Fundamental Physics and Middle-Sized Dry Goods

The primacy of physics generates a philosophical problem that the naturalist must solve in order to be entitled to an egalitarian acceptance of the ontological commitments he or she inherits from the special sciences and fundamental physics. The problem is the generalized causal exclusion argument. If there is no genuine causation in the domains of the special sciences but only in fundamental physics then there are grounds for doubting the existence of macroscopic objects and properties, or at least the concreteness of them. The aim of this paper is to show that the causal exclusion problem derives its force from a false dichotomy between Humeanism about causation and a notion of productive or generative causation based on a defunct model of the physical world.

The dominant hurdle to the operation of optomechanical systems in the quantum regime is the coupling of the vibrating element to a thermal reservoir via mechanical supports. Here we propose a scheme that uses an optical spring to replace the mechanical support. We show that the resolved-sideband regime of cooling can be reached in a configuration using a high-reflectivity disk mirror held by an optical tweezer as one of the end mirrors of a Fabry-Perot cavity. We find a final phonon occupation number of the trapped mirror n=0.56 for reasonable parameters, the limit being set by our approximations, and not any fundamental physics. This demonstrates the promise of dielectric disks attached to optical springs for the observation of quantum effects in macroscopic objects.

Generation of quantum correlations between separate objects is of\nsignificance both in fundamental physics and in quantum networks. One important\nchallenge is to create the directional "spooky action-at-a-distanc" effects\nthat Schr\\"{o}dinger called "steering" between two macroscopic and massive\nobjects. Here, we analyze a generic scheme for generating steering correlations\nin cascaded hybrid systems in which two distant oscillators with effective\nmasses of opposite signs are coupled to a unidirectional light field, a setup\nwhich is known to build up quantum correlations by means of quantum back-action\nevasion. The unidirectional coupling of the first to the second oscillator via\nthe light field can be engineered to enhance steering in both directions and\nprovides an active method for controlling the asymmetry of steering. We show\nthat the resulting scheme can efficiently generate unconditional steady-state\nEinstein-Podolsky-Rosen steering between the two subsystems, even in the\npresence of thermal noise and optical losses. As a scenario of particular\ntechnological interest in quantum networks, we use our scheme to engineer\nenhanced steering from an untrusted node with limited tunability (in terms of\ninteraction strength and type with the light field) to a trusted, highly\ntunable node, hence offering a path to implementing one-sided\ndevice-independent quantum tasks.\n

When particles move about randomly in the presence of traps, how long does it take for them to be captured? Well, it depends on the average speed of the particles and the dimensions and distribution of the traps. For example, when neutrons are generated in nuclear fission reactions, they must be captured by other fissionable nuclei in order to sustain a chain reaction. But we learn in introductory physics that these energetic neutrons are traveling at enormous speeds and must be slowed to increase the time that they spend in the vicinity of the nuclei. While the capture of “thermal” particles into lower energy states is an important physical process, it is difficult to simulate macroscopically. For example, where do you get a collection of macroscopic objects that have the means to sustain random motion? Enter Squiggle Balls™—inexpensive spherical cat toys that use a battery-powered motor and asymmetric rotor to roll and tumble happily about.1 Put a few on a bounded, elevated platform with several circular holes, and you have an ideal macroscopic system for exploring the world of capture.

Black holes are unique among astrophysical sources: they are the simplest macroscopic objects in the Universe, and they are extraordinary in terms of their ability to convert energy into electromagnetic and gravitational radiation. Our capacity to probe their nature is limited by the sensitivity of our detectors. The LIGO/Virgo interferometers are the gravitational-wave equivalent of Galileo’s telescope. The first few detections represent the beginning of a long journey of exploration. At the current pace of technological progress, it is reasonable to expect that the gravitational-wave detectors available in the 2035-2050s will be formidable tools to explore these fascinating objects in the cosmos, and space-based detectors with peak sensitivities in the mHz band represent one class of such tools. These detectors have a staggering discovery potential, and they will address fundamental open questions in physics and astronomy. Are astrophysical black holes adequately described by general relativity? Do we have empirical evidence for event horizons? Can black holes provide a glimpse into quantum gravity, or reveal a classical breakdown of Einstein’s gravity? How and when did black holes form, and how do they grow? Are there new long-range interactions or fields in our Universe, potentially related to dark matter and dark energy or a more fundamental description of gravitation? Precision tests of black hole spacetimes with mHz-band gravitational-wave detectors will probe general relativity and fundamental physics in previously inaccessible regimes, and allow us to address some of these fundamental issues in our current understanding of nature.

This chapter presents the fundamental concepts of quantum physics in a form which is intuitive and easily digested. It is intended for readers who are interested in a fun approach for teaching the fundamentals of quantum physics at any level from primary to high school. Quantum physics describes how the universe works on scales from small macroscopic objects down to objects much smaller than atoms. Analogue photons in the form of Nerf gun bullets are used to understand the bulletiness of light. Before exploring the surprising properties of the quantum world, it is very useful to appreciate that photons are sparse and widely separated. Photography with Nerf gun photons can emphasise the particle nature of light. The Nerf gun challenge consists of a set of balloons and an accompanying poster that outlines the physics involved. The photoelectric effect occurs when electrons are ejected from the surface of a metal when irradiated by light of high enough frequency.

Quantum states of mechanical motion can be important resources for quantum information, metrology and studies of fundamental physics. Recent demonstrations of superconducting qubits coupled to acoustic resonators have opened up the possibility of performing quantum operations on macroscale motional modes1-3, which can act as long-lived quantum memories or transducers. In addition, they can potentially be used to test decoherence mechanisms in macroscale objects and other modifications to standard quantum theory4,5. Many of these applications call for the ability to create and characterize complex quantum states, such as states with a well defined phonon number, also known as phonon Fock states. Such capabilities require fast quantum operations and long coherence times of the mechanical mode. Here we demonstrate the controlled generation of multi-phonon Fock states in a macroscale bulk acoustic-wave resonator. We also perform Wigner tomography and state reconstruction to highlight the quantum nature of the prepared states6. These demonstrations are made possible by the long coherence times of our acoustic resonator and our ability to selectively couple a superconducting qubit to individual phonon modes. Our work shows that circuit quantum acoustodynamics7 enables sophisticated quantum control of macroscale mechanical objects and opens up the possibility of using acoustic modes as quantum resources.

We investigated introductory college physics students’ explanations of friction and lubrication through semi‐structured clinical interviews. Although students were able to construct explanations at the atomic scale, they tended to explain phenomena by using attributes of macroscopic objects. For instance, when they described atoms as balls, they tended to associate attributes of real balls to the attributes of the atoms. In the future our results will guide the design of teaching materials to enable students to construct scientifically correct microscopic models of friction and lubrication.

Levitation of macroscopic objects in a vacuum is a key step towards the development of high-precision inertial sensors and pressure sensors, as well as towards the fundamental studies of quantum mechanics and its relation to gravity. Diamagnetic levitation offers a passive method at room temperature to isolate macroscopic objects in vacuum environments, yet eddy current damping remains a critical limitation for electrically conductive materials. We show that there are situations where the motion of conductors in magnetic fields does not, in principle, produce eddy damping, and demonstrate an electrically conducting rotor diamagnetically levitated in an axially symmetric magnetic field in high vacuum. Experimental measurements and finite-element simulations reveal gas collision damping as the dominant loss mechanism at high pressures, while residual eddy damping, which arises from symmetry-breaking factors such as platform tilt or material imperfections, dominates at low pressures. The conclusion is supported by an analytic proof and an analytic example of zero steady current density for a rotating conductor in an axially symmetric magnetic field. This demonstrates a macroscopic levitated rotor with extremely low rotational damping and paves the way to fully suppress rotor damping, enabling ultra-low-loss rotors for gyroscopes, pressure sensing, and fundamental physics tests. Levitation of macroscopic objects in a vacuum is crucial for developing innovative inertial and pressure sensors, as well as exploring the relation between quantum mechanics and gravity. Here, the authors demonstrate a conducting rotor diamagnetically levitated in an axially symmetric magnetic field in high vacuum, with minimal rotational damping.

The conceptual basis of Physics of the Alive is the perception of the fact that any independently functioning living system is simultaneously a macroscopic quantum object and maser (laser of the mm-range) whose pumping out is provided by metabolism due to the mechanism called hierarchy of dissipative strnctures. It is precisely this approach that provides understanding of the macroscopic integrity of organism in accordance with the genetic information (origination due to the coherence of the effective long-range forces) and its diverse differential stability (difference and stability of species and specimens) that is based on the principles of identity and discreteness of quantum mechanics).

Introduction Hilary Putnam explains that: The appeal of materialism lies precisely in this, in its claim to be natural metaphysics within the bounds of science. That a doctrine which promises to gratify our ambition (to know the noumenal) and our caution (not to be unscientific) should have great appeal is hardly something to be wondered at. (Putnam [1983], p. 210) Materialism says that all facts, in particular all mental facts, obtain in virtue of the spatiotemporal distribution, and properties, of matter. It was, as Putnam says, “metaphysics within the bounds of science,” but only so long as science was thought to say that the world is made out of matter. In this century physicists have learned that there is more in the world than matter and, in any case, matter isn't quite what it seemed to be. For this reason many philosophers who think that metaphysics should be informed by science advocate physicalism in place of materialism. Physicalism claims that all facts obtain in virtue of the distribution of the fundamental entities and properties – whatever they turn out to be – of completed fundamental physics . The enterprise of fundamental physics can be characterized (perhaps a little tendentiously) in terms of its ambition and the kinds of concepts it employs in attempting to satisfy that ambition. The goal of physics is, first, to discover the laws that govern or describe the motions of macroscopic material objects; and second, to discover laws that are complete in that they completely account for every event mentioned by those laws.

In this review, I have tried to focus on the development of the field, from\nthe first speculations to the current lines of research. According to\nEinstein's theory of general relativity, black holes are relatively simple\nobjects and completely characterized by their mass, spin angular momentum, and\nelectric charge, but the latter can be ignored in the case of astrophysical\nmacroscopic objects. Search for black holes in the sky started in the early\n1970s with the dynamical measurement of the mass of the compact object in\nCygnus X-1. In the past 10-15 years, astronomers have developed some techniques\nfor measuring the black hole spins. Recently, we have started using\nastrophysical black holes for testing fundamental physics.\n

Optical microcavity: from fundamental physics to functional photonics devices

Manipulating the motion of macroscopic objects near their quantum mechanical uncertainties has been desired in diverse fields, including fundamental physics, sensing, and transducers. Despite progress in ground-state cooling of a levitated solid particle, realizing its nonclassical states has been elusive. Here, we demonstrate quantum squeezing of the motion of a single nanoparticle by rapidly varying its oscillation frequency. We reveal appreciable narrowing of the velocity variance to -4.9 ± 0.1 decibels of that of the ground state using free-expansion measurements. Our work shows that a levitated nanoparticle offers an ideal platform for studying nonclassical states of its motion and provides a route to developing applications in quantum sensing and exploring quantum mechanics at a macroscopic scale.