Can Self-Replicating Species Flourish in the Interior of a Star? Luis A. Anchordoqui and Eugene M. Chudnovsky Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, USA (Dated: June 2020) The existing view of biological life is that it evolves under suitable conditions in the low-temperature world of atoms and molecules on the surface of a planet. It is believed that any plausible extraterrestrial form of life must resemble the life on Earth that is ruled by biochemistry of nucleic acids, proteins, and sugars. Going against this dogma, we argue that an advanced form of life based upon short-lived species can exist inside main-sequence stars like our Sun. Conventional wisdom states that the search for ex- it is unknown, we will not speculate about the intricate olife calls for carbon-based organisms, operating in a series of bionuclear reactions that can satisfy hypothesis water-based medium, with higher forms (perhaps) me- 2. tabolizing oxygen. All forms of life on Earth share this It has long been suspected that any early universe same basic biochemistry. However, biological molecules phase transition occurring after inflation (say with sym- are not stable in a thermodynamic sense [1]. Life can be metry breaking temperature T ) may leave behind topo- thought-out as a dynamical hypercycle (DNA encode c logical defects [2]. This is because when the system cools proteins, proteins help DNA to self-replicate, DNA en- down below T there is some order parameter field mul- code proteins, . ) that can survive indefinitely as long c tiplet φ which picks up a non-zero vacuum expectation as free energy is available for it, and as long as self- value 0 φ 0 = φ . If this were the case and the sys- replication goes faster than destruction of information 0 tem hash j a symmetryj i group G, then any operation g G carriers. Mutations in the informational chain provide would transform the vacuum state φ into a degener-2 natural selection and evolution towards more complex ate vacuum state that has expectation value gφ . Now, species. Proteins are different chains of 20 (+2) amino 0 if we identify the subgroup leaving φ invariant with acids. To encode amino acids, one needs a minimum of 0 H = h G hφ = φ G, the vacuum manifold would a triplet RNA/DNA code of 4 nucleotides: A,C,G,U, like 0 be givenf 2 byj the quotientg ⊂ M = G=H, viz. the set of left AAA, AUG, etc. This gives 43 = 64 different combina- cosets gH of H in G. The topology of M character- tions. izes thef typesg of defects. For example, cosmic strings Of course, all this can be totally different for a different would form if the first homotopy group π1(M ) , 1, form of life, but self-replication is a cornerstone of life where 1 stands for the group comprising the identity and it is hard to imagine how any life can be formed alone. Note that this entails M contains closed loops without encoding information. If one accepts that life that cannot be continuously shrunk to a point and so M is merely self-replication with mutations that leads to would not be simply connected. Likewise, monopoles the increasing complexity through natural selection, any would be produced if π2(M ) , 1. Note that for this system capable of such processes can be viewed as a form particular configuration there would be non-shrinkable of life. As an example, self-replicating robots assembling two-dimensional surfaces in M . themselves in the environment that can be vastly differ- ent from the ambient conditions we are used to have long Appealing to our discussion is the formation of com- been considered one such possibility. More concretely, posite defects. This may take place if a theory with symmetry group G undergoes a phase transition (at T ) life needs at the minimum of these three hypotheses: c1 in which φ acquires a vacuum expectation value break- 1. The ability to encode information. ing the theory to a subgroup H G, and after that 2. The ability of information carriers to self-replicate ⊂ there is a second phase transition (at Tc2 ) in which the faster than they disintegrate. field gets a non-zero (but generally smaller) vacuum 3. The presence of free energy: At the minimum expectation value to break the symmetry further into ∆F = T ∆S, needed to constantly create order out K H. One simple example is provided by the SU(2) of the disorder by decreasing entropy S through symmetry⊂ group. In the first stage of symmetry break- self-replication, where T is the temperature of the ing, in which φ becomes non-zero, the symmetry breaks system. down to H = U(1) leading to the formation of ’t Hooft- Armed with this extreme reasoning, we ask whether Polyakov monopoles [3, 4]. In a second stage, the sym- some form of life could flourish deep inside the core metry breaks further into K = Z2 where strings would of main-sequence stars like our Sun. We speculate that form. Remarkably, there is a stable configuration, the it is possible to satisfy hypotheses 1 and 3. Given how bead, in which the magnetic flux of the monopole 4π/e complex and non-obvious is the functioning of the bio- is confined to two stable Z2 strings, each carrying a flux logical cell that we are familiar with, and the fact that of 2π/e [5, 6]. Such string structures with monopole the early path of the biological evolution that has led to beads are so-called “necklaces.” Remarkably, multiple 2 that the strings are produced at the electroweak phase transition and so Tc2 100 GeV, yielding a mass per ∼ } 3 2 6 unit length of string µ c Tc2 10− g=cm. Before proceeding, we pause to∼ note that' for ultrarelativistic particles in thermal equilibrium, the blackbody formula gives the energy density-temperature relation " = CT4, where the constant C depends on the number of degrees of freedom. For the electroweak phase transition, the energy density that must be deposited in the collision region to achieve the conditions for a phase transition, " 1010 GeV=fm3, is 10 orders of magnitude larger than what∼ is currently achieved in collisions at the CERN Large Hadron Collider [11]. In the spirit of [12], we consider superconducting strings (carrying electric currents and generating mag- FIG. 1: Encoding information with cosmic necklaces consisting netic fields) that become magneto-hydro-dynamically of beads on strings (left), and a string double helix resembling frozen into plasma. The evolution process could be- DNA (right) [10]. gin with a single string in the system. Turbulence of the plasma stretches and twists the string loop, cutting it at the intersections, until an equilibrium network of strings can originate from monopoles and connect them string loops develops in which the process of stretching into two- and three-dimensional structures, resembling is balanced by the collapse of string loops due to ten- atoms coupled by chemical bonds [7]. Since information sion. Note that the likelihood of a string being capture needs to be written on a one-dimensional chain to en- by star is quite small. This is because the plasma wind sure easy reading and transcription [8], monopoles and from the star would prevent the string to approach it. antimonopoles of one kind would not be sufficient for A more probable scenario would be to assume that the that purpose. Each string carrying half of the magnetic string is captured during the star formation. The pro- flux that originates on a monopole has to go into anti- cess of star formation begins in weakly ionized clouds 22 3 20 monopole, thus making monopoles and antimonopoles of density in the range 10− . ρ/(g=cm ) . 10− [13]. of one kind alternating in a one-dimensional chain. Such Stars are formed as a result of slow gravitational con- a chain would not carry any information. However, with densation of matter in the high-density regions of the various kinds of monopoles and strings discussed in lit- cloud. In the early stage of this process, neutral matter erature, it is easy to envision more complex sequences contracts together with plasma, and with the magnetic capable of encoding information. For example, two adja- field and strings frozen into it. As the density increases, cent semipoles [9], unlike monopoles, need not have total the degree of ionization falls and the neutral matter de- charge zero and can repel each other instead of moving couples from the plasma. During this stage strings can towards each other and annihilating. Such single- and be left out from the protostar. However, in the course double-chain structures formed by beads on necklaces of further contraction, the protostar becomes thermally are shown schematically in Fig. 1. ionized and recaptures its coupling to the magnetic field The lifetime of such objects can be very short as far and to the strings. The radius of the ionized material 8 as their individual dynamics in vaccum is concerned. It is typically Rion = 10 km. For typical clouds, the dis- can be longer in a plasma of a star (see below) and can persion velocity of the turbulent motion is in the range also be controlled by the metabolic process they encode. 105 . v=(cm=s) . 106 [13]. The force of friction per unit Note in this connection that any biological organism, length of string produced by a superconducting string when considered individually, is unstable.