-
---------------------- 2712 - UNIVERSE - the mysterious universe we live in?
-
- The distances don’t make it any easier. The moon is the closest to earth. 384,400 kilometers away, or, 1.282 light seconds away. The moon we see, is always around 1 second in the past. That is only a slight distortion.
-
- The farthest galaxy observed is 13.4 billion lightyears from Earth. That doesn’t mean it is that many light years away. Instead, it is probably more than 30 billion light years away now due to the accelerating expansion of the universe.
-
- The galaxy we see is as it was 400 million years after the Big Bang. The light has been traveling for 13 billion years to reach us. Most of what we see in the sky, is the past.
-
- Our Milky Way galaxy is part of the 100 to 200 billion galaxies that we estimate exist in the observable universe. There are definitely parts of the universe that have expanded away from us and the light has not had enough time to reach us.
-
- All the matter that we do see, including all those galaxies, make up only 5 percent of the universe. If that isn’t strange enough, we do not know what the other 95 percent of it is!
-
- According to Newton, gravity weakens as you go further from the center and the object moves slower. Stronger the pull, faster the movement. We see this in our solar system. This is why Mercury takes 87 days to go around the Sun once while Neptune takes 165 years.
-
- Stars at edge of galaxies rotate just as fast as the ones near the center. There is not nearly enough mass in the galaxies to cause this effect so astronomers came to the conclusion that there was something massive causing the gravitational field to extend and keep the stars moving just as fast. Something we couldn’t see, hence the term, dark matter. It makes up 25% of the universe‘s matter/energy.
-
- We can’t see it but we measure its effects. It only interacts gravitationally. And so, some theories suggest maybe we don’t understand gravity and dark matter doesn’t really exist. Either way, behavior of galaxies and the motion of the stars in it, tells us we are missing something.
-
- We have found the Dragonfly 44 galaxy, which is 99 percent dark matter. We have also found a galaxy with no dark matter in it. The fascinating thing is that the galaxy with no dark matter strengthens the case that dark matter, whatever it may be, exists. But as of today, it still remains a mystery.
-
- The universe has been expanding since it all began but how does it end? Knowing the amount of matter and its gravity and the rate at which parts of the universe are expanding, we can answer this question. In a sense, it’s a fight between the expansion of the space and gravity of the matter in it. And expansion wins.
-
- There’s not enough matter in the universe for the gravity to reverse the expansion. So it will go on. We assumed that at some point, this expansion would slow down and stop. When it was actually measured though, it was shocking to see that the expansion was actually speeding up.
-
- It’s quite strange because there doesn’t seem to be a reason for this to be happening. If space was expanding at a constant rate, it would not have turned many heads. Slowing down of the expansion was what we expected. But something was making it go faster than it was in the past. The cause of this accelerating expansion has come to be called dark energy.
-
- Other than knowing that it must be a property of empty space itself, we don’t know too much about it. It makes up 70 percent of the universe. The biggest part of it. And as it stands it will continue to grow exponentially. Which means in a distant future, it will be a very dark universe.
-
- Solving the unanswered questions in science may or may not lead to a deeper understanding of the precise nature of reality. The universe makes you feel small, insignificant and gives you an existential crisis. At its best, makes you feel like a child in front of a giant puzzle. Somewhere in the middle of that large spectrum is where we find our existence.
-
- The universe as we know it began 13.8 billion years ago. This moment, known as the Big Bang, is when space itself rapidly began expanding. At the time of the Big Bang, the observable universe (including the materials for at least 2 trillion galaxies), fit into a space less than a centimeter across. Now, the observable universe is 93 billion light-years across and still expanding.
-
- Until 1929, the origins of the universe were shrouded entirely in myth and speculation. But that year, an enterprising astronomer named Edwin Hubble discovered something very important about the universe, something that would open up new ways of understanding its past: The whole thing is expanding.
-
- Hubble made his discovery by measuring redshift of the light spctrum, which is the shift toward longer, red wavelengths of light seen in very distant galaxies. The farther away the object, the more pronounced the redshift. Hubble found that redshift increased linearly with distance in far-off galaxies, indicating that the universe isn't stationary. It's expanding, everywhere, all at once.
-
- Hubble was able to calculate the rate of this expansion, a figure known as the “Hubble Constant“. Today “Ho” is believed to be 49,300 miles per hour per million lightyears distance. It was this discovery that allowed scientists to extrapolate back and theorize that the universe was once packed into a tiny point. They called the first moment of its expansion the Big Bang.
-
- In May 1964, Arno Penzias and Robert Wilson, researchers at Bell Telephone Laboratories, were working on building a new radio receiver in New Jersey. Their antenna kept picking up a strange buzzing that seemed to come from everywhere, all the time. They thought it might be pigeons in the equipment, but removing the nests did nothing. Neither did their other attempts to reduce interference. Finally, they realized they were picking up something real.
-
- What they'd detected, it turned out, was the first light of the universe, the “cosmic, microwave background radiation“. This radiation dates back to about 380,000 years after the Big Bang, when the universe finally cooled enough for photons (the wave-like particles that make up light) to travel freely.
-
- The discovery lent support to the Big Bang theory and to the notion that the universe expanded faster than the speed of light in its first instant. The cosmic background is uniform and suggests a smooth expansion of everything at once from a small point.
-
- This discovery of the cosmic microwave background opened a window into the origins of the universe. In 1989, NASA launched a satellite called the Cosmic Background Explorer, which measured tiny variations in the background radiation. The result was a "baby picture" of the universe which shows some of the first density variations in the expanding universe. These miniscule variations probably gave rise to the pattern of galaxies and empty space, known as the “cosmic web of galaxies“, that we see in the universe today.
-
- The cosmic microwave background also enabled researchers to find the massive, faster-than-light expansion that occurred at the Big Bang. (Although Einstein’s theory of special relativity holds that nothing goes faster than light through space, this wasn’t a violation; space itself expanded.)
-
- In 2016, physicists announced that they had detected a particular kind of polarization, or directionality, in some of the cosmic microwave background. This polarization is known as "B-modes."
-
- The B-mode polarization was the first-ever direct evidence of gravitational waves from the Big Bang. Gravitational waves are created when massive objects in space speed up or slow down (the first that were ever discovered came from the collision of two black holes). The B-modes provide a new way to directly probe the early universe's expansion.
-
- One consequence of the gravitational-wave discovery was that it allowed scientists to search for additional dimensions, beyond the usual three. According to theorists, gravitational waves should be able to cross into unknown dimensions, if those dimensions exist.
-
- Later, in October 2017, scientists detected gravitational waves from the collision of two neutron stars. They measured the time it took the waves to travel from the stars to Earth, and found no evidence of any extra-dimensional leakage.
-
- The results suggest that if there are any other dimensions out there, they're tiny. They would affect areas of the universe less than 1 mile in size. That means that string theory, which posits that the universe is made of tiny vibrating strings and predicts at least 10 teensy dimensions, could still be true.
-
- One of the strangest discoveries in physics is that the universe is not only expanding, it's expanding at an accelerating rate.
-
- The discovery dates back to 1998, when physicists announced the results of several long-running projects that measured particularly heavy supernovas called Type Ia supernovas. The results revealed weaker-than-expected light from the most distant of these supernovas. This weak light showed that space itself is expanding making the detected light dimmer. Everything in the universe is gradually getting farther away from everything else.
-
- Scientists call the driver of this expansion "dark energy," a mysterious engine that could make up about 70% of the energy in the universe. This dark energy seems to be crucial to making theories of the beginning of the universe fit observations that are being conducted now, such as those made by NASA's Wilkinson Microwave Anisotropy Probe, an instrument that has produced the most precise map of the cosmic microwave background yet.
-
- Results from the Hubble Telescope, released in April 2019, have deepened the puzzle of the expanding universe. The measurements from the space telescope show that the universe's expansion is 9% faster than expected from previous observations. For galaxies, every 3.3 million light-years' distance from Earth translates to an additional 46 miles per second faster than earlier calculations predicted.
-
- Why does this matter for the origins of the universe? Because physicists must be missing something. There may have been three separate dark energy "bursts" during the Big Bang and shortly thereafter. Those bursts set the stage for what we see today.
-
- The first might have started the initial expansion; a second may have happened much faster causing the universe to expand faster than previously believed. A final dark energy burst may explain the accelerating expansion of the universe today.
-
- The Hobby-Eberly Telescope Dark Energy Experiment, is measuring the faint light from galaxies as far away as 11 billion light-years, which will allow researchers to see any changes in the universe's acceleration over time.
-
- They will be studying the echoes of disturbances in the 400,000-year-old universe, created in the dense soup of particles that made up everything right after the Big Bang. They hope this will reveal the mysteries of expansion and explain the dark energy that drove it.
-
- Stay tuned there is much more to learn.
-
- April 19, 2020 2712 ----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to whomever is interested. ----
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for copies or Index of all reviews
--- to: ------ jamesdetrick@comcast.net ------ “Jim Detrick” -----------
- https://plus.google.com/u/0/ -- www.facebook.com -- www.twitter.com
--------------------- Sunday, April 19, 2020 -------------------------
-----------------------------------------------------------------------------------------
No comments:
Post a Comment