Mission Control Live: NASA InSight Mars Landing Live Coverage

[Eli]

"NASA's Mars Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) lander is scheduled to touch down on the Red Planet at approximately 3 p.m. EST Nov. 26. ....

This Mars InSight Mission was launched on May 5, 2018, and after the journey of 6.5 months, the NASA's InSight mission finally reached to the Mars planet. This Mars Insight mission will land on the Mars planet in the next few hours." Watch Live now:

[Joseph Bundala]

I see, so this mission will eventually figure out if the planet is safe for humans, right? I saw earth-is-flat guys bombarding NASA's page with negative comments about this mission.

Anyway, does it mean the source of life is just water? Hope they won't bring back crazy diseases, bacteria to earth.

Watch this movie: LIFE: "We are looking at the first proof of LIFE beyond Earth"

[Eli]

The source of life is very complicated, a possibility for existence of other planets where life can exist is a growing area of interest in research, often boosted by space missions such as NASA, see for examples:

nasa-has-found-another-20-promising-pla ... onize-5591

live-streaming-spacex-falcon-heavy-rock ... orida-5696

The crazy mission is the one, in which people are competitively eager to go and live in Mars, where a possibility of death is almost certain: 100 finalists have been chosen for a one-way trip to Mars

[Eli]

@Simulink The earth (The earth is a very small dot, negligible when considering large-scale structures of the universe) is not flat as the "earth-is-flat" guy claims, but the universe is approximately flat in sufficiently very large scales. Interestingly, there are currently 3 universe model geometries: flat, elliptic and hyperbolic. These universe's shapes are determined by the density parameter of the universe, \(\Omega\) which is the average density of the universe divided by the critical energy density. Critical density is the mass-energy required to create a flat universe.

According to the theory of general relativity, mass and energy bend the curvature of spacetime and this is used to determine what curvature the universe has by using the value of density parameter:

If \(\Omega =1\), the universe is flat
If \(\Omega >1\), there is positive curvature (elliptic universe)
if \(\Omega < 1\) there is negative curvature (hyperbolic universe)



See more: Shape of the Universe

Everything is just "Big Banged":

[Joseph Bundala]

Thank you @Eli for clarification. The universe thing and our origin is confusing sometimes. I have these questions and anyone may answer them, just curious:

1. Does the universe expand? Is it like a bubble which may explode at it's limit?
2. If you place identical twins at different gravitational pull, say one near the horizon and other on earth. Will they age same in respect of relativity theorem?
3. I read that gravitational force on Mars is 38% that of earth. If you weigh 100 kg on earth then you will have 38 kg on mars, right? I am curious to know if humans will feel this deference there. This question can also refer qn 2 above.

[Eli]

1. The universe expands, and its expansion is so rapid. More recent discovery has shown that the expansion of the universe is accelerating. This evolutionary infinite expansion of the universe is propelled by what is called dark energy. In 1929, Edwin Hubble examined and revealed that the wavelength of light photon emitted by distant galaxies was red-shifted towards the red end of the electromagnetic spectrum as the photon traveled through space. Hubble found that, fainter more distant galaxies showed a large degree of redshift than closer galaxies. The redshift occurs because the wavelengths of light are stretched as the universe expands. Dark energy, \(\Lambda\), is the most abundant "stuff" in the universe budget.



2. Your second question relates to what is called "Twins Paradox": (reference - https://en.wikipedia.org/wiki/Twin_paradox)

"In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, according to an incorrect and naive application of time dilation and the principle of relativity, each should paradoxically find the other to have aged less. However, this scenario can be resolved within the standard framework of special relativity: the traveling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey, and so there is no symmetry between the spacetime paths of the twins. Therefore, the twin paradox is not a paradox in the sense of a logical contradiction. "

Spacetime is a mathematical approach that treats the three dimensions of space and the one dimension of time into a single four-dimensional continuum.

The concepts of Twins Paradox and Spacetime are brilliantly explained in this video:



3. "Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied. The object's mass also determines the strength of its gravitational attraction to other bodies.

Mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force." - reference: https://en.wikipedia.org/wiki/Mass

But, here are two different school of thoughts regarding gravity, Newtonian gravity vs Einstein's general/special relativity

Newton's law of universal gravitation states that every mass attracts every other mass in the universe, and the gravitational force between two bodies is proportional to the product of their masses, and inversely proportional to the squared distance between them. Newton further asserted that the force of gravity is always attractive, works instantaneously at a distance (it involves instantaneous action at a distance, i.e., Newton's laws assume that gravity is an innate force of an object that can act over a distance), and has an infinite range. Most importantly, it affects everything with mass - and has nothing to do with an object's charge or chemical composition. Therefore, spherical objects like planets and stars act as if all of their mass is concentrated at their center, and so the distance between objects should include the distance to the center of both objects.

On the other hand,

Einstein published his theory of general relativity in 1915. In it, he determined that massive objects cause a distortion in space-time, which is felt as gravity: " Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels (Equivalence Principle). As a result, he found that space and time were interwoven into a single continuum known as space-time. Events that occur at the same time for one observer could occur at different times for another. In the world of Newtonian physics, everything looks the same to everyone else in the universe, irrespective of their location and speed.

One should think of "spacetime as an elastic sheet that bends or deforms or gets disturbed under the weight of objects placed upon it. The more massive the object, the more spacetime bends. This bending or deformation or disturbance is called gravity." Objects with more mass bend the sheet more and this pushes other objects in the bend towards themselves. This makes gravity look more like a push rather than a pull.
According to Einstein's theory of GR the force of gravity is not always attractive, and it doesn't work instantaneously at a distance, and doesn't have infinite range. Einstein therefore came up with a more unified and all-inclusive explanation of gravity, making it able to explain scenarios even in such phenomena as particles and waves, by regarding gravity as a distortion in the curvature of fabric of spacetime.

Newton's law of gravity is limited to non-relativistic speeds and low gravitational fields, and within those limits it is very accurate. General relativity expanded the range of physical conditions over which it applies. Special relativity extended the range to include high speeds, and general relativity extended it again to include high gravitational fields. Even general relativity is not applicable everywhere because it fails at singularities like the center of black holes. General relativity is however consistent with special relativity, and reduces to Newtonian gravity in the appropriate limits.

See more:

Newtonian gravity vs. general relativity: exactly how wrong is Newton?

What is wrong with Newtonian gravity? Why is general relativity better?

Quantum gravity?

Is it possible that quantum gravity and general relativity are not compatible because relativity is wrong and quantum gravity is right?

[Eli]

https://www.space.com/40958-einstein-ge ... alaxy.html

[Eli]

GR may not be the only theory that explains the evolution of the Universe, although it has been tested with high precision to work on small scales.

Paper:

https://arxiv.org/abs/1907.02977

Featured paper news:

https://www.sciencedaily.com/releases/2 ... 131153.htm

[Eli]

f(R) gravity theories:

https://arxiv.org/abs/0805.1726

[Eli]

How many planets and planetary systems are there?

http://exoplanet.eu/catalog.php