Cosmologists find way to verify if the universe is hotter at one end than the other

March 7, 2018 by Darrin S. Joy, University of Southern California
A remnant of the Big Bang, the cosmic microwave background appears to harbor a gradient across the universe, a feature that has puzzled cosmologists for decades. Credit: Matthew Savino

Scientists have long observed an apparent gradient in the cosmic microwave background but have been unable to determine how much is real and how much is perceived. USC Dornsife researchers appear to have found a way to an answer.

Observed from Earth, the universe appears a bit hotter at one end than the other, at least in terms of the (CMB). But the question plaguing cosmologists is whether that imbalance in the CMB is real or a result of the Doppler effect.

USC Dornsife scientists Siavash Yasini and Elena Pierpaoli may have found a way to nail down an answer.

Made most famous perhaps by Edwin Hubble, who used it to show that the universe is expanding, the Doppler effect is the apparent shift in the frequency of electromagnetic waves due to the motion of bodies traveling swiftly through space. Waves such as electromagnetic radiation—light waves, X-rays, microwaves, etc.—appear to shift in energy, with those moving toward an observer appearing to be higher in energy, or hotter, than they really are. The opposite is true for waves moving away from the observer, which appear colder.

Scientists looking at the sky see space trailing behind Earth appearing colder than space up ahead, but it's not clear if that's only the Doppler effect or an observation of a true difference in CMB temperature. It's a puzzle that has persisted for decades.

Because the CMB is leftover energy from the Big Bang—when the entire universe exploded outward from a single point—cosmologists have assumed it is dispersed evenly. The appearance of two poles in the universe, one warmer than the other, must therefore be a result of the Doppler effect, a result of the solar system careening through space.

"We think that one side of the CMB only looks hotter because we are moving towards it, and the opposite side looks colder because we are moving away from it," said Yasini, a Ph.D. student in physics and astronomy.

Astrophysicists measuring the solar system's velocity relative to the CMB adjust their calculations based on this assumption, as do cosmologists studying the Big Bang and conditions shortly after.

But this might be a mistake after all.

"If there is an intrinsic dipole in the CMB—that is, if one side of the sky is actually partially hotter than the opposite side—the velocity we assign the solar system with respect to the CMB would be incorrect," Yasini said. This would affect how scientists measure the speed of distant objects such as galaxies, and theories about what happened moments after the Big Bang could be shaken.

Running calculations for a different but related study, Yasini and Professor of Physics and Astronomy Pierpaoli, who is Yasini's graduate school mentor, found an interesting detail: The frequency spectrum of the CMB averaged across the sky will differ if the dipole is real and not just a result of the Doppler effect.

In other words, if the CMB is, in fact, hotter at one end of the universe than the other, the average temperature measured across the whole sky will be slightly different than if the CMB is actually uniform.

Yasini and Pierpaoli's findings will allow cosmologists undertaking the next generation of CMB surveys to determine the nature of the CMB dipole for the first time ever, solving the puzzle.

"Now that we have a mathematical basis for finding an answer, it just remains to make the observations," Pierpaoli said.

If it turns out a portion of the dipole is real and not just a result of the Doppler , astrophysicists and astronomers will have to recalibrate all of their measurements to get a more accurate view of the observable universe.

Just as important, cosmologists studying the Big Bang and conditions in the very early universe will have new directions to explore to understand how and why the CMB is dispersed unevenly, and how the came to be as it now is.

Explore further: What is the cosmic microwave background radiation?

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RobertKarlStonjek
5 / 5 (3) Mar 07, 2018
Made most famous perhaps by Edwin Hubble, who used it to show that the universe is expanding...


This is inaccurate. Hubble was a sceptic on expansion and believed that there must be some other reason for the redshift. He reluctantly accepted the case argued by his colleagues, such as Tolmann, that the redshift was caused by 'radial velocity' only in his 1929 paper.

In his 1947 article 'The Problem of the Expanding Universe' he outlines his objections, to quote:
"The alternative interpretation of red shifts as velocity shifts leads to a particular type of an expanding universe which is disconcertingly young, small and dense. Moreover, the strange features of this universe are merely the dimming effects of recession expressed in other terms. Under these circumstances, the inclusion of the dimming factors seems to be a questionable procedure. In other words, the empirical evidence now available does not favor the interpretation of red shifts as velocity shifts."
RobertKarlStonjek
5 / 5 (2) Mar 07, 2018
...and in a 1935 paper 'Two Methods of Investigating the Nature of the Nebular Red-Shift' by Edwin Hubble and Richard C. Tolman

"Our conclusions as to the present status of nebular counts can therefore be summarized by stating that it might be possible to explain the results on the basis of either a static homogeneous model with some unknown cause for the red-shift or an expanding homogeneous model with the introduction of effects from spatial curvature which seem unexpectedly large but may not be impossible. This statement must be made very tentatively, however, and may need serious modification in the light of further counts, of new auxiliary data for treating the counts, or of better analysis of the present data."
Merrit
4 / 5 (3) Mar 07, 2018
If the velocity of our solar system is mainly due to its orbit rather than the overall velocity of the galaxy, then over time the CMB will appear differently and we should be able to tell.
barakn
5 / 5 (3) Mar 07, 2018
The orbit of of the solar system around the galaxy takes 230 million years, so "over time" is relative.
Da Schneib
5 / 5 (2) Mar 07, 2018
Interesting. So basically they're going to extremely carefully check the CMB frequency peak in all directions, then see if there's evidence of a dipole (one direction higher than another), then see if it matches with the temperature dipole. That's going to be pretty hard to do.
antialias_physorg
3.9 / 5 (7) Mar 07, 2018
Because the CMB is leftover energy from the Big Bang—when the entire universe exploded outward from a single point

I really wished they'd stop talking of the big bang as an explosion in these PR blurbs but instead would refer to it as an expansion/inflation. 'Explosion' seems to suggest it exploded *in* to something (some available space) - but that's not what happened at all. If it were the CMBR would look vastly different.
fthompson495
1 / 5 (1) Mar 07, 2018
Dark energy is the outflow of dark matter associated with our universal black hole.

Our visible universe is in the outflow of a super-supermassive black hole. As ordinary matter falls toward the super-supermassive black hole it evaporates into dark matter. It is the dark matter outflow which pushes the galaxy clusters, causing them to move outward and away from us. The dark matter outflow is dark energy.

The galaxy clusters which have been pushed for longer than we have are accelerating outward and away from us. We are accelerating outward and away from the galaxy clusters which have been pushed for less time than we have. From our perspective most of the galaxy clusters are accelerating away from us.
milnik
1 / 5 (2) Mar 07, 2018
I think that these people, who brought the news from the universe that something had broken out and that everything that is now exists, flew out of the point, which means everything came from nothing, really or schizophrenics, or have some hidden intention to exclude the entire human race. It's a wonder that there are so many contaminated scientists who believe in it. Even more dangerous and more stupid is that they are now imagining that the universe has one side warmer than the rump. So they realized that the Hubble formula had sunk and now it has to be invented more recently. These scientists do not know that grandfather BB is now 13.8 billion years old and has chosen for himself one half of the universe, and as an old man, he put out fire and heated, so it's warmer there. I'm surprised that your specialists are not visiting grandfather BB and to see if this is true.
granville583762
3.4 / 5 (5) Mar 07, 2018
CMB - an expanding bubble
It looks like a hot air bubble. Relatively hot bubbles of tenuous gas rise in the galactic filaments, so why not in the cosmic background radiation, it is after all an expanding bubble from its conception 15billion years ago.

.
Da Schneib
4 / 5 (4) Mar 07, 2018
I really wished they'd stop talking of the big bang as an explosion in these PR blurbs but instead would refer to it as an expansion/inflation. 'Explosion' seems to suggest it exploded *in* to something (some available space) - but that's not what happened at all. If it were the CMBR would look vastly different.
It would help to say that the currently visible universe expanded from the size of a pea to the size we see it now. That's what they originally meant, but someone left out the part that it's only the current visible universe that was that small from it when it was originally written. Popular science articles and books have been repeating it ever since, unfortunately.
tallenglish
not rated yet Mar 08, 2018
Is the apparent sine wave in that picture just for effect or is the heat polarity actually like that. Makes me wonder if that heat difference is just a result of the universe being inherently spherical/circular and spinning - i.e. leading credance to the idea we are inside a mega-massive black hole or bubble universe in a multiverse and our universe is spinning. Giving everything else does it wouldn't be a hard stretch to believe.
granville583762
4 / 5 (4) Mar 08, 2018
In a vacuum, spherical body's "background radiation" convection currants rise and fall just as they rise and fall in the earth's molten core.
granville583762
5 / 5 (3) Mar 08, 2018
Georges Lemaitre's Cosmic Egg

In 1927 the Roman Catholic priest Georges Lemaitre developed his theory of the expanding Universe and called it the Cosmic Egg, with an escape velocity of a light radius star. Georges Lemaitre did not call it a bigbang.
I really wished they'd stop talking of the big bang as an explosion in these PR blurbs but instead would refer to it as an expansion/inflation. 'Explosion' seems to suggest it exploded *in* to something (some available space) - but that's not what happened at all. If it were the CMBR would look vastly different.
It would help to say that the currently visible universe expanded from the size of a pea to the size we see it now. That's what they originally meant, but someone left out the part that it's only the current visible universe that was that small from it when it was originally written. Popular science articles and books have been repeating it ever since, unfortunately.

milnik
1 / 5 (2) Mar 08, 2018
Georges Lemaitre
may have suffered a stroke because the sperm hit his head because he was under celibacy. Others accepted his fatamorgan because he was influential as a priest. But now we have to ask ourselves: what are the heads and what is in them, and they have turned themselves into that head, something that does not correspond with anything that is related to their origin and the purpose of existence as a human being. For me, such people, who think and who are convinced of such stupid, unnatural and idiotic settings, are just human "bosons" that happen by chance, and they do not even know why.
Again, I want to ask you a question, and it explains all this about this kind of hollow discussion:
 WHY OUR MOON (AND MANY MOONS AROUND OTHER PLANETS) HAVE ONE OF OWN SIDE TURNS TOWARDS A
EARTH?
If science is not able to explain it, everything else is a consequence of illogical, unnatural and fictional theories and imagination.
IMP-9
3 / 5 (6) Mar 08, 2018
If the velocity of our solar system is mainly due to its orbit rather than the overall velocity of the galaxy, then over time the CMB will appear differently and we should be able to tell.


The "orbital dipole" is actually used to calibrate instruments like WMAP and Planck. It's a useful effect in that regard. The orbital dipole is about an order of magnitude smaller than the measured CMB dipole.
cantdrive85
2 / 5 (4) Mar 11, 2018
The CMB dipole is the end of BB pseudoscience as we know it. The acolytes just don't get it though.
RobertKarlStonjek
not rated yet May 04, 2018
Please note that the infinite universe is not necessarily a requirement of the Steady state nor is excluded from a Big Bang Model.

I'm not aware of any Steady State Model that assumes a finite universe, but a finite curved universe would be acceptable for most if not all steady state models to date.

As for the infinite universe I point to UCLA's Cosmology FAQ in which they explain how the infinite universe has a local Big Bang:
http://www.astro....int.html

Since the measurement of the curvature of the Universe showed it was dead flat around half of all cosmologists now accept that the universe has an infinite extension and that only a fraction of it started off in the Big Bang.

It is also worth noting that there is at least one star older than the purported age of the universe, though within the error bars of the BB. However the probability that the oldest star in the Universe is found within a clearly visible range of Earth is negligible

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