements.  Your mind has the intention which the universe pushes the neurons.  You see, our mind is connected to this living universe expanding.  

[zespaceblog]

Where did the Big Bang happen ?

The theory of the big bang was born from the observation that almost all objects in the universe appear to be moving away from each other, the acceleration of which is known as the Hubble constant. So, by rewinding time to around 14 billion years ago, we get to the point where everything burst into existence.

But where in the Universe did this happen ?

With the exception of science nerds, I could completely understand why you may not have ever asked that question, never mind thought about it today, but here you are, reading this and the question is asked, and the answer is quite likely unexpected !

What if I told you, that the big bang happened inside your head !

No, I'm most certainly not turning to Metaphysics, I actually mean inside you !! You'd be forgiven for then reasoning, "hang on, but doesn't that mean everybody who reads this too?" and the answer is Yes !

At the point of the big bang, the entire universe including the space inside you as well as outside you existed as a single point, meaning the big bang occurred everywhere, even if the things which make you up didn't exist quite at that point.

So I guess you could say, the fact the Big Bang happened in your head, really does blow your mind !