Yes, the Planck satellite has a slightly smaller estimate for the distance to the horizon.JDamian88 said:http://www.iflscience.com/space/the...is-closer-than-scientists-previously-thought/
Hey, guys! I'm new in this forum and I found this interesting article.
Damian
In a half-century history of studies on detection of CνB, interesting proposals have been presented. However, with the current available technology, none of the proposed methods that are described in this review are close to be reality, except for the promising Project 8 and PTOLEMY experiment, unless local neutrino overdensity is much larger than expected.
Thanks for the explanation about neutrinos and the articles! Now I understand it betterChalnoth said:Yes, the Planck satellite has a slightly smaller estimate for the distance to the horizon.
The claim that neutrinos may extend the observable limit out to 46 billion light years isn't right, though. Because neutrinos travel through matter very efficiently at lower energies, measuring the cosmic neutrino background would provide an image of a significantly younger universe than the CMB offers. But the dynamics of the early universe expansion are such that things emitted earlier don't necessarily come from further away. See here:
https://arxiv.org/pdf/0907.2887.pdf
Because massive neutrinos travel a little bit slower than the speed of light, the CNB surface is actually a little bit closer than the CMB surface.
There are also, unfortunately, practical problems with actually observing the Cosmic Neutrino Background. Namely, the CNB is already extremely low-temperature (colder than the CMB: about 1.95K), and neutrinos pass through matter very efficiently at low energies (the lower the energy, the more easily they pass through matter). So to measure the CNB, we'd be looking at the very rare signals coming from the rare collisions of these CNB neutrinos with normal matter, and each individual collision would transfer so little energy to the normal matter that it'd be very difficult to measure at all. See here, for example:
http://journal.frontiersin.org/article/10.3389/fphy.2014.00030/full
Quoted from the conclusion:
The paper seems perfectly reasonable and non-controversial to me. My main criticism was with the neutrino comments in the article, which don't appear in the paper (though the paper does make an offhand comment about neutrinos allowing us to see further, which as I note above isn't correct).Fervent Freyja said:Journal Reference for news article you posted (which did not cite it at all, only a link to another news article) : http://www.isaacpub.org/PaperInformations.aspx?ids=4&pid=1062&jqy=Volume 3, Number 1, November 2016&JShortName=AdAp
@Chalnoth, is this journal publisher trustworthy- I haven't came across them before? How credible is this paper to you?
Chalnoth said:The paper seems perfectly reasonable and non-controversial to me. My main criticism was with the neutrino comments in the article, which don't appear in the paper (though the paper does make an offhand comment about neutrinos allowing us to see further, which as I note above isn't correct).
I agree, but as I understand the particle horizon (theoretical observable limit), it postulates a massless particle traveling unhindered from cosmic time zero. Using the Planck 2013 data, it puts the particle horizon at around 46.3 Glyr. With the WMAP data, the distance was 46.7 Glyr.Chalnoth said:Yes, the Planck satellite has a slightly smaller estimate for the distance to the horizon.
The claim that neutrinos may extend the observable limit out to 46 billion light years isn't right, though. Because neutrinos travel through matter very efficiently at lower energies, measuring the cosmic neutrino background would provide an image of a significantly younger universe than the CMB offers. But the dynamics of the early universe expansion are such that things emitted earlier don't necessarily come from further away. See here:
https://arxiv.org/pdf/0907.2887.pdf
Scientists use various methods such as measuring the distance between galaxies and observing the cosmic microwave background radiation to determine that the universe is indeed shrinking.
The shrinking of the universe challenges our current understanding of the universe and raises new questions about its ultimate fate. It also has implications for the expansion rate of the universe and the existence of dark energy.
The exact amount of the universe's shrinkage is still being studied and debated by scientists. Some estimates suggest that it may have shrunk by a few percentage points, while others propose a larger shrinkage of up to 10%. Further research and data are needed to determine the exact amount.
No, the shrinking of the universe is happening on a much larger scale and will not have any direct impact on Earth. However, it does have implications for the overall structure and fate of the universe.
It is currently unknown if the universe is shrinking uniformly or if certain regions are shrinking at a faster rate than others. This is an area of ongoing research and further data and observations are needed to fully understand the dynamics of the universe's shrinkage.