The Universe in the Past
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First Hundred Thousand Years of Our Universe

First Hundred Thousand Years of Our Universe | The Universe in the Past | Scoop.it

 A new analysis of cosmic microwave background (CMB) radiation data by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) has taken the furthest look back through time yet – 100 years to 300,000 years after the Big Bang – and provided tantalizing new hints of clues as to what might have happened.


Via Michele Diodati
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donna dedic's comment, August 27, 2013 7:42 AM
This article talks about how the best way to find out answers and solve mysteries and that way is to go backwards. They believe revisiting the scene and look for evidence or any sorts of clues will help them find the answer. Scientists are trying to go back as much as they can to the Big Bang to research more about it.
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How far backwards in time is it possible to see?

How far backwards in time is it possible to see? | The Universe in the Past | Scoop.it

"The furthest back in time that we are currently actively seeing is

 

13,7 _ 0,15 billion years -- 379,000 years

 

The 13.7 billion years is the currently measured time to the Big Bang and 379,000 years is the number of years after the Big Bang when the universe cooled off enough to become transparent. The (mostly visible light) photons from the hot plasma that filled the universe at that time have been traveling since then and have now been red-shifted down into the microwave range. This is the Cosmic Microwave Background radiation that has been very accurately measured by the WMAP satellite.

 

We will not be able to see back further in time (to before 379,000 years after the Big Bang) with photons since the universe was opaque to photons before that time.

 

However, if we are ever able to use neutrino telescopes to measure very low energy neutrinos (which is probably impossible), then we would be able to see back to a few minutes after the Big Bang. Finally, it is also theoretically possible to see back to roughly seconds after the Big Bang if we could measure the possible gravitational waves that could have been generated at the end of the inflationary period of the Big Bang at that time."

 

See also:

 

If there was a mirror a million light years away and I looked at via telescope, how far back would I see in the past?


http://www.quora.com/If-there-was-a-mirror-a-million-light-years-away-and-I-looked-at-via-telescope-how-far-back-would-I-see-in-the-past


Via Amira, Dr. Stefan Gruenwald
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Universe may not be expanding after all but may be gaining mass instead -- initial singularity no longer needed

Universe may not be expanding after all but may be gaining mass instead -- initial singularity no longer needed | The Universe in the Past | Scoop.it
Particles' changing masses could explain why distant galaxies appear to be rushing away.

 

The Universe started in a big bang and has been expanding ever since. For nearly a century, this has been the standard view of the Universe. Now one cosmologist is proposing a radically different interpretation of events — in which the Universe is not expanding at all.

 

In a paper posted on the arXiv preprint server, Christof Wetterich, a theoretical physicist at the University of Heidelberg in Germany, has devised a different cosmology scenario in which the Universe is not expanding but the mass of everything has been increasing. Such an interpretation could help physicists to understand problematic issues such as the so-called singularity present at the Big Bang, he says.

 

Astronomers measure whether objects are moving away from or towards Earth by analysing the light that their atoms emit or absorb, which comes in characteristic colours, or frequencies. When matter is moving away from us, these frequencies appear shifted towards the red, or lower-frequency, part of the spectrum, in the same way that we hear the pitch of an ambulance siren drop as it speeds past. In the 1920s, astronomers including Georges Lemaître and Edwin Hubble found that most galaxies exhibit such a redshift — and that the redshift was greater for more distant galaxies. From these observations, they deduced that the Universe must be expanding.

 

But, as Wetterich points out, the characteristic light emitted by atoms is also governed by the masses of the atoms' elementary particles, and in particular of their electrons. If an atom were to grow in mass, the photons it emits would become more energetic. Because higher energies correspond to higher frequencies, the emission and absorption frequencies would move towards the blue part of the spectrum. Conversely, if the particles were to become lighter, the frequencies would become redshifted.

 

Because the speed of light is finite, when we look at distant galaxies we are looking backwards in time — seeing them as they would have been when they emitted the light that we observe. If all masses were once lower, and had been constantly increasing, the colours of old galaxies would look redshifted in comparison to current frequencies, and the amount of redshift would be proportionate to their distances from Earth. Thus, the redshift would make galaxies seem to be receding even if they were not.

 

Work through the maths in this alternative interpretation of redshift, and all of cosmology looks very different. The Universe still expands rapidly during a short-lived period known as inflation. But prior to inflation, according to Wetterich, the Big Bang no longer contains a 'singularity' where the density of the Universe would be infinite. Instead, the Big Bang stretches out in the past over an essentially infinite period of time. And the current cosmos could be static, or even beginning to contract.

 

The idea may be plausible, but it comes with a big problem: it can't be tested. Mass is what’s known as a dimensional quantity, and can be measured only relative to something else. For instance, every mass on Earth is ultimately determined relative to a kilogram standard that sits in a vault on the outskirts of Paris, at the International Bureau of Weights and Measures. If the mass of everything — including the official kilogramme — has been growing proportionally over time, there could be no way to find out.

 

For Wetterich, the lack of an experimental test misses the point. He says that his interpretation could be useful for thinking about different cosmological models, in the same way that physicists use different interpretations of quantum mechanics that are all mathematically consistent. In particular, Wetterich says, the lack of a Big Bang singularity is a major advantage.

 

He will have a hard time winning everyone over to his interpretation. “I remain to be convinced about the advantage, or novelty, of this picture,” says Niayesh Afshordi, an astrophysicist at the Perimeter Institute in Waterloo, Canada. According to Afshordi, cosmologists envisage the Universe as expanding only because it is the most convenient interpretation of galaxies' redshift.

 

Others say that Wetterich’s interpretation could help to keep cosmologists from becoming entrenched in one way of thinking. “The field of cosmology these days is converging on a standard model, centred around inflation and the Big Bang,” says physicist Arjun Berera at the University of Edinburgh, UK. “This is why it’s as important as ever, before we get too comfortable, to see if there are alternative explanations consistent with all known observation.”

 


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Peter Phillips's curator insight, July 25, 2013 3:06 PM

Wetterich points out, the characteristic light emitted by atoms is also governed by the masses of the atoms' elementary particles, and in particular of their electrons. If an atom were to grow in mass, the photons it emits would become more energetic. Because higher energies correspond to higher frequencies, the emission and absorption frequencies would move towards the blue part of the spectrum. Conversely, if the particles were to become lighter, the frequencies would become redshifted.

 

Because the speed of light is finite, when we look at distant galaxies we are looking backwards in time — seeing them as they would have been when they emitted the light that we observe. If all masses were once lower, and had been constantly increasing, the colours of old galaxies would look redshifted in comparison to current frequencies, and the amount of redshift would be proportionate to their distances from Earth. Thus, the redshift would make galaxies seem to be receding even if they were not.

Marie Rippen's curator insight, July 26, 2013 4:53 PM

Thought-provoking stuff, but the last point is my favorite--the idea that this theory is important mostly because it upends current assumptions. So much of what we think we know about the world is based upon unproven theories that we must keep an open mind even when our cherished dogma is threatened.

Science is so much more about what we don't know than what we do.