The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis, flying STS-125, HST Servicing Mission 4 - Wikipedia
Posted on 08/08/2018 11:39:48 AM PDT by ETL
Next time you eat a blueberry (or chocolate chip) muffin consider what happened to the blueberries in the batter as it was baked. The blueberries started off all squished together, but as the muffin expanded they started to move away from each other. If you could sit on one blueberry you would see all the others moving away from you, but the same would be true for any blueberry you chose. In this sense galaxies are a lot like blueberries.
Since the Big Bang, the universe has been expanding. The strange fact is that there is no single place from which the universe is expanding, but rather all galaxies are (on average) moving away from all the others. From our perspective in the Milky Way galaxy, it seems as though most galaxies are moving away from us – as if we are the centre of our muffin-like universe. But it would look exactly the same from any other galaxy – everything is moving away from everything else.
To make matters even more confusing, new observations suggest that the rate of this expansion in the universe may be different depending on how far away you look back in time. This new data, published in the Astrophysical Journal, indicates that it may time to revise our understanding of the cosmos.
Cosmologists characterise the universe’s expansion in a simple law known as Hubble’s Law (named after Edwin Hubble – although in fact many other people preempted Hubble’s discovery). Hubble’s Law is the observation that more distant galaxies are moving away at a faster rate. This means that galaxies that are close by are moving away relatively slowly by comparison.
The relationship between the speed and the distance of a galaxy is set by “Hubble’s Constant”, which is about 44 miles (70km) per second per Mega Parsec (a unit of length in astronomy). What this means is that a galaxy gains about 50,000 miles per hour for every million light years it is away from us. In the time it takes you to read this sentence a galaxy at one million light years’ distance moves away by about an extra 100 miles.
The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis, flying STS-125, HST Servicing Mission 4 - Wikipedia
This expansion of the universe, with nearby galaxies moving away more slowly than distant galaxies, is what one expects for a uniformly expanding cosmos with dark energy (an invisible force that causes the universe’s expansion to accelerate ) and dark matter (an unknown and invisible form of matter that is five times more common than normal matter). This is what one would also observe of blueberries in an expanding muffin.
The history of the measurement of Hubble’s Constant has been fraught with difficulty and unexpected revelations. In 1929, Hubble himself thought the value must be about 342,000 miles per hour per million light years – about ten times larger than what we measure now. Precision measurements of Hubble’s Constant over the years is actually what led to the inadvertent discovery of dark energy. The quest to find out more about this mysterious type of energy, which makes up 70% of the energy of the universe, has inspired the launch of the world’s (currently) best space telescope, named after Hubble.
Now it seems that this difficulty may be continuing as a result of two highly precise measurements that don’t agree with each other. Just as cosmological measurements have became so precise that the value of the Hubble constant was expected to be known once and for all, it has been found instead that things don’t make sense. Instead of one we now have two showstopping results.
On the one side we have the new very precise measurements of the Cosmic Microwave Background – the afterglow of the Big Bang – from the Planck mission, that has measured the Hubble Constant to be about 46,200 miles per hour per million light years (or using cosmologists’ units 67.4 km/s/Mpc).
On the other side we have new measurements of pulsating stars in local galaxies, also extremely precise, that has measured the Hubble Constant to be 50,400 miles per hour per million light years (or using cosmologists units 73.4 km/s/Mpc). These are closer to us in time.
Both these measurements claim their result is correct and very precise. The measurements’ uncertainties are only about 300 miles per hour per million light years, so it really seems like there is a significant difference in movement. Cosmologists refer to this disagreement as “tension” between the two measurements – they are both statistically pulling results in different directions, and something has to snap.
So what’s going to snap? At the moment the jury is out. It could be that our cosmological model is wrong. What is being seen is that the universe is expanding faster nearby than we would expect based on more distant measurements. The Cosmic Microwave Background measurements don’t measure the local expansion directly, but rather infer this via a model – our cosmological model. This has been tremendously successful at predicting and describing many observational data in the universe.
So while this model could be wrong, nobody has come up with a simple convincing model that can explain this and, at the same time, explain everything else we observe. For example we could try and explain this with a new theory of gravity, but then other observations don’t fit. Or we could try and explain it with a new theory of dark matter or dark energy, but then further observations don’t fit – and so on. So if the tension is due to new physics, it must be complex and unknown.
A less exciting explanation could be that there are “unknown unknowns” in the data caused by systematic effects, and that a more careful analysis may one day reveal a subtle effect that has been overlooked. Or it could just be statistical fluke, that will go away when more data is gathered.
It is presently unclear what combination of new physics, systematic effects or new data will resolve this tension, but something has to give. The expanding muffin picture of the universe may not work anymore, and cosmologists are in a race to win a “great cosmic bake-off” to explain this result. If new physics is required to explain these new measurements, then the result will be a showstopping change of our picture of the cosmos.
It violates the first law of thermodynamics, which says you can’t create or destroy matter or energy. Critics claim that the big bang theory suggests the universe began out of nothing. Proponents of the big bang theory say that such criticism is unwarranted for two reasons.
The first is that the big bang doesn’t address the creation of the universe, but rather the evolution of it. The other reason is that since the laws of science break down as you approach the creation of the universe, there’s no reason to believe the first law of thermodynamics would apply.
Some critics say that the formation of stars and galaxies violates the law of entropy, which suggests systems of change become less organized over time. But if you view the early universe as completely homogeneous and isotropic, then the current universe shows signs of obeying the law of entropy.
Some astrophysicists and cosmologists argue that scientists have misinterpreted evidence like the redshift of celestial bodies and the cosmic microwave background radiation. Some cite the absence of exotic cosmic bodies that should have been the product of the big bang according to the theory.
The early inflationary period of the big bang appears to violate the rule that nothing can travel faster than the speed of light. Proponents have a few different responses to this criticism. One is that at the start of the big bang, the theory of relativity didn’t apply. As a result, there was no issue with traveling faster than the speed of light. Another related response is that space itself can expand faster than the speed of light, as space falls outside the domain of the theory of gravity.
There are several alternative models that attempt to explain the development of the universe, though none of them have as wide an acceptance as the big bang theory:
The steady-state model of the universe suggests the universe always had and will always have the same density. The theory reconciles the apparent evidence that the universe is expanding by suggesting that the universe generates matter at a rate proportionate to the universe’s rate of expansion.
The Ekpyrotic model suggests our universe is the result of a collision of two three-dimensional worlds on a hidden fourth dimension. It doesn’t conflict with the big bang theory completely, as after a certain amount of time it aligns with the events described in the big bang theory.
The big bounce theory suggests our universe is one of a series of universes that first expand, then contract again. The cycle repeats after several billion years.
Plasma cosmology attempts to describe the universe in terms of the electrodynamic properties of the universe. Plasma is an ionized gas, which means it’s a gas with free roaming electrons that can conduct electricity.
There are several other models as well. Could one of these theories (or other ones we haven’t even thought of) one day replace the big bang theory as the accepted model of the universe? It’s quite possible. As time passes and our capability to study the universe increases, we’ll be able to make more accurate models of how the universe developed.
https://science.howstuffworks.com/dictionary/astronomy-terms/big-bang-theory7.htm
The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to sometime between 10−33 and 10−32 seconds after the singularity.
Following the inflationary period, the universe continues to expand, but at a less rapid rate.[1]
Inflation theory was first developed in 1979 by theoretical physicist Alan Guth at Cornell University.
It was developed further in the early 1980s. It explains the origin of the large-scale structure of the cosmos.
Quantum fluctuations in the microscopic inflationary region, magnified to cosmic size, become the seeds for the growth of structure in the Universe (see galaxy formation and evolution and structure formation).[2]
Many physicists also believe that inflation explains why the universe appears to be the same in all directions (isotropic), why the cosmic microwave background radiation is distributed evenly, why the universe is flat, and why no magnetic monopoles have been observed.
The detailed particle physics mechanism responsible for inflation is unknown.
The basic inflationary paradigm is accepted by most physicists, as a number of inflation model predictions have been confirmed by observation;[3] however, a substantial minority of scientists dissent from this position.[4][5][6]
The hypothetical field thought to be responsible for inflation is called the inflation.[7]
In 2002, three of the original architects of the theory were recognized for their major contributions; physicists Alan Guth of M.I.T., Andrei Linde of Stanford, and Paul Steinhardt of Princeton shared the prestigious Dirac Prize "for development of the concept of inflation in cosmology".[8]
In 2012, Alan Guth and Andrei Linde were awarded the Breakthrough Prize in Fundamental Physics for their invention and development of inflationary cosmology.[9]
The model describes how the universe expanded from a very high-density and high-temperature state,[5][6] and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background (CMB), large scale structure and Hubble's law.[7]
If the known laws of physics are extrapolated to the highest density regime, the result is a singularity which is typically associated with the Big Bang.
Physicists are undecided whether this means the universe began from a singularity, or that current knowledge is insufficient to describe the universe at that time.
Detailed measurements of the expansion rate of the universe place the Big Bang at around 13.8 billion years ago, which is thus considered the age of the universe.[8]
After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms.
Giant clouds of these primordial elements later coalesced through gravity in halos of dark matter, eventually forming the stars and galaxies visible today.
Since Georges Lemaitre first noted in 1927 that an expanding universe could be traced back in time to an originating single point, scientists have built on his idea of cosmic expansion.
The scientific community was once divided between supporters of two different theories, the Big Bang and the Steady State theory, but a wide range of empirical evidence has strongly favored the Big Bang which is now universally accepted.[9]
In 1929, from analysis of galactic redshifts, Edwin Hubble concluded that galaxies are drifting apart; this is important observational evidence consistent with the hypothesis of an expanding universe.
In 1964, the cosmic microwave background radiation was discovered, which was crucial evidence in favor of the Big Bang model,[10] since that theory predicted the existence of background radiation throughout the universe before it was discovered.
More recently, measurements of the redshifts of supernovae indicate that the expansion of the universe is accelerating, an observation attributed to dark energy's existence.[11]
The known physical laws of nature can be used to calculate the characteristics of the universe in detail back in time to an initial state of extreme density and temperature.[12]"
Scientists have finally discovered why the Universe
is expanding...It’s trying to get away from Chuck Norris.
What is it expanding in to?................
now...tell me another one!
************************
;)
+++++
Click, Click....Click, Click....??????
*************
It seems to me that the universe is expanding at the rate of the next waist size in pants every year.
Can you imagine how much cloth you would need to make a pair of pants for the universe?
“Galaxies are a lot like blueberries”
Galaxies need sugar and whipped cream?
“Galaxies are like blueberries”
No they’re not.
They’re like cocktail weenies.
This is old news.
If the universe is indeed expanding, then why aren’t my pants?
(Seen in a cartoon way back when)
According to most 'experts', nothing. The Universe is everything. Others think there may be multiple universes.
Yeah, about 13.7 billion years old.
” the laws of science break down”
NO. The laws of science are inadequate to explain what happens as you approach the creation of the Universe.
Revise the laws of science. Oh, you can’t?
My previous post was a joke :)
Here’s a guy who doesn’t mix the blueberry sauce into the muffin mix telling us about the universe.
Isn’t there some kind of law against explaining the universe until you’ve made a decent batch of blueberry muffins?
If not, there should be.
They can't come close to fully explaining what's going on in the present, neither on the grand scale, or quantum realm. Many major mysterious remain.
Mmmmmmm......
I like my Galaxies with some coffee.
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