'This is the way the world ends, not with a bang but a whimper'

Professor Farseem Mannan Mohammedy is National Outreach Coordinator and Chair of the National Astronomy Education Coordinating Team for Bangladesh, both under the International Astronomical Union. A professor of Electrical and Electronic Engineering at Bangladesh University of Engineering and Technology (BUET), he is also the General Secretary of Bangladesh Astronomical Society and Society for the Popularization of Science, Bangladesh.

In a recent interview with The Business Standard, Professor Farseem opened up about how the universe came into being and how it will end, aliens and the possibility of a real life Star Wars.

The Business Standard (TBS): Over the years, we have come to know that the universe came into being after the Big Bang took place about 14 billion years ago. But what was there before the Big Bang and what started it in the first place?

Farseem Mannan Mohammedy (FMM): The Big Bang occurred 13.7 billion years ago. We have quite a few clear and unambiguous observational data to support that. What happened before is a matter of scientific speculation. However, there are certain scenarios involving the Inflationary epoch which occurred at very early stages of the Universe.

In physical cosmology, the Inflationary epoch was the period in the evolution of the early universe when, according to Inflation theory, the universe underwent an extremely rapid exponential expansion. The problem is that there are multiple scenarios, sometimes they conflict with each other, and it is hard to derive unambiguous evidence to clearly see which one is "causing" what.

One of the early proponents of Inflation, Paul Steinhardt, started debating the success of the various scenarios. In this respect, he referred to some foundational questions of science regarding falsifiability and the like.

The main thing was which scenario could answer for the happenings of events "before" the Big Bang and at the same time will show an evidence which is clear and unambiguous at the present time. But unfortunately there are no such findings, yet.

It is also important to realize that though there are no clear answers, the possibility of the existence of multiple solutions is also a positive step.

As opposed to no answer, now one can talk about these possibilities. It remains to be seen whether these possibilities will open up any scientific front or if the answer will come from other directions, or a mixture of String theories, inflationary bubbles and tunneling from quantum foam. Only the future knows.

TBS: What is the universe made of? What does it look like? We know about the stars and galaxies and other "Baryonic things" as mentioned in cosmology books. But the books say that these forms only five percent of the total universe. Then what is that rest of the 95 percent made of?

FHM: The Universe is made of Dark Energy (69.3 percent), Dark Matter (25.9 percent and Ordinary matter (4.8 percent). This is our current understanding and is backed by a multitude of observational data. The latest being those from the Planck satellite of the European Space Agency.

We know what ordinary matter is: it's the stuff that we are all made of. We know that Dark Matter exists, but couldn't detect what it is made of, despite the hair-splitting efforts made by scientists all over the world. My book on "Dark Matter" (Prokrity-Porichoy, 2016) discusses Dark Matters.

We have no understanding of Dark Energy yet, only that it is expansive. It pushes out, in contrast to gravity that pulls in. It looks like it's the energy of the vacuum space, but again we are in the "dark".

So we only know less than five percent of things. We know that there exists something about 26 percent, we can observe its presence through its gravitational signature, but it has extremely little interaction with known matter. Hence we don't know for sure what it is.

It sounds disappointing but that's how science works. We knew very few things about the universe a hundred years ago, but now we surely know better. So let us keep our fingers crossed for the next few decades for exciting discoveries.

The universe looks like a sponge from a very, very large scale. There is matter concentrated in filaments and sheets, and there are very large voids too where there are very few galaxies.

Though the Universe looks lumpy, but on a very, very large scale it is still considered to be homogeneous and isotropic.

TBS: Tell us about the aliens. Is there a possibility of a real Star Wars? Or are we the lone stargazers in this universe?

FMM: I don't see any reason for any imminent Star Wars. But that doesn't mean we are alone. There are remarkable advances that we made in the last decades. The plethora of Exoplanets so far discovered shows how varied an alien world can be!

Exoplanets are planets that revolve around other stars. Just like the Earth revolves around the sun. While this is being written, there are more than 4,000 confirmed exoplanets. Some of these planets might fit the conditions of Goldilocks' planet: a planet that harbors the conditions suitable for life.

Something like this Earth, where the conditions are "just right" for life to thrive. So, the existence of exoworlds, where exoplanets go around their central star(s), gives ample space for considering alien life outside the solar system.

Alien life, by the way, doesn't mean alien civilization. An alien microbial colony, a stargazing alien colony and a star-faring space-bound alien spaceship are very different things. There is a famous equation – called the Drake equation – to calculate the number of radio-capable alien civilizations in the Galaxy.

Some astrobiologists calculate it to be just four in the Milky Way. This number is an update that considers the nature of the discovered exoplanets and their host stars.

Actually, one should look for red or yellow dwarf stars and rocky planets to search for Goldilocks' conditions. Also, a very intelligent sentient being might just be lonely, confused, depressive, or simply not be willing to communicate at all.

Alternately, there could be immense hurdles – the Great Filters – in order to reach the level of radio comms. So, it could be that no one is out there to hear us. Or, it could also be that they are watching!

There was a famous paradox, posed by physicist Enrico Fermi, which is about the existence of aliens. Since there are so many possible habitable planets, and given the immensity of the Universe, there could be hundreds of aliens. But, where are they? Why don't we see their spaceships? The answer is still open and I have mentioned a host of possibilities above.

One thing is for sure, we don't have anybody in the Solar System to hear us. There could be microbial life forms in Mars, Titan, Europa, but not more than that. So, prepare to stay low for another millennia!

TBS: Scientists say that the universe is expanding at an accelerated rate.  But is there enough space in the "space" for that?

FMM: Space is expanding at an accelerated rate. The expansion is in all directions. And space is just to itself. It doesn't expand "into" anything. There is only space out there, and that's all there is. Space begets space, so the question is pointless, once you master General Relativity and Cosmology.

TBS: How will the universe ultimately end? Cosmologists use terms like "heat death" or the "big freeze", "big crunch", and "big rip". What are these? Which one of these will be the ultimate cause of the end?

FMM: I have written extensively in my book "Thake Shudhu Ondhokar'' (Prokrity-Porichoy, 2nd edition, 2017) about the end. Also, late Professor Jamal Nazrul Islam has a beautiful book about it titled "The Ultimate Fate of the Universe".

However, Freeman Dyson had the greatest paper ever written on this subject in "Time without end: Physics and Biology in an Open Universe". I think one should read all the three books.

But on a very brief note, here's how it unfolds: The Universe is open ended, verified by the Type I Supernova data, and other concordant relationships among unrelated data. So this is an observational fact. Now one should speculate what should happen, how it should happen. If acceleration continues, almost all galaxies will fade out from our view: they will be so distant that their light won't reach us anymore. New star formation would also cease, since there won't be any hydrogen left. There will be dim stars and black holes and Hawking radiation. Matter will break down if the proton becomes unstable over a very large time scale.

Within the neighborhood, the Andromeda galaxy and our Galaxy will collide, making one large giant galaxy. The Laniakea formation of galaxies, the superstructure of which we are a part of, likely to hold, in some form, over very large time scale, though they will disintegrate eventually.

As such, the end will be like what TS Eliot said "This is the way the world ends, not with a bang but a whimper." By the present reckoning, this is the "bestest" time to live in order to do astronomy as you could still see the lights in the sky and measure it. In the far future, there won't be any except local lights.

TBS: Is the earth going to end at first, or it will perish along with the universe simultaneously? If the end happens, when will this happen?

FMM: The Earth depends on the Sun for everything. Hence, her demise will also depend on the Sun and its stellar evolution path. The standard answer is that as the Sun burns up its hydrogen, the core gets depleted and will eventually have to start burning helium.

During its evolution, it will expand into a phase of the Red Giant. During this phase, the outer envelope of the Sun will most likely engulf the Earth. So that's the end that we are looking for.

But before that, the Earth may face planetary disaster. For example, due to a possible extinction phenomenon (may be due to a rogue meteor, or environmental disaster), the climate as we know will completely change. We may lose almost all surface water in some scenarios. So it will become hellish on Earth even before the Red Giant phase of Earthly demise sets in.

Hence, as you see, though the universe will not "end" in any sense, there is a definite "end" to Earth and her legacy. Sad, eh!

TBS: What will be left after the end? Will there be another universe? Will the universe repeat its course at its ruins?

FMM: I have reiterated before, and in my above mentioned book, there is no "end" to an open and flat universe. The universe will go on expanding forever. That is the current scenario.

What will happen in an open universe? As I mentioned before, and also in my book, most local massive systems, gravitationally bound, will converge on to each other. Everything else will scatter further apart. Resources will be scarce. Things will cool down and get to the flat line of Gibbons-Hawking temperature level.

Locally, within gravity bound environments, things will be slightly better for sentient beings. They could still harness some energy for their intelligence to stay alive. Heat is very important for brain function and basic computation which are absolutely necessary for intelligence.

Freeman Dyson said that intelligent beings could opt for very long hibernations to save energy for living. This is all we know. Whether this universe could tunnel into another one is speculative and is not based on tested evidence whatsoever. By that time, intelligent beings will possibly learn how to tunnel to another universe for survival, before the universe itself tunnels to another, or back to the quantum foam.

In the very long future, there could only be some relict radiation and elementary particles in an open universe. There is a speculation that lonely Boltzmann brains could pop out of the never-ending equilibrium, but that's just an idea.