Lisa Randall, a renowned Harvard cosmologist and popularizer of science, talks about why humanity shouldn't worry about the possible end of the universe and explains how cosmology can help us find brothers in mind.
Professor Randall is today considered one of the leading experts in string theory, particle physics and cosmology. Yesterday she gave a lecture at the St. Petersburg part of the Geek Picnic festival. She talked about how such different things as dark matter and dinosaurs are related, and how this mysterious substance affects the life and evolution of the universe.
Lisa, in recent years our understanding of the life of the early Universe has significantly expanded, including thanks to the discoveries of the LIGO gravitational observatory. Will such devices help us understand what happened before the Big Bang?
- I do not think that we will ever be able to see not only what happened before the Big Bang, but also the first moments of the life of the Universe. This is impossible from the point of view of how observation devices work and what was happening at that time in the universe.
Observations of events before the Big Bang seem even less likely and more difficult. Of course, we can speculate about this and formulate several theories, however, even the most interesting and consistent hypotheses will not be equivalent to the real answer to this question.
You tried to find hidden dimensions and parallel worlds at the Tevatron collider. Are there any chances of their existence, and is it worth looking for them with the help of gravitational observatories or other instruments?
- Of course, this is not really my specialization, but I can say that these searches are being conducted even now. Our colleagues working with the Large Hadron Collider agreed to test several similar theories that were developed by me and my associates.
Indeed, we have not yet found any traces of the existence of "extra" dimensions, as well as some "new physics" that goes beyond the existing theories. This may be due to the fact that the LHC did not reach the capacity where their traces begin to manifest themselves.
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If we reach higher energies, then traces of such worlds can appear even within the framework of the classical Standard Model. We do not know if there is something outside of it, but I am sure that in this area we will have a lot of discoveries.
Gravitational observatories, it seems to me, are unlikely to help us in search of traces of parallel universes or other dimensions. On the other hand, they can discover signals of an incomprehensible nature, the source of which cannot be recognized as a single cluster of visible matter.
In other words, if we persist enough and for a long time to observe the gravitational Universe, perhaps we will learn something new about dark matter.
The first discoveries of LIGO indicate that an unusually large number of pairs of black holes are present in the Universe around us. Have scientists been able to find an explanation for this, or is there not enough data for this?
- We are just now trying to understand why this is so - we do not yet have an answer to this question. It will be extremely interesting to know if such black holes appear inside initially dense clumps of matter, such as the nuclei of large galaxies or globular clusters of stars, or in more isolated corners of space.
Lisa Randall - American theoretical physicist / Festival della Scienza / Lisa Randall_12.
We are now looking for a way to test whether the tidal forces generated by nearby objects can influence the behavior of the black holes themselves, if the entire system is dense enough.
- Will they help resolve the current debate over how fast the universe has expanded in the past and is growing now?
- I don't think that LIGO or any other gravitational wave detectors will help find the answer to this question. This will require observation of other types of "echo" of the Big Bang or the discovery of new ways of measuring the Hubble constant. They will help you check those values that were calculated in other ways.
For example, the data currently collected by the GAIA probe, which observes a billion stars in the Galaxy, will be of great help in solving this problem.
Will the Universe end its existence and is it important for us to understand when and how this will happen?
- To be honest, I hardly understand such questions. Of course, the life of the universe will end sooner or later. Most likely, it will expand to such extent that complete stasis will occur in it - no events will happen anymore. On the other hand, we can only talk about this if we fully understand how the universe works today.
From a practical point of view, we, of course, do not care - I do not think that humanity will make it to this time. We are unlikely to be able to answer exactly when the universe will stop. We can say that we are lucky - we will not live to see this momentous moment!
Will cosmology help us understand whether extraterrestrial life exists?
- More likely no than yes. Such questions can only be answered with the help of real observations, not theories or calculations. On the other hand, modern cosmological theories do say that other potentially habitable planets, galaxies, and possibly universes do exist.
We can only try to understand from a theoretical point of view what exactly is needed for the origin of life, but without discovering the real "building blocks of life" in any of their forms, we will never be able to say for sure whether we are alone in the Universe or not.