COSMOLOGICAL CONSTANT - expanding the Universe?

 -  2797  -  COSMOLOGICAL  CONSTANT  -  expanding the Universe?  The Universe is not only expanding its expansion is accelerating at an ever faster rate.  Now, science is resurrecting the cosmological constant in order to use Einstein’s equations to explain an accelerating expansion that began 5 billion years ago.  

---------------  2797  - COSMOLOGICAL  CONSTANT  -  expanding the Universe?

-   In 1917 Albert Einstein completed his equations for General Relativity and a new theory for gravity.  He recognized that a problem with his equations required the contraction or the expansion of the Universe but not the static condition that everyone thought existed at the time.  So, Albert added a “cosmological constant”, a factor in the equations that allowed the Universe to exactly balance and remain static.

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-  In 1929 Edwin Hubble proved to Albert that the remote galaxies were accelerating away from us.  The further away the faster galaxies receded.  The Universe was expanding, it was not static.  Albert said the cosmological constant was the greatest blunder of his life.

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-  Today, we are not so sure it was a blunder.  We know the Universe is not only expanding its expansion is accelerating at an ever faster rate.  Now, science is resurrecting the cosmological constant in order to use Einstein’s equations to explain an accelerating expansion that began 5 billion years ago. 

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-   Dark Energy, a form of anti-gravity, a repulsive force,  started becoming more dominate than Dark Matter, and all matter / energy that creates gravity, an attractive force, 5 billion years ago.  Gravity decreases with distance.  Dark Energy and anti-gravity are constant in all space. 

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-   Therefore, Dark Energy becomes more and more dominate as the Universe continues to expand.  Its rate of expansion gets faster and faster.  Science can rearrange Einstein’s equation and insert the cosmological constant back in and get this observed affect in the Cosmos.

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-  Einstein’s original idea in creating his equations was to define gravity so gravity and accelerated motion were equivalent.  Without an outside reference you can not tell the difference between acceleration and gravity.  Einstein’s equation had the Universe as static with no boundaries but curved back on itself like the surface of a balloon.  

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-  The cosmological constant term in the equation produced a cosmic repulsion on large scales enough that would just counteract gravitational attraction on large scales.  Without the cosmological constant in the equation there is no term to counteract gravity and the Universe would collapse on itself.  With the term small enough the Universe would expand but gravity simply continuously slows the expansion into infinity.

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-  Einstein’s original equation related the curvature of space to the distribution of matter and energy.  When he added the Constant he put it on the left side of the equation suggesting it was a property of space itself.  

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-  Today science wants to put the Constant on the right side of the equation and suggest that it represents a new form of energy density.  The Constant remains constant as space expands and eventually dominates gravity’s attraction that decreases with distance.

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-  Since 1998 evidence  from supernovae explosions have convinced astronomers that over the past 5,000,000,000 years the expansion of the Universe has been speeding up.  Supernovae explosion were dimmer than expected which meant they were further away than expected because the Universe was expanding faster than expected.

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-  Since 2000 the measurement of the angular size of the small variations in the Cosmic Microwave Background radiation have convinced astronomers that the geometry of the Universe is flat.  It is not a positive curvature like the balloon shape as Einstein thought.  

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-  For the Universe to be geometrically flat the average matter / energy density must be equal to the Critical Density.  The “Critical Density” is where the balance occurs between expansion and contraction.  When astronomers measure all forms of matter / energy in the Universe they come up with only 5% of the amount needed.   We were missing 95% with what we could see. 

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-   When they add “Dark Matter’ they can get up to 27% of what is needed.  For the Universe to be flat and accelerating as it is there must be 73% Dark Energy, vacuum energy that is repelling gravity.  It is in the vacuum of space. 

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-   The problem now is how do we measure the weight of “nothing” when it makes up 73% of everything?

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-  So, what we are left with to date is a flat Universe dominated by positive vacuum energy that will expand the Universe forever at an ever increasing rate.  How do you explain this?

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-  Our knowledge usually develops in an atmosphere of creative confusion.  I, at least, have the confusion part right!

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-  August 24, 2020                              1126                                         2797                                                                                                                                                 

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 ---------------------   Monday, August 24, 2020  -------------------------

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INFLATION - the ever expanding Universe?

-  2796  -  INFLATION  -  the ever expanding Universe?  -   The Universe is expanding.  Space is growing.  All the galaxies are separating farther and farther apart.  The greater the distance between the galaxies the faster they are separating because there is more expanding space in between them.  This repulsive force of expansion is a very weak force, much, much weaker than the force of gravity. 

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--------------------------  2796 -  INFLATION  -  the ever expanding Universe?

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-  The velocity of the expansion of space and therefore the velocity of the separation of the galaxies is only 0.047 miles per hour per lightyear separation. ( This is called the Hubble Constant = Ho = 70 km/sec/mega parsec ,  or also:  22,000  meters/sec/million lightyears) 

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-  This velocity equates to 248 feet per hour per lightyear.   Very slow, however, if two galaxies are 1 billion lightyears apart this small velocity translates to 47,000,000 miles per hour rate of separation. 

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-  Light, all electromagnetic radiation, and gravity travel at the constant speed of 670,633,500 miles per hour.  Therefore, the two galaxies are separating at 7% the speed of light.  The more they separate the faster they go.  Once two galaxies are separating faster than the speed of light they can no longer see each other.

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-  The force of gravity is much stronger but gravity only comes as a function of mass.  And, there is a lot more space out there than there is mass.  Secondly, the attractive force of gravity falls off at the inverse square of distance.  The greater the distance the weaker the gravity.  This is not the case with the expanding force of the vacuum of space.  The repulsive force always remains constant ( 0.047 mph/lightyear) regardless of distance and wherever in the Universe.

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-  Astronomers do not understand what is causing the expansion, or what creates this repulsive force.  It is a form of anti-gravity.  It is going on now and it was going on even more rapidly in the early Universe. 

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-  Up until a few years ago most astronomers believed that the expansion of the Universe would be slowing down due to the incessant  pull of gravity.  Now astronomers believe the Universe is dominated by the repulsive force and the Universe is expanding at an ever increasing rate.  They call it “Dark Energy“, the repulsive force in the vacuum of space that is accelerating the expansion of the Universe.

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-  Astronomers believe that expanding space at one time in the early Universe had a velocity greater than the speed of light.  This rapid inflation would account for the characteristics of homogeneity, uniformity, isotropy, and flatness that we observe in the current Universe. 

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-   Cosmic Inflation is believed to have been caused by the “freezing” out of the Strong Nuclear Force from the Electromagnetic and Weak Nuclear forces.  Gravity had already “froze” out at 10^-43 seconds after the Big Bang at a temperature of 10^32 Kelvin.  The Strong Force at 10^-35 seconds and 10^27 Kelvin and the Weak Nuclear Force at 10^-12 seconds and 10^12 Kelvin.  

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-   The Strong Nuclear Force separation released enormous energy causing the Universe to expand in less than 10^-36 seconds.  Much faster than the speed of light to a factor of 10^30 times greater in size.  1,000,000,000,000,000,000,000,000,000,000 times larger in an instant.  The idea here is that space went through a phase change like water changing from liquid to solid ice.  Super cooled water can crystallize to ice in an instant in every direction.  Inflation happened like that.

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-  Quantum fluctuations in the early Universe’s primordial soup of particles, waves and energies grew into denser regions and rarified regions in space as space expanded.  These denser regions with the help of gravity grew into Black Holes, stars, and galaxies.  In this way Cosmic Inflation explains the way we see the Universe today.  A tiny ripple in space smaller than the size of an atomic nucleus grew into a density wave the size of our Solar System.  Gravity pulled these denser regions into galaxies.

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-  Astronomers can see with their telescopes about 10 billion lightyears distance today.  Theoretically, astronomers can never see beyond 13.7 billion lightyears because that is when light was first created  and that is as far as light could have traveled up to this time.

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-    “Cosmic Inflation’ explains the smoothness and uniformity of the Universe.  It explains why the observable Universe is the same density and the same temperature looking east 10 billion lightyears and looking west 10 billion lightyears while the two regions are 20 billion lightyears apart and could not be the same temperature unless they were once in contact and then separated faster than the speed of light.

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-  When Cosmic Inflation started the universe was 10^-35 seconds old, the two regions were 10^-35 lightyears away from one another.  Before Inflation started light could bounce between the two regions and equalize their temperatures and densities.  So that explains the uniformity of the Universe.

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-  Cosmic Inflation also explains why the Universe appears nearly “flat”.  The expansion rate is very small in Cosmic terms.  It is almost balanced with the Universe’s force of gravity attraction rate.  It is very near the balancing point.

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-    The Universe contains nearly the “Critical Density” needed to balance gravity attraction with the Dark Energy’s repulsion.  If the density of the University were a little greater in the beginning the Universe would have collapsed back on itself due to gravity long ago.

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-    If the density were a little less in the beginning the Universe would have expanded so fast spreading matter so thin that galaxies would have never formed.  Somehow the Universe started with the density just right to form the galaxies as we see them today.

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-  Of course, there is still a problem.  All the matter that astronomers can find with radiation and gravity wave telescopes in the Observer able Universe can only account for 25% of the Critical Density. 

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-   But, if the Universe is truly “flat” the additional density must be there, somewhere.  That is where astronomers come up with 75% of the Universe being made of Dark Energy, using Einstein’s equivalence of energy = mass times (speed of light)^2.  In order to get to a “flat “ Universe the total density of matter, including Dark Matter, and Dark Energy together must nearly equal the “Critical Density”.

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-  Confirmation of these ideas comes from studying the Cosmic Microwave Background (CMB) radiation which has temperature differences of 1/100,000th of a degree around an average 2.73 degrees Kelvin separated by about 1 degree of arc.

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-    These measurements of the Universe’s radiation when it was 380,000 years old are consistent with a flat Universe , uniform yet with still enough structure to form the galaxies.  When the waves in the CMB were studied in detail the density of the Universe was put at 4.4% ordinary matter, 23% Dark Matter, and 73% Dark Energy.

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- How can you measure the expansion of space since it has to be expanding relative to something?   One thing we can use is to measure expansion relative to the CMB radiation.

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-    For example:  our Milky Way is moving 1,342,000 miles per hour relative to the CMB radiation.  To get to this you have to separate two types of motion.  The motion within the influence of gravity which can not exceed the speed of light.  And, the motion in the influence of the expansion of space which can exceed the speed of light. 

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-   Astronomers have to subtract the motion of the Earth orbiting the Sun, and the Sun orbiting the center of the Milky Way galaxy, and the Milky Way Galaxy gravity pulled toward the galaxy cluster.  The motion that is left is the motion due to the expansion of space moving us 1,342,000 miles per hour relative to the Cosmic Microwave Background.

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-  The Andromeda Galaxy and the Milky Way Galaxy are gravity bound and moving towards each other at 673,318 miles per hour.  But, the space expanding between the two galaxies is expanding at the rate of 0.047 miles per hour per lightyear.  Andromeda should be moving away at 131,520 miles per hour due to expanding space.  At the same time gravity is pulling the galaxies together at 673,318 miles per hour. 

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-   So, is expanding space slowing this closure rate down?  No.  The 673,318 miles per hour closure rate is with the expanding space.  The idea here is that gravity is much, much stronger attraction than expansion’s repulsion. 

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-   Andromeda is like a race car coming towards us and the velocity of the wind is blowing it backwards.  The velocity of the wind does not subtract from the velocity of the car.  The velocity of the wind has almost no affect.  The only way the repulsive force would be a factor is if the galaxies were much, much farther apart.  Gravity would be much, much weaker and a balancing point exists beyond which space expansion and repulsion would take over as the stronger force.

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-  August 23, 2020                               849                                          2796                                                                                                                                                 

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 ---------------------   Sunday, August 23, 2020  -------------------------

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INFLATION - how the Universe began

 -  2795  - INFLATION  -   how the Universe began.  Where did all of this Universe come from?  The idea that we could find the answers by examining the Universe itself was foreign until recently, when scientific measurements began to solve the puzzles that had stymied philosophers, theologians, and thinkers alike throughout our history.

--------------------------  2795  - INFLATION  -   how the Universe began

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- The 20th century brought us General Relativity, quantum physics, and the Big Bang, all accompanied by spectacular observational and experimental successes. These frameworks enabled us to make theoretical predictions that we then went out and tested, and they passed with flying colors while the alternatives fell away.

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-  Looking back to greater distances means looking back in time.  The Moon is  1½ seconds older than when we see it .  The Sun is 8 minutes older.  The neasest star is 41/2 years older than when we see it.  The further we look the further back in time we see.

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-  In the 1920s, just under a century ago, our conception of the Universe changed forever as two sets of observations came together in perfect harmony. Scientists had begun to measure spectral lines,  emission and absorption spectral lines, of a variety of stars and nebulae. 

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-  Because atoms are the same everywhere in the Universe, the electrons within them make the same transitions: they have the same absorption and emission spectra. But a few of these nebulae, the spirals and ellipticals in particular, had extremely large redshifts that corresponded to high recession speeds: faster than anything else in our galaxy.

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-  Remember the further the distance the more the light’s wavelength of light is stretched out from the visible to the infrared.  The expanding space stretches the light and lessens its energy.

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-  Starting in 1923, Edwin Hubble and Milton Humason began measuring individual stars in these nebulae, determining the distances to them. They were far beyond our own Milky Way: millions of light-years away in most instances. 

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-  When you combined the distance and redshift measurements together, it all pointed to one inescapable conclusion that was also theoretically supported by Einstein’s General theory of Relativity: the Universe was expanding. The farther away a galaxy is, the faster it appears to recede from us.  The longer the wavelength of light.

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-  If the Universe is expanding today, that means that all of the following must be true.

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-----------------------    The Universe is getting less dense, as the (fixed amount of) matter in it occupies larger and larger volumes.

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-----------------------    The Universe is cooling, as the light within it gets stretched to longer wavelengths.

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-----------------------    Galaxies that aren’t gravitationally bound together are getting farther apart over time.

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-  Those are some remarkable and mind-bending facts, as they enable us to extrapolate what’s going to happen to the Universe as time marches inexorably forwards. But the same laws of physics that tell us what’s going to happen in the future can also tell us what happened in the past, and the Universe itself is no exception.

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-----------------------   If the Universe is expanding, cooling, and getting less dense today, that means it was smaller, hotter, and denser in the distant past.

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-   The big idea of the Big Bang was to extrapolate this back as far as possible: to ever hotter, denser, and more uniform states as we go earlier and earlier. This led to a series of remarkable predictions:

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-----------------------    More distant galaxies should be smaller, more numerous, lower in mass, and richer in hot, blue stars than their modern-day counterparts,

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-----------------------    There should be fewer and fewer heavy elements as we look backwards in time,

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-----------------------    There should come a time when the Universe was too hot to form neutral atoms (and a leftover bath of now-cold radiation that exists from that time),

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------------------------    There should even come a time where atomic nuclei were blasted apart by the ultra-energetic radiation (leaving a relic mix of hydrogen and helium isotopes).

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-  All four of these predictions have been observationally confirmed, with that leftover bath of radiation and now called the cosmic microwave background, discovered in the mid-1960s.

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-  We can extrapolate the Big Bang all the way back, arbitrarily far into the past, until all the matter and energy in the Universe is concentrated into a single point. The Universe would reach infinitely high temperatures and densities, creating a physical condition known as a “singularity.  However all the laws of physics as we know them give predictions that no longer make sense and cannot be valid anymore.

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-  Our conclusions are that the Universe began with a Big Bang some finite time ago, corresponding to the birth of space and time, and that everything we’ve ever observed has been a product of that aftermath.

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-   We had a scientific answer that truly indicated not only that the Universe had a beginning, but when that beginning occurred. 

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-  Only, there were a number of unresolved puzzles that the Big Bang posed, but presented no answers for.

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------------------------      Why did regions that were causally disconnected  i.e., had no time to exchange information, even at the speed of light have the same temperatures as one another?

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------------------------      Why were the initial expansion rate of the Universe (which works to expand things) and the total amount of energy in the Universe (which gravitates and fights the expansion) perfectly balanced early on: to more than 50 decimal places?

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------------------------      Why, if we reached these ultra-high temperatures and densities early on, are there no leftover relic remnants from those times in our Universe today?

-  Throughout the 1970s, the top astrophysicists in the world worried about these problems, theorizing about possible answers to these puzzles. Then, in late 1979, a young theorist named Alan Guth had a spectacular realization that changed history.

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-  The 3 big puzzles, the horizon, flatness, and monopole problems, that inflation solves.

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-  The new theory was known as cosmic inflation, and postulated that perhaps the idea of the Big Bang was only a good extrapolation back to a certain point in time, where it was preceded (and set up) by this inflationary state. Instead of reaching arbitrary high temperatures, densities, and energies, inflation states that:

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-----------------------  The Universe was no longer filled with matter and radiation, but,  instead possessed a large amount of energy intrinsic to the fabric of space itself, which caused the Universe to expand exponentially (where the expansion rate doesn’t change over time),

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-----------------------    Which drives the Universe to a flat, empty, uniform state, until inflation ends. When it ends, the energy that was inherent to space itself  the energy that’s the same everywhere, except for the quantum fluctuations imprinted atop it gets converted into matter and energy, resulting in a hot Big Bang.

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-  This was a brilliant leap, because it offered a plausible physical explanation for the observed properties the Big Bang alone could not account for. Causally disconnected regions have the same temperature because they all arose from the same inflationary “patch” of space.

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-  The expansion rate and the energy density were perfectly balanced because inflation gave that same expansion rate and energy density to the Universe prior to the Big Bang. 

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-  And, there were no left over, high-energy remnants because the Universe only reached a finite temperature after inflation ended.

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-  In fact, inflation also made a series of novel predictions that differed from that of the non-inflationary Big Bang, meaning we could go out and test this idea. As of today, in 2020, we’ve collected data that puts four of those predictions to the test:

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------------------------      The Universe should have a maximum, non-infinite upper limit to the temperatures reached during the hot Big Bang.

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-----------------------    Inflation should possess quantum fluctuations that become density imperfections in the Universe that are 100% adiabatic (with constant entropy).

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-----------------------    Some fluctuations should be on super-horizon scales: fluctuations on scales larger than light could have traveled since the hot Big Bang.  Those fluctuations should be almost, but not perfectly, scale-invariant, with slightly greater magnitudes on large scales than small ones.

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-----------------------    The fluctuations from inflation get stretched across the Universe, creating overdensities.

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-  With data from satellites like COBE, WMAP, and Planck, we’ve tested all four, and only inflation yields predictions that are in line with what we’ve observed. 

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-  But this means that the Big Bang wasn’t the very beginning of everything; it was only the beginning of the Universe as we’re familiar with it. Prior to the hot Big Bang, there was a state known as “cosmic inflation“, that eventually ended and gave rise to the hot Big Bang, and we can observe the imprints of cosmic inflation on the Universe today.

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-  But only for the last tiny, minuscule fraction of a second of inflation. Only, perhaps, for the final ~10-33 seconds of it can we observe the imprints that inflation left on our Universe. 

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-  It’s possible that inflation lasted for only that small duration. It’s possible that the inflationary state was eternal, or that it was transient, arising from something else. It’s possible that the Universe did begin with a singularity, or arose as part of a cycle, or has always existed. But that information doesn’t exist in our Universe. Inflation by its very nature erases whatever existed in the pre-inflationary Universe.

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-  In many ways, inflation is like pressing the cosmic “reset” button. Whatever existed prior to the inflationary state, if anything, gets expanded away so rapidly and thoroughly that all we’re left with is empty, uniform space with the quantum fluctuations that inflation creates superimposed atop it.

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-   When inflation ends, only a tiny volume of that space, somewhere between the size of a soccer ball and a city block, will become our observable Universe. Everything else, including any of the information that would enable us to reconstruct what happened earlier in our Universe’s past, now lies forever beyond our reach.

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-  It’s one of the most remarkable achievements of science of all: that we can go back billions of years in time and understand when and how our Universe, as we know it, came to be this way.

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-  But like many adventures, revealing those answers has only raised more questions. The puzzles that have arisen this time, however, may truly never be solved. If that information is no longer present in our Universe, it will take a revolution to solve the greatest puzzle of all: where did all this come from?????????????????????????????    

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------------------------------------  Other reviews available:

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-    2780  - INFLATION  -  an expanding universe?  -   The Universe is expanding.  Space is growing.  All the galaxies are separating away from each other.  The greater the distance between the galaxies the faster they are separating because there is more expanding space in between them.     

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-  2212  -  How the Universe began?   In 1980 the theory of Inflation was put forth by Alan Guth to explain the uniformity and isotropic nature of the Universe today.  In order for the Universe to be uniform when looking 13.8 billion light years in one direction and the same 13.8 billion light years in he opposite direction the universe must have expanded faster than the speed of light.  

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-  2144.

-  August 22, 2020                                                                             2795                                                                                                                                                 

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-----  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”  -----------

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 ---------------------   Sunday, August 23, 2020  -------------------------

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Index of recent reviews:

 -  Index of recent Reviews available upon request:

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-  2773 -  FINE  STRUCTURE  CONSTANT  -  The fine structure constant is a measure of electromagnetism and it is one of the four fundamental forces in nature (the others are gravity, weak nuclear force and strong nuclear force).  The fine structure constant is the quantity that physicists use as a measure of the strength of the electromagnetic force.

-  2774  - MARS  -  the first helicopter flight?  See Review 2772 to learn about missions to Mars and this latest mission scheduled for next month, August 2020.  This review is about the helicopter that is hitching a ride and will deploy when Rover lands on the planet in February, 2021.

-  2775 -  LIGHT -  why the constant speed?  The speed of light is 299,792,458 meters per second.  But why does it have the value that it does? Why isn't it some other number? And why do we care so much about some random speed of electromagnetic waves? Why did it become such a cornerstone of physics?

-  2776  -  MARS - 4th rock from the sun.   Mars is the forth rock from the Sun and is the easiest planet for us to get to.  Since 2007 we have 3 satellites orbiting Mars and 2 robots roving around the surface.  The robots take pictures and run tests on the soil sending the data up to the satellite overhead to be relayed back to Earth.  

-  2777  -  EYE  -  a prosthetic eye for artificial vision? -  In 2005 a medical team invented a prosthetic eye, artificial vision, for the blind.  Many people are blind due to a medical condition where the eye has deteriorated photo sensors in the back of the retina.   In 2020 bionic eye technology is in its infancy but it will do more than prosthetic eyes.  Bionic eye implants work inside the existing eye structures or in the brain. They are designed to achieve functional vision.

-  2778 -  INFRARED  ASTRONOMY  -  new discoveries from an airplane.   Ten years ago, NASA’s telescope on an airplane, the “Stratospheric Observatory for Infrared Astronomy“, or SOFIA, became operational. Since May, 2010, SOFIA’s observations of infrared light, invisible to the human eye, have made many scientific discoveries about the hidden universe.

-  2779  -  PLANCK  -  microwave background radiation.  The Cosmic Microwave Background (CMB)  observed by the Planck satellite is a snapshot of the oldest light in our Universe.  It was imprinted on the sky when the Universe was just 380,000 years old. The imprint shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure that being the stars and galaxies of today. 

-  2780  - INFLATION  -  an expanding universe?  -   The Universe is expanding.  Space is growing.  All the galaxies are separating away from each other.  The greater the distance between the galaxies the faster they are separating because there is more expanding space in between them. 

-  2782  -  KUIPER  BELT  -  Name the Tenth Planet?  -  There are some conflicting opinions whether the 10th planet should be called a “planet”.  Maybe it should be called a large asteroid, or comet?  All the objects found beyond the orbit of Neptune are called Kuiper Belt Objects, KBO‘s .  Named after Peter Gerard  Kuiper, 1905 - 1973.  

-  2783  - MARS  -  launch of Perseverance mission.  -  NASA's Mars 2020 Perseverance rover mission is on its way to the Red Planet to search for signs of ancient life and collect samples to send back to Earth.  Humanity's most sophisticated rover launched July, 2020.

-  2784  -  UNIVERSE -  measuring age with the oldest light?  Ancient light from the Big Bang, the start of the Universe,  has revealed a precise new estimate for the universe's age: 13.77 billion years, + or - 40 million years.  This new estimate is based on data from an array of telescopes in the Chilean Atacama Desert.   In addition to how old it is,  how fast is the universe expanding is another question? 

-  2785  -  MARS  -  Jezero Crator exploration?  -  On July 30, 2020 NASA launched its most sophisticated and ambitious spacecraft to Mars in the search for signs of life beyond Earth.   The spacecraft is aptly named “Perseverance Rover“. 

-  2786  -  BRAIN  -  how does it work?   How the brain works remains a puzzle with only a few pieces in place. Remember the brain is trying to figure out itself.  Of these, one big piece is actually a conjecture: that there’s a relationship between the physical structure of the brain and how it functions.  I’ve been thinking about that and here is what I have come up with.

-  2787  -  MARS  -  Curiosity for 8 years.  The NASA’s car-sized Curiosity rover celebrates eight (Earth) years on the Red Planet today (August 5, 2020), less than a week after its replacement the Perseverance rover took flight toward Mars. 

-  2788  -  LIFE  -  how rare in the Universe?  -  We learn about the history of the Universe just by looking at our own bodies. A fully grown adult human is an incredibly complex system, made up of trillions of cells and somewhere in the neighborhood of 1,028 atoms.  Atoms are the building blocks of all matter on Earth, and the Universe.

-  2789  -  TELESCOPES  -  to do a 3D map of the Universe.   Since 2005, scientists have been scanning the night sky to create a three-dimensional map of our universe with the purpose of shedding light on one of the biggest mysteries in physics.  The quest is to learn the true nature and identity of dark energy and dark matter. 

-  2790  -  DARK  MATTER  -  to discover what it is?  -  There is a race to discover “dark matter“. Dark matter is that elusive substance that has mystified science since the 1930s, when astronomers first realized galaxies needed some kind of invisible gravitational glue to hold them together. No one knew what it was, so it was named “dark matter“. 

-  2791  -  MOON  -  measuring the distance?  -  The distance to the Moon is 240,000 miles.  I learned that in High School.  Today the average distance is measured to be 238,856 miles.  Actually that distance can be measured to within less than an inch.

-  2792  -  SPACETIME  -  Theory of Relativity.  How it messed up geometry.    Our Universe isn’t made up merely of three space dimensions, but of four “spacetime” dimensions.  Three of them are space and one of them is time, and that’s where we get spacetime. The shortest distance between two spacetime events isn’t a straight line any longer. Why is that?

-  2794  -  ASTEROIDS  -  and planets visiting us?  Every 50,000 years or so, another star passes near our solar system. Most visitors brush by without incident. But, every once in a while, one comes so close that it gains a prominent place in Earth’s night sky, as well as knocks distant comets loose from their orbits.

DARK ENERGY - a mystery for science?

 -  2793  -  DARK  ENERGY  -  a mystery for science? Dark energy is one of the greatest mysteries in science today. We know very little about it, other than it is invisible, yet it fills the whole universe, and it pushes galaxies away from each other. The result of this force is that it is making our cosmos expand at an accelerated rate. 

--------------------------  2793  -  DARK  ENERGY  -  a mystery for science?

-  So, what is Dark Energy? One of the simplest explanations is that it is a “cosmological constant”.  So, what is the cosmological constant? It is a constant result of the energy of empty space expanding itself.  

-

-  Many physicists aren’t satisfied with Einstein’s equation as explanation by itself. They want a more fundamental description of dark energy’s nature. Is it some new type of energy field or exotic fluid? Or is it a sign that Einstein’s equations of gravity are somehow incomplete?  It is certain we don’t really understand the universe’s current rate of expansion.

-

-  This mysterious quantity known as dark energy makes up nearly three-fourths of the mass-energy of the universe, yet scientists are unsure not only what it is but how it operates. How, then, can they know this strange source exists?  Remember mass and energy are two forms of the same thing, E = mc^2.

-

-  In 1929, American astronomer Edwin Hubble studied exploding stars known as supernovae to determine that the universe is expanding. Since then, scientists have sought to determine just how fast it is expanding. It seemed obvious that gravity, the force which draws everything together, would put the brakes on the spreading cosmos eventually, so the question many asked was, just how much was the expansion slowing?

-

-  Far away galaxy clusters are representatives that were used to track the effects of dark energy on these massive objects over time. Most of the matter in galaxy clusters is in the form of very hot gas, which emits copious amounts of X-rays.

-

-  In the 1990s, two independent teams of astrophysicists again turned their eyes to distant supernovae to calculate the deceleration of the Universe. To their surprise, they found that the expansion of the universe wasn't slowing down, it was speeding up! Something must be counteracting gravity, something which the scientists dubbed "dark energy."

-

-  Calculating the energy needed to overcome gravity, scientists determined that dark energy makes up roughly 68 percent of the universe. “Dark matter” makes up another 27 percent, leaving the "normal" matter that we are familiar with to make up less than 5 percent of the cosmos around us.

-

-  Knowing how dark energy affects the spreading universe only tells scientists so much. The properties of the unknown quantity are still up for grabs. Recent observations have indicated that dark energy has behaved constantly over the universe's history, which provides some insight into the unseen material.

-

-  One possible solution for dark energy is that the universe is filled with a changing energy field, known as "quintessence." Another is that scientists do not correctly understand how gravity works.

-

-  Today’s leading theory considers dark energy a property of space. Albert Einstein was the first to understand that space was not simply empty. He also understood that more space could continue to come into existence.

-

-   In Einstein’s theory of general relativity, he included a “cosmological constant of expansion” to account for the stationary universe scientists thought existed. After Hubble announced the expanding universe, Einstein called his constant his "biggest blunder."  It was not stationary it was rapidly expanding.

-

-  But Einstein's blunder may be the best fit for dark energy. Predicting that empty space can have its own energy, the constant indicates that as more space emerges, more energy would be added to the universe, increasing its expansion.

-

-  Dark energy makes up most of the universe, but dark matter also covers a sizeable chunk. Comprising nearly 27 percent of the universe, and 80 percent of all the matter, dark matter also plays a dominant role.

-

-  Like dark energy, dark matter continues to confound scientists. While dark energy is a force that accounts for the expanding universe, dark matter explains how groups of objects function together.  It is what keeps rotating galaxies from flying apart.

-

-  In the 1950s, scientists studying other galaxies expected gravity to cause the centers to rotate faster than the outer edges, based on the distribution of the objects inside of them. To their surprise, both regions rotated at the same rate, indicating that the spiral galaxies contained significantly more mass than they appeared to. 

-

-  Studies of gas inside elliptical galaxies and of clusters of galaxies revealed that this hidden matter was spread throughout the universe.

-

-  Scientists have a number of potential candidates for dark matter, ranging to incredibly dim objects to strange particles. But whatever the source of both dark matter and dark energy, it is clear that the universe is affected by things that scientists can't conventionally observe.

-

-  A new telescope survey, the “Baryon Oscillation Spectroscopic Survey (eBOSS)” has come up with some answers. The survey is describing the largest three-dimensional cosmological map ever created.

-

-  Currently, the only way we can feel the presence of dark energy is with observations of the distant universe. The farther galaxies are, the younger they appear to us. That’s because the light they emit took millions or even billions of years to reach our telescopes. Thanks to this sort of time-machine, we can measure different distances in space at different cosmic times, helping us work out how quickly the universe is expanding.

-

-  Using the “Sloan Digital Sky Survey” telescope, more than two million galaxies and quasars have been measured.  Quasars are extremely bright and distant objects that are powered by black holes. This new map covers around 11 billion years of cosmic history that was essentially unexplored, teaching us about dark energy like never before.

-

-  Results show that about 69% of our universe’s energy is dark energy.  When combining the information from this map with other cosmological probes, such as the cosmic microwave background, these astronomers  prefer the cosmological constant over more exotic explanations of dark energy.

-

-  Combining the Sloan Survey observations with studies of the universe in its infancy reveals cracks in the description of its evolution. In particular, these measurement of the current rate of expansion of the universe is about 10% lower than the value found using direct methods of measuring distances to nearby galaxies. Both these methods claim their result is correct and very precise, so their difference cannot simply be a statistical fluke.

-

-  The precision of eBOSS enhances this crisis. There is no broadly accepted explanation for this discrepancy. It may be that someone made a subtle mistake in one of these studies. Or it may be a sign that we need new physics.

-

-   One exciting possibility is that a previously unknown form of matter from the early universe might have left a trace on our history. This is known as “early dark energy”, thought to be present when the universe was young, which could have modified the cosmic expansion rate.

-

-  Recent studies of the cosmic microwave background suggested that the geometry of space may be curved instead of being simply flat, which is consistent with the most accepted theory of the big bang. But this study concluded that space is indeed “flat‘.

-

-  Even after these important advances, cosmologists over the world will remain puzzled by the apparent simplicity of dark energy, the flatness of space and the controversial values of the expansion rate today. 

-

-  There is only one way forward in the quest for answers, making larger and more detailed maps of the universe. Several projects are aiming to measure at least ten times more galaxies than currently completed.

-

-  If the maps from eBOSS were the first to explore a previously missing gap of 11 billion years of our history, the new generation of telescopes will make a high-resolution version of the same period of time. 

-

-  It is exciting to think about the fact that future surveys may be able to resolve the remaining mysteries about the universe’s expansion in the next decade or so. But it would be equally exciting if they revealed more surprises.

-

-  See Review 2758  -  

-

-

-  See Review 2632  -   DARK  ENERGY  -  some form of anti-gravity?  - Is dark energy the “cosmological constant“. The fact that we see the Universe expanding as it does means that there must be some new form of energy causing these distant galaxies to recede from us faster and faster as time goes on.

-

-  This Review 2632 lists 20 more reviews about Dark Energy:

-

-  August 19, 2020                                                                             2793                                                                                                                                                

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 ---------------------   Thursday, August 20, 2020  -------------------------

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SPACETIME - now you can explain it?

 -  2792  -  SPACETIME  -  Theory of Relativity.  How it messed up geometry.    Our Universe isn’t made up merely of three space dimensions, but of four “spacetime” dimensions.  Three of them are space and one of them is time, and that’s where we get spacetime. The shortest distance between two spacetime events isn’t a straight line any longer. Why is that?

--------------------------  2792  -   SPACETIME  -  now you can explain it?

-  “What’s the shortest distance between two points?”   Most of us will give the same answer that Archimedes gave more than 2,000 years ago: a straight line. If you take a flat sheet of paper and put two points down on it absolutely anywhere, you can connect those two points with any line, curve, or geometrical path you can imagine. So long as the paper remains flat, uncurved, and unbent in any way, the straight line connecting those two points will be the shortest way to connect them.

-

-  This is precisely how the three dimensions of space work in our Universe: in flat space, the shortest distance between any two points is a straight line. This is true regardless of how you rotate, orient, or otherwise position those two points. 

-

-  The distance between two points depends on the path taken; displacement does not.

Normally, we measure the distance between two points by the distance traveled.  

-

-  A straight line being the shortest distance between two points comes from the Pythagorean theorem. The Pythagorean theorem as a rule about right triangles, that if you square each of the short sides and add them together, that equals the square of the long side.

-

-   If the short sides are a and b while the long side is c, then the equation relating them is:

-

----------------------------------   a² + b² = c².

-

-  Think about what this means, however, not from the perspective of pure mathematics alone, but in terms of distances. It means that if you move through one of your spatial dimensions by a certain amount (a, for example) and then move through a perpendicular dimension by another amount (b, for instance), then the distance between where you began and where you wound up is equal to c, as defined by the Pythagorean theorem. 

-

-  The distance between any two points on a plane, where those points are separated by a in one dimension and b in another dimension, is c, where:

-

---------------------------------   c = √(a² + b²).

-

-  In our Universe, we’re not restricted to living on a flat plain. We have not just length and width (or the x and y directions,) dimensions to our Universe, but depth (or the z direction) as well. 

-

-  If you want to figure out what the distance is between any two points in space, it’s the exact same method as it was in two dimensions, except with one extra dimension thrown in. Whatever amount your two points are separated by in the x direction, the y direction, and the z direction, you can figure out the total distance between them in just the same way.

-

-  Because of the extra dimension, the distance between them is going to be given by:

-

------------------------   d = √(x² + y² + z²). 

-

-  This equation says that the distance between any two points is defined by the straight line connecting them: the line that accounts for the separation between your two points in all three dimensions: the x-direction, the y-direction, and the z-direction combined.

-

-  One of the interesting and important realizations about this relationship — the distance between two points being a straight line — is that it absolutely does not matter how you orient your visualization of the x, y, and z dimensions. You can either:

-

----------------------------  change your coordinates so that the x, y, and z dimensions are in any (mutually perpendicular) directions you like, or

-

---------------------------  rotate these two points by any amount in any direction,

and the distance between them will not change at all.

-

-  The individual components will change if you either rotate your perspective or rotate the line connecting those two points, as your definitions of length, width, and depth will change relative to one another for that line as the rotation occurs. But the overall distance between those two points doesn’t change at all; that quantity of the distance between those points remains what we call “invariant,” or unchanging, regardless of how you rotate them.

-

-  The distance between two objects doesn't depend on how your coordinates are oriented.  If time is just another  dimension, then the distance between any two points in spacetime will work the same way.

-

-   If we represent the time dimension as “t‘, you think the distance would be the straight line connecting two points through the three spatial dimensions as well as the time dimension. In mathematical terms, you might think that the equation for the separation between any two points would look something like:

-

------------------------------------   d = √(x² + y² + z² + t²).

-

-  This is much the same change we made when we went from two dimensions to three dimensions, except this time we’re going from three dimensions to four dimensions. It’s a reasonable step to attempt, and describes exactly what reality would look like if we had four dimensions of space, rather than three.

-

-  But we don’t have four dimensions of space; we have three dimensions of space and one dimension of time. And despite what your intuition may have told you, time isn’t “just another dimension.”

-

-  There are two ways that time, as a dimension, is different from space. The first way is a small one: you can’t put space (which is a measurement of distance) and time (which is a measurement of time) on the same footing without some way to convert one to the other.

-

-  Fortunately, one of the great revelations of Einstein’s theory of relativity was that there is an important, fundamental connection between distance and time: the speed of light, or equivalently, of any particle that travels through the Universe without a rest mass.

-

-  The speed of light in a vacuum, 299,792,458 meters per second, tells us precisely how to relate our motion through space with our motion through time. 

-

-  When we use terms like “one light-year” or “one light-second,” we’re talking about distances in terms of time: the amount of distance that light travels in one year (or one second).

-

-   If we want to convert “time” into a distance, we need to multiply it by the speed of light in a vacuum.

-

-  The key idea is that we’re all moving through the Universe, through both space and time, simultaneously. If we’re simply sitting here, stationary, and not moving through space at all, then we move through time at a very specific rate at which we’re all familiar: one second per second.

-

-  However, the faster you move through space, the slower you move through time. The other dimensions are not like this at all: your motion through the x dimension in space is completely independent of your motion through the y and z dimensions. But your total motion through space, relative to any other observer, determines your motion through time. The more you move through one (space or time), the less you move through the other.

-

-  Einstein’s relativity gives us concepts like time dilation and length contraction. If you move at very low speeds compared to the speed of light, you won’t notice these effects: time appears to move at one second per second for everyone, and lengths appear to be the same distance for everyone at speeds normally achievable on Earth.

-

-  But as you approach the speed of light, or rather, as you perceive an object where the relative speed between you and it is close to the speed of light, you’ll observe that it’s contracted along its direction of relative motion, and that clocks appear to run at a slower (dilated) rate relative to your own clocks.

-

-  The reason underlying this is because the speed of light is the same for all observers. If you imagine that a clock is defined by light bouncing back and forth between two mirrors, then watching someone else’s clock as they move close to the speed of light will inevitably result in their clock running slower than your own because it takes time for the light to reach you.

-

-  There is an even deeper insight here, which initially eluded even Einstein himself. If you treat time as a dimension, multiply it by the speed of light, and treat it as though it were imaginary, rather than real, then we can define a “spacetime interval” the same way we defined distance earlier. Only, since the imaginary number “i” is just √(-1), this means that the spacetime interval is actually;

-

---------------------------  d = √(x² + y² + z² - c²t²).

-

-   Note the minus sign attached to the time coordinate!

-

-  In other words, the transformation from “motion through or separation in space” to “motion through or separation in time” is also a rotation, but it’s a rotation not in the cartesian coordinates of space (where x, y, and z are all real numbers), but through the “hyperbolic coordinates of spacetime“, where if the space coordinates are real, then the time coordinate must be imaginary.   Read that again!

-  

-  What’s remarkable about all of this is that Einstein, despite lacking the mathematical insight to understand exactly how the dimension of time was related to the three conventional dimensions of space, was still able to piece together this key physical insight. 

-

-  Increasing your motion through space decreased your motion through time, and increasing your motion through time decreased your motion through space. All measurements of space and time are only meaningful relative to the observer in question, and depend on the relative motion of the observer to the observed.

-

-  Yet, the spacetime interval remains invariant. No matter who is doing the observing or how quickly they’re moving, the combined motion of any object through “spacetime” is something all observers can agree on.

-

-   Fortunately, in physics, the Universe itself, not anyone’s theory, is the ultimate arbiter of scientific truth.

-

-------------------------------  Other Reviews about spacetime:

-

-  2722  -  SPACETIME  -  at the macro and micro levels.?   How Can Space and Time be Related?.   Space and time seem to be absolute quantities to us.  It is hard to see their interrelationship until you take their ratio as velocity and extend that ratio to its limits.  Velocity is space / time!

-

- 2707  -  SPACETIME  -  still a conundrum in science?   Our universe that we know today is extremely unnatural.  It is a weird permutation among countless other possibilities, observed for no other reason than that its special conditions allowed life to arise.  The properties of the universe are inevitable, predictable, ‘natural,’ locking together into a sensible pattern.  It is our challenge to make sense of it.

-

-  2699 -  SPACETIME  -  Einstein and the expanding Universe ?   At what speed is the universe expanding? Until now, at least two independent calculation methods have arrived at two values that are different by about 10% with a deviation that is statistically irreconcilable.

- 

-  2567  -  SPACETIME  -  creating new physics?  Einstein invented spacetime to explain gravity.  Gravity is bent spacetime.  All objects, (ie:mass), move through gravity seeking the shortest distance and shortest time through the bent spacetime created by the mass.  Before Einstein almost everybody thought Isaac Newton already had figured it all out. 

-

-  2523  -  SPACETIME  -  Fast Speed and Short Time.  You should be fascinated by time and space.  Both seem so fundamental, yet, Einstein’s Theory of relativity proves that time and space are not absolutes.  They are relative.  They are one thing, not two things, spacetime is one thing.  Space and Time bend and curve when they interact with mass.  Mass tells spacetime how to bend and spacetime tells mass how to move.

-

-  2522  -  Space - curved or flat?  Also, lists 14 more reviews about space.

-

-  2271  -  Hw can space and time be related?  Also lists 13 more reviews about spacetime.   Space and time seem to be absolute quantities to us.  It is hard to see their interrelationship until you take their ratio as velocity and extend that ratio to its limits.  In order for the speed of light to be a constant physical law in the Universe, regardless of the relative motion of all observers everywhere, then space and time must change in a compensating way to keep the velocity constant.

-

-  2213  -  Spacetime from atoms to blackholes.

-  2180  -  Velocity is space divide by time.

-  2074  -  Much todo about nothing,  ie space.

-  1790  -  Space bends and time slows.

-  1242  -  How does spacetime change at the micro level?

-  1189  -  The beginning of time?

-  1006 -  Is time slowing down?

-  910  -  Time to think?

-  854  -  Time , GPS, and Entropy?

-  842   -  Pressed for time?

-  830  -  Why a 24 hour day?

-  814  -  Fast speed and short time?

-  783, 784 -  Time is what God crested to keep everything from happening all at once.

-  747 -  Why 60 minutes?

-  590  -  So you want to go into space?

-  392  -  Time dilation derived using the Pythagorean Theorem

-  354  -  The big picture using a universal calendar.

-

-  August 18, 2020                                                                             2792                                                                                                                                                 

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 ---------------------   Wednesday, August 19, 2020  -------------------------

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MOON - measuring the distance?

 -  2791  -  MOON  -  measuring the distance?  -  The distance to the Moon is 240,000 miles.  I learned that in High School.  Today the average distance is measured to be 238,856 miles.  Actually that distance can be measured to within less than an inch.

-

--------------------------  2791  - MOON  -  measuring the distance?         

-

-  Lasers can measure the distance between surfaces of Earth and the Moon using laser ranging. Lasers at observatories on Earth are aimed at retroreflectors planted on the Moon during the Apollo program .

-

-   Laser light pulses are transmitted and reflected back to Earth, and the round-trip duration is measured. The lunar distance is calculated from this value.

-

-  The first successful tests were carried out in 1962 by observing laser pulses reflected from the Moon's surface using a laser with a millisecond pulse length. 

-

-   Greater accuracy was achieved following the installation of a retroreflector array on July 21, 1969, by the crew of Apollo 11, and two more retroreflector arrays left by the Apollo 14 and Apollo 15 missions have also contributed to the experiment. Successful lunar laser range measurements to the retroreflectors were first reported by the 3.1 m telescope at Lick Observatory

-

-  The Apollo 15 array is three times the size of the arrays left by the two earlier Apollo missions. Its size made it the target of three-quarters of the sample measurements taken in the first 25 years of the experiment. 

-

-  The distance to the Moon is calculated approximately using the equation: 

-

--------------------  distance = (speed of light × duration of delay due to reflection) / 2

-

--------------------  233,000 miles  =  186,000 miles / second  *  1.25 seconds

-

-------------------   Actually 238,856 miles using more precise data.

-

-  To compute the lunar distance more precisely, many factors must be considered in addition to the round-trip time of about 2.5 seconds. These factors include the location of the Moon in the sky, the relative motion of Earth and the Moon, Earth's rotation, lunar libration, polar motion, weather, speed of light in various parts of air, propagation delay through Earth's atmosphere, the location of the observing station and its motion due to crustal motion and tides, and relativistic effects.

-

-  The distance continually changes for a number of reasons, but averages 239,228.3 miles between the center of the Earth and the center of the Moon during its monthly orbits.

-

-  At the Moon's surface, the laser beam is about 4.0 miles wide and scientists liken the task of aiming the beam to using a rifle to hit a moving dime 1.9 miles away. 

-

-  The reflected light is too weak to see with the human eye. Out of 1,017 photons aimed at the reflector, only one is received back on Earth, even under good conditions. They can be identified as originating from the laser because the laser is highly monochromatic.

-  This is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to within 0.01 inches. 

-

-  The upcoming MoonLIGHT reflector, that may be placed during an attempt by the private MX-1E lander, is designed to increase measurement accuracy 100 times over existing systems. MX-1E was set for launch in July 2020, however,  as of August 2020, the launch of the MX-1E has been canceled.

-

-  The Moon is spiraling away from Earth at a rate of 3.8 cm/year.

-

-  The Moon probably has a liquid core of about 20% of the Moon's radius. The radius of the lunar core-mantle boundary is determined as 381±12 km.

-  

-  Einstein's theory of gravity and the general theory of relativity predict the Moon's orbit to within the accuracy of these laser ranging measurements.

- 

- During their historic moonwalk on July 20, 1969, Armstrong and Aldrin deployed the first laser retroreflector on the surface of Tranquility Base.

-

-  The 46-centimeter (18-inch) square array contained 100 corner cube prism reflectors, special mirrors that send any light striking them straight back to its source. Less than two weeks later, on Aug. 1, 1969, a laser pulse aimed through the lens of the 3-meter telescope at California’s Lick Observatory successfully hit the array for the first time.

-

-  With today’s more sophisticated laser ranging systems, the precision of the Earth-Moon distance measurement is now approximately 1 millimeter (0.04 inch), 25 times better than the first calculations in 1969. 

-

-  By comparison, that’s approximately equivalent to determining the distance between New York and Los Angeles to 0.01 millimeters (0.0004 inch). 

-

-  Along with the Earth-Moon distance measurement, the devices have revealed that the moon is moving away from the Earth at a rate of 3.8 centimeters (1.5 inches) per year, our satellite probably has a liquid core, and the universal force of gravity is very stable with measurements showing that Newton’s gravitational constant has changed less than 1 part in 100 billion since the laser experiments began.

-

-  Hitting one of the retroreflectors with a laser beam from Earth has been compared to using a rifle to hit a moving dime 3 kilometers (1.9 miles) away.  Quite a good shot wouldn’t you say!

-

-  August 17, 2020                                                                             2791                                                                                                                                                 

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-----  Comments appreciated and Pass it on to whomever is interested. ---- 

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--  email feedback, corrections, request for copies or Index of all reviews 

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 ---------------------   Tuesday, August 18, 2020  -------------------------

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