Ask Ethan: Is it true that there is a hole in the universe?

The very alleged “hole in the Universe” (text in the picture: 6 billion billion light-years from us is a billion-light-year void, in which there is no matter, and which does not emit any radiation).

Of course, the Internet is full of wonderful and scientifically truthful information. But, probably, there are much more sites designed to generate clicks and traffic without taking into account scientific accuracy, and it is sometimes very difficult for a lay person to determine who is who. This week, our reader asked a question about the picture he dug on the Internet above:

Do you know what it is? Have you written about this before?

First, let's figure out what is actually depicted there.



The background of the photo is so rich in stars, because these stars are in our Milky Way. Yes, in our galaxy with a diameter of 100,000 light years. That is, the dark cloud blocking the background starlight should be closer to these stars, so there is no question of any billions of light-years. It is much closer: this object is a cloud of gas and dust, located just 500 light years from us, and it is known as Barnard 68 . At the beginning of the 20th century, astronomer Edward Emerson Barnard compiled a catalog of hundreds of “dark nebulae,” now known as molecular clouds , star cradles, or globules. These are clouds of neutral gas scattered across our galaxy.

The cloud in question is small and relatively close to us:

• It is only 500 light years from us,
• It is about a quarter of a light year,
• Its mass is about two times that of the sun.

Since neutral gas blocks visible light but is transparent to longer wavelengths, you may wonder if you can’t see the stars it obscures in the infrared or radio range.



This is exactly what they did with the help of various instruments managed by the European Southern Observatory. Beyond the cloud, approximately 3,700 obscured stars were found. Moreover, the absorption properties of a neutral gas have informed us a lot of information, including that the inside of the cloud is extremely cold, its temperature is only 16 K (-257 ° C), and the outer layers of the globule indicate the presence of internal decay. Further analysis showed that its inner core collapses into a star in about 200,000 years, which means that we will know where to look for a star close enough to us, formed in isolation from others.

So, no, dear reader, the object in the photo is clearly not a hole in the universe. But, interestingly, in 2007, one scientific work did come out, touting the existence of a hole in the universe.



Imagine that there really is a hole in the universe, as stated in the picture. If there were a “void the size of a billion light-years, in which there is no matter, and which does not emit any radiation” - how would this be manifested? We would see this as a cold region in relict radiation (the image of which was obtained by WMAP or Planck), since a change in the gravitational field caused by such a void (technically, the Sachs-Wolf effect ) would lead to a slight decrease in the temperature in cosmic radiation. But this cold section would have to coincide with the region free of galaxies, and confirmation of this would require deep and wide observation.

What actually found the team of Rudnick, Shea and Williams [Rudnick, Shea and Williams], who studied the region of the sky , is a region of space in which the number of galaxies is 20-45% below average, which can be explained in several ways.



Naturally, in space there are places where the matter - stars, gas, dust, even dark matter - is much less than the average amount. Since then, other voids of comparable size have been discovered.. You can, of course, call such a region, completely free from galaxies, a “hole in the Universe,” as all kinds of reporters and press releases do. But it can be something much less spectacular - a slight decrease in density compared to a large fraction of the universe. And until we make a special three-dimensional space map of the region of interest to us (using spectroscopy to confirm the redshift of the observed galaxies), we will not know exactly how our galaxies are located. But in principle, there may not be any emptiness at all, let alone a region completely free from all matter.



This leads us to a big problem in the transfer of scientific information - since the above picture was seen by millions of people, and no more than tens of thousands will see the correct explanation of the phenomenon and all the subtleties of what is happening. What to do with people and organizations actively destroying the knowledge of humanity? After all, the opposite of knowledge is not ignorance, but false information pretending to be knowledge.

If you bring scientific information to the world, your first duty is to accurately describe what we know about the universe. And if you do not know what we know, you must obtain this information. I take part in the clarification with pleasure - and you take part by sending your questions. But writers, journalists, and other people transmitting information should be meticulous and diligent, and readers should carefully select the sources of information. Otherwise, it will not be possible to draw a line between scientific truth and just some information, the result of which you want to call "science", regardless of whether it really is science.