[Death of the universe?](6)

Death of the universe?(6)
Hubble sees more than just stars and galaxies.It just might be on to one of the key ingredient of space.An invisible ingredient that could put the brakes on dark energy's effect and cause a Big Chill.That's dark matter.Scientists talk about dark matter as the substance that holds the universe together and could prevent a Big Rip.Evidence that dark matter exists is seen in some of Hubble's images of nearby galaxies.It sometimes appears as though other galaxies surround them.The other galaxies are not really there at all.Rather they are reflections of more distant galaxies coming from behind.

Astronomers suspect this optical illusion is dark matter causing aweird distortion of light called gravitational lensing.The light from the more distant galaxies is literally bent by the curvature of space caused by stars and dark matter in its path.The more dark matter there is between Earth and the distant galaxy the more the light will be bent and the greater the force to cause a Big Chill.

The gravitational lensing is a tremendous tool for the astronomer because we can measure the distortion in background galaxies and use it to trace the distribution of dark matter on various scales.We're looking at a you're wearing them.And you can tell how much that bending is occurring, you can map the dark matter and you can also see well if there's dark matter there is the universe around that dark matter behaving the way it should given the gravity or not?

Identifying which energy force dominates dark matter or dark energy will give scientists more confidence about whether a Big Chill or Big Rip will be our fate.The best evidence shows dark energy as the driving force.But by how much?Solving this mystery depends on astronomers finding ways to measure how fast the universe is moving.On Earth it's simple to determine how fast something moves.An airplane for example is relatively close.We can look at it and calculate its speed by estimating the distance it travels and timing how long it takes to get from one point to another.But the star's light can travel for millions or billions of years before it can be seen on earth.By the time its light gets here, the star will be long gone.And it's too far away to gauge its speed or distance traveled with any certainty.

The universe is expanding.Only scientists cannot give precise answers about how fast.The mystery moves closer to being solved by imaging the cosmos with greater precision.You couldn't even observe the galaxies that are in this image before Hubble Space Telescope was launched.So the increase in our capability with technology recently has been astounding.It has enabled us to do things to chart the evolution of the universe in a way that we never could have imagined.

Clearer images from space make it easier to estimate the rate of expansion.If the universe continues to expand with time, then  ultimately all of the energy sources. the nuclear furnaces and stars would run out and die and the universe would actually get very cold.And there would be somthing called the Big Chill.

In the Big Chill Scenario.Earth could become a lonely cold planet as the universe expands.Distances between stars grow so vast that they nearly disappear from view.Over time they burn out.And eventually  the entire universe ends in a frozen state.These are ideas that sprang from the work of Einstein and Hubble.Only neither of them lived long enough to see these results.

Imagine what Edwind Hubble and Albert Einstein would think if they were alive today watching the progress in th subject.You know Einstein thinking about the expanding universe as a natural solution to his equations but puzzles that the universe didn't appear to be changing.Edwind Hubble desperate to measure whether the universe was slowing down in its expansion.In fact they were both wrong.It's speeding up.

The time that Einstein developed the general theory we didn't know that there were other galaxies outside of our own Milky Way galaxy.And we didn't know that the universe was expanding.And in fact Einstein himself, despite the fact that his equations were screaming at him that the universe had to be evolving, didn't have enough confidence in that result to say the universe must be expanding or the universe must be contracting.

Still his work led to the scientific breakthroughs that would identify dark matter and dark energy. the forces that could cause a Big Chil.This sphere demonstrates the principles behind a Big Chill.The mables coming out of this sphere are like stars that were formed following the Big Bang.Dark energy propels the stars outward.Dark matter slows them down.In a Big Chill the expansion would continue but the nuclear fuel that cause the stars to burn will eventually run out.From Earth's perspective the  first thing to go would be sunlight.The sun dims as it exhausts its last bits of nuclear fuel.

Earth would freeze and become lifeless and billions of years after humans are gone, the cosmos expands out of view.A few newer stars might remain but most would have long moved away.The furnace powering the universe burns out.The darkened universe continues to expand.A frozen and lifeless remnant of its once vibrant existence.

Eventually if this keeps going if nothing changes in the composition of this energy density, the universe will continue to expand forever.It's going to get colder and colder and eventually even the gala our neighboring galaxies will be receding from us so fast that they won't be able to see them.So the universe is going to get cold and dark and it will be a very lonely place.

Death of the universe?(1)
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Death of the universe?(7 end)