Papers by marios christodoulou
Physical Review Letters
The quest for complete observables in general relativity has been a long-standing open problem. W... more The quest for complete observables in general relativity has been a long-standing open problem. We employ methods from descriptive set theory to show that no complete observable on rich enough collections of spacetimes is Borel definable. In fact, we show that it is consistent with the Zermelo-Fraenkel and dependent choice axioms that no complete observable for rich collections of spacetimes exists whatsoever. In a nutshell, this implies that the problem of observables is to "analysis" what the Delian problem was to "straightedge and compass." Our results remain true even after restricting the space of solutions to vacuum solutions. In other words, the issue can be traced to the presence of local degrees of freedom. We discuss the next steps in a research program that aims to further uncover this novel connection between theoretical physics and descriptive set theory.
Determination of cannabinoids in human cerumen samples by use of UPLC-MS/MS as a potential biomarker for drug use
Journal of Pharmaceutical and Biomedical Analysis
The Astronomical Journal
In the search for life in the cosmos, NASA’s Transiting Exoplanet Survey Satellite (TESS) mission... more In the search for life in the cosmos, NASA’s Transiting Exoplanet Survey Satellite (TESS) mission has already monitored about 74% of the sky for transiting extrasolar planets, including potentially habitable worlds. However, TESS only observed a fraction of the stars long enough to be able to find planets like Earth. We use the primary mission data—the first two years of observations—and identify 4239 stars within 210 pc that TESS observed long enough to see three transits of an exoplanet that receives similar irradiation to Earth: 738 of these stars are located within 30 pc. We provide reliable stellar parameters from the TESS Input Catalog that incorporates Gaia DR2 and also calculate the transit depth and radial velocity semiamplitude for an Earth-analog planet. Of the 4239 stars in the Revised TESS HZ Catalog, 9 are known exoplanet hosts—GJ1061, GJ1132, GJ3512, GJ685, Kepler-42, LHS1815, L98-59, RRCae, and TOI700—around which TESS could identify additional Earth-like planetary c...
Classical and Quantum Gravity
Gravity mediated entanglement (GME) has been proposed as the first experimentally testable signat... more Gravity mediated entanglement (GME) has been proposed as the first experimentally testable signature of quantum gravity. However, to what extent the effect is due to quantum gravity is under debate. In this note, we argue in several ways that the observation of GME does indeed tell us something new about gravity compared to previous experiments. In particular, we consider a quantum reference frame treatment of the experiment that allows us to pinpoint the single degree of freedom responsible for the effect. We also discuss the relevance of the Newtonian limit, the longitudinal/transverse decomposition of the field, and the local operations and classical communication theorem. Our conclusion is that experiments trying to detect GME would be interesting because (a) either positive or negative results would be able to falsify several theories (b) observation of GME would represent something truly novel.
arXiv (Cornell University), Nov 28, 2022
The study of indefinite causal order has seen rapid development, both theoretically and experimen... more The study of indefinite causal order has seen rapid development, both theoretically and experimentally, in recent years. While classically the causal order of two timelike separated events A and B is fixed-either A before B or B before A-this is no longer true in quantum theory. There, it is possible to encounter superpositions of causal orders. In light of recent work on quantum reference frames, which reveals that the superposition of locations, momenta, and other properties can depend on the choice of reference frame or coordinate system, the question arises whether this also holds true for superpositions of causal orders. Here, we provide a negative answer to this question for quantum diffeomorphisms. First, we provide an unambiguous definition of causal order between two events in terms of worldline coincidences and the proper time of a third particle. Then, we show that superpositions of causal order defined as such cannot be rendered definite even through the most general class of coordinate transformations-quantum-controlled, independent diffeomorphisms in each branch. Finally, based on our results, we connect the information theoretic and gravitational perspectives on indefinite causal order.
arXiv (Cornell University), Mar 1, 2018
Transition de géométrie en Gravité Quantique à Boucles Covariante de Marios CHRISTODOULOU Dans ce... more Transition de géométrie en Gravité Quantique à Boucles Covariante de Marios CHRISTODOULOU Dans ce manuscrit, nous présentons un mise en place et calcul d'un observable physique dans le cadre de la Gravité Quantique à Boucles covariante, pour un processus physique mettant en jeu la gravité quantique de façon non-perturbatif. Nous considerons la transition d'une région de trou noir à une région de trou blanc, traitée comme une transition de géométrie assimilable à un effet de tunnel gravitationnel. L'observable physique est le temps caractéristique dans lequel ce processus se déroule. L'accent est mis sur le cas pertinent de géometrie Lorentzienne à quatre dimensions. Nous commençons par une dérivation formelle de haut-enbas, allant de l'action de Hilbert-Einstein au ansatz qui definit les amplitudes de l'approche covariante de la Gravité Quantique à Boucles. Nous prenons ensuite le chemin de bas-en-haut, aboutissant à l'image d'une integrale de chemin du type somme-de-geometries qui émerge à la limite semi-classique, et discutons son lien étroite avec une integrale de chemin basé sur l'action de Regge. En suite, nous expliquons comment construire des paquets d'ondes décrivant des géométries spatiales quantiques, plongées dans un espace-temps quantique de signature Lorentzienne, à partir d'une hypersurface continue plongée dans un espace-temps Lorentzienne. Nous montrons que lors de la mise en oeuvre de ces outils, nous avons une estimation simple des amplitudes decrivant des transitions de géometrie de façon probabiliste. Nous fournissons une formulation indépendante de choix d'hypersurface de l'espace-temps Haggard-Rovelli, qui modélise l'espace-temps classique entourant la région de transition de géométrie. Nous construisons un mise en place basée sur l'espace-temps HR, où une approche d'intégrale de chemin peut être appliquée naturellement. Nous proposons une interprétation des amplitudes de transition et définissons les observables classiques et quantiques pertinents pour ce processus. Nous procédons à une derivation d'une expression explicite, analytiquement bien-définie et finie, pour une amplitude de transition décrivant ce processus. Nous utilisons ensuite l'approximation semi-classique pour estimer la dépendance, vis-à-vis de la masse, du temps characteristique de la processus, pour une classe d'amplitudes et pour un choix arbitraire des conditions de borne. Nous terminons en discutant l'interprétation physique de nos résultats et de futurs directions de recherche.
arXiv (Cornell University), Jul 4, 2022
Detecting gravity mediated entanglement can provide evidence that the gravitational field obeys q... more Detecting gravity mediated entanglement can provide evidence that the gravitational field obeys quantum mechanics. We report the result of a simulation of the phenomenon using a photonic platform. The simulation tests the idea of probing the quantum nature of a variable by using it to mediate entanglement, and yields theoretical and experimental insights. We employed three methods to test the presence of entanglement: Bell test, entanglement witness and quantum state tomography. We also simulate the alternative scenario predicted by gravitational collapse models or due to imperfections in the experimental setup and use quantum state tomography to certify the absence of entanglement. Two main lessons arise from the simulation: 1) which-path information must be first encoded and subsequently coherently erased from the gravitational field, 2) performing a Bell test leads to stronger conclusions, certifying the existence of gravity mediated nonlocality.
arXiv (Cornell University), Oct 26, 2020
We provide a mathematically and conceptually robust notion of quantum superpositions of graphs. W... more We provide a mathematically and conceptually robust notion of quantum superpositions of graphs. We argue that, crucially, quantum superpositions of graphs require node names for their correct alignment, which we demonstrate through a no-signalling argument. Nevertheless, node names are a fiducial construct, serving a similar purpose to the labelling of points through a choice of coordinates in continuous space. Graph renamings, aka isomorphisms, are understood as a change of coordinates on the graph and correspond to a natively discrete analogue of continuous diffeomorphisms. We postulate renaming invariance as a symmetry principle in discrete topology of similar weight to diffeomorphism invariance in the continuous. We explain how to impose renaming invariance at the level of quantum superpositions of graphs, in a way that still allows us to talk about an observable centred at a specific node.
Evaluation of different extraction procedures for the quantification of seven cannabinoids in cannabis-based edibles by the use of LC-MS
Journal of Food Composition and Analysis
Molecules
Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ab... more Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ability to prevent many diseases mainly due to the presence of polyphenolic compounds. In this study, we explored, for the first time, the anti-cancer properties of Cypriot carobs. We produced extracts from ripe and unripe whole carobs, pulp and seeds using solvents with different polarities. We measured the ability of the extracts to inhibit proliferation and induce apoptosis in cancer and normal immortalized breast cells, using the MTT assay, cell cycle analysis and Western Blotting. The extracts’ total polyphenol content and anti-oxidant action was evaluated using the Folin–Ciocalteu method and the DPPH assay. Finally, we used LC-MS analysis to identify and quantify polyphenols in the most effective extracts. Our results demonstrate that the anti-proliferative capacity of carob extracts varied with the stage of carob maturity and the extraction solvent. The Diethyl-ether and Ethyl aceta...
Observing entanglement generation mediated by a local field certifies that the field cannot be cl... more Observing entanglement generation mediated by a local field certifies that the field cannot be classical. This information-theoretic argument is at the heart of the race to observe gravity-mediated entanglement in a `table-top' experiment. Previous derivations of the effect assume the locality of interactions, while using an instantaneous interaction to derive the effect. We correct this by giving a first principles derivation of mediated entanglement using linearised gravity. The framework is Lorentz covariant -- thus local -- and yields Lorentz and gauge invariant expressions for the relevant quantum observables. For completeness we also cover the electromagnetic case. An experimental consequence of our analysis is the possibility to observe *retarded* mediated entanglement, which avoids the need of taking relativistic locality as an assumption. This is a difficult experiment for gravity, but could be feasible for electromagnetism. Our results confirm that the entanglement is ...
Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator i... more Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator in Loop Quantum Gravity, we show that the dimension of the space of the quadrivalent, diffeomorphism invariant states with no zero-volume nodes describing a region with total volume smaller than V, has finite dimension, bounded by V V. This allows us to introduce the notion of "volume entropy" for this phase space: the von Neumann entropy associated to the measurement of volume.
ArXiv, 2020
We provide a robust notion of quantum superpositions of graphs. Quantum superpositions of graphs ... more We provide a robust notion of quantum superpositions of graphs. Quantum superpositions of graphs crucially require node names for their correct alignment, as we demonstrate through a non-signalling argument. Nevertheless, node names are a fiducial construct, serving a similar purpose to the labelling of points through a choice of coordinates in continuous space. We explain that graph renamings are, indeed, a natively discrete analogue of diffeomorphisms. We show how to impose renaming invariance at the level of graphs and their quantum superpositions.
Natural Products as Scaffolds for the Modulation of Topoisomerase I
Two natural products, Camptothecin (1, Figure 1), an alkaloid isolated from the Chinese tree Camp... more Two natural products, Camptothecin (1, Figure 1), an alkaloid isolated from the Chinese tree Camptotheca acuminate Dence,1 and Evodiamine (2), an alkaloid isolated from the dried fruit of Evodia rutaecarpa (Juss.) Benth (E. rutaecarpa),2 are characterized by antitumoral activity, targeting the DNA topoisomerase I,3-5 an ubiquitous and essential enzyme for topological DNA modification during a number of critical cellular process in mammals.6 However, their therapeutic application is hindered because of poor aqueous solubility and high in vivo hepatoxicity. Subsequently, the structural modification of the natural Camptothecin and Evodiamine is crucial for the improvement of their pharmacological and pharmacokinetic profile.7-10 Figure 1. Structure of camptothecin and evodiamine and images taken from modeling studies.11 In our interest, for the synthesis of various derivatives of the natural compounds we focused on position 7 of the Camptothecin, and on position 5 of the Evodiamine moiety (Figure 2). Experimental In the case of Camptothecin, the reactivity of position 7 gave us the possibility to obtain 7-hydroxymethyl camptothecin that by reaction with hydrobromic acid resulted in the corresponding bromoderivative. We then turned our attention toward the formation of C-S bond that resulted as a not trivial issue. The solution of the problem gave us the possibility to obtain 3 different compounds stable enough to be submitted to different biological assays. Antiproliferative activity and topoisomerases inhibition were investigated and the results moved us to study the cellular response to the DNA damage and their influence on angiogenesis. With a similar approach a library of 11 compounds has been prepared by introduction of a carboxylic group at position 5 of evodiamine. The biological data have been compared with the suggestion deriving from modeling studies. Figure 2. Results and discussion In the case of camptothecin derivatives, the results of cellular studies and the molecular modeling analysis indicated that the 7-modified camptothecin derivatives fully maintained the biological activity and the same feature of drug-target interaction of the natural compound. This conclusion is also supported by the biochemical characterization indicating a comparable ability to induce DNA damage. These observations support the view that the 7-position is favourable for safe introduction of suitable side chains without detrimental effects. In the case of evodiamine derivatives the preliminary results regarding the antoproliferative activity require further investigation that are ongoing. References [1] Wall, M.E., Wani, M.C., Cook, C.E., Palmer, K.H., McPhail, A.T., Sim, G.A., J. Am. Chem. Soc., 88 (1966), 3888-3890. [2] Asahina, A., Kashiwaki, K., Yakugaku Zasshi, 405 (1915), 1293; Chem. Abstr., 10 (1916), 607. [3] Hsiang, Y.H., Hertzberg, R., Hetch, S.M., Liu, L.F., J. Biol. Chem., 260 (1985), 14873-14878. [4] Liu, L.F., Desai, S.D., Li, T.K., Mao, Y., Sun, M., Sim, S.P., Ann. N. Y. Acad. Sci., 922 (2000), 1-10. [5] Dong, G., Sheng, C., Wang, S., Miao, Z., Yao, J., Zhang, W., J. Med. Chem., 53 (2010), 7521-2531. [6] Pommier, Y., Nat. Rev. Cancer, 6 (2006), 789-802. [7] Driver, R.W., Yang, L.X., Mini-Rev. Med. Chem., 5 (2005), 425\u2013439. [8] Li, Q.Y., Zu, Y.G., Shi, R.Z., Yao, L.P., Curr. Med. Chem., 13 (2006), 2021\u20132039. [9] Thomas, C.J., Rahier, N.J., Hecht, S.M., Bioorg. Med. Chem., 12 (2004), 1585\u20131604. [10] Chen, Z., Hu, G., Li, D., Chen, J., Li, Y., Zhou, H., Xie, Y., Bioorg. Med. Chem., 17 (2009), 2351\u20132359. [11] The image of the docked position of evodiamine has been taken from Dong, G., Sheng, C.; Wang, S., Miao, Z., Yao, J., Zhang, W. J. Med. Chem 53 (2010), 7521-7531
arXiv: General Relativity and Quantum Cosmology, 2018
Quantum fluctuations of the metric provide a decay mechanism for black holes, through a transitio... more Quantum fluctuations of the metric provide a decay mechanism for black holes, through a transition to a white hole geometry. Old perplexing results by Ambrus and H\'aj\'i\v{c}ek and more recent results by Barcel\'o, Carballo-Rubio and Garay, indicate a characteristic time scale of this process that scales linearly with the mass of the collapsed object. We compute the characteristic time scales involved in the quantum process using Lorentzian Loop Quantum Gravity amplitudes, corroborating these results but reinterpreting and clarifying their physical meaning. We first review and streamline the classical set up, and distinguish and discuss the different time scales involved. We conclude that the aforementioned results concern a time scale that is different from the lifetime, the latter being the much longer time related to the probability of the process to take place. We recover the exponential scaling of the lifetime in the mass, a result expected from na\"ive semicl...
In the published article, there was an error regarding the affiliations for Carlo Rovelli. As wel... more In the published article, there was an error regarding the affiliations for Carlo Rovelli. As well as having affiliations 3 and 4, he should also be assigned the affiliation ‘CPT, Aix Marseille Univ, Université de Toulon, CNRS, Marseille, France’. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.
Plant Disease, 2021
In June 2017, three vineyards were surveyed in the regions of Droushia (30-year-old, cv Mavro), I... more In June 2017, three vineyards were surveyed in the regions of Droushia (30-year-old, cv Mavro), Ineia (50-year-old, cv Xynisteri), and Lemona (15-year-old, cv Carignan) at the province of Paphos, Cyprus, with dieback incidence of 22%, 32%, and 14%, respectively. More specifically, affected grapevines exhibited severe dieback symptoms in spur and cordon positions, related to perennial cankers and internal brown discoloration. Thirty symptomatic samples, were surface-sterilized (95% ethanol) and wood chips were plated on potato dextrose agar (PDA), amended with streptomycin (500 μg/ml) at 25 °C for 3-5 days. Based on colony morphology (white to creamy color, with sparse aerial mycelium) and conidia production, nine Diaporthe-like isolates were obtained. For species identification, the internal transcribed spacer (ITS) region and β-tubulin (BT) genes were amplified using the primer pairs ITS1/ITS4 and Bt2a/Bt2b, respectively (Úrbez-Torres et al. 2008). Sequences of the isolates P101b, ...
Physical Review D, 2021
At the end of the Hawking evaporation the horizon of a black hole enters a physical region where ... more At the end of the Hawking evaporation the horizon of a black hole enters a physical region where quantum gravity cannot be neglected. The physics of this region has not been much explored. We characterise its physics and introduce a technique to study it.
Time at the Planck scale (∼10−44s) is an unexplored physical regime. It is widely believed that p... more Time at the Planck scale (∼10−44s) is an unexplored physical regime. It is widely believed that probing Planck time will remain for long an impossible task. Yet, we propose an experiment to test the discreteness of time at the Planck scale and show that it is not far removed from current technological capabilities.
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Papers by marios christodoulou