Time Observables in a Timeless Universe

Time in quantum mechanics is peculiar: it is an observable that cannot be associated to an Hermitian operator. As a consequence it is impossible to explain dynamics in an isolated system without invoking an external classical clock, a fact that becomes particularly problematic in the context of quantum gravity. An unconventional solution was pioneered by Page and Wootters (PaW) in 1983. PaW showed that dynamics can be an emergent property of the entanglement between two subsystems of a static Universe. In this work we first investigate the possibility to introduce in this framework a Hermitian time operator complement of a clock Hamiltonian having an equally-spaced energy spectrum. An Hermitian operator complement of such Hamiltonian was introduced by Pegg in 1998, who named it "Age". We show here that Age, when introduced in the PaW context, can be interpreted as a proper Hermitian time operator conjugate to a "good" clock Hamiltonian. We therefore show that, still following Pegg's formalism, it is possible to introduce in the PaW framework bounded clock Hamiltonians with an unequally-spaced energy spectrum with rational energy ratios. In this case time is described by a POVM and we demonstrate that Pegg's POVM states provide a consistent dynamical evolution of the system even if they are not orthogonal, and therefore partially undistinguishables.

Conditional interpretation of time in quantum gravity and a time operator in relativistic quantum mechanics

The problem of time in the quantization of gravity arises from the fact that time in Schrödinger’s equation is a parameter. This sets time apart from the spatial coordinates, represented by operators in quantum mechanics (QM). Thus “time” in QM and “time” in general relativity (GR) are seen as mutually incompatible notions. The introduction of a dynamical time operator in relativistic quantum mechanics (RQM), that follows from the canonical quantization of special relativity and that in the Heisenberg picture is also a function of the parameter [Formula: see text] (identified as the laboratory time), prompts to examine whether it can help to solve the disfunction referred to above. In particular, its application to the conditional interpretation of time in the canonical quantization approach to quantum gravity is developed.

Rancang Bangun Sistem Kendali pada Robot Tempur Menggunakan Joystick Berbasis Arduino

Perkembangan teknologi saat ini sangatlah pesat dengan banyaknya pembuatan robot yang dimanfaatkan dalam kehidupan sehari-hari. Saat ini, bahkan robot digunakan dalam sebuah pasukan militer yang bertujuan untuk membantu dalam tugas operasi. Robot tempur merupakan suatu alat penggabungan mekanik dan elektronika yang dirancang untuk bergerak dari suatu tempat ke tempat lain serta dilengkapi senjata yang dapat menembak musuh secara real time. Operator menggunakan sebuah joystick untuk mengendalikan robot tempur. Penelitian ini membahas tentang perancangan sebuah kontrol joystick untuk mengendalikan robot tempur secara jarak jauh. Metode yang digunakan adalah metode eksperimen, penelitian ini terfokus antara komunikasi Joystick dengan robot melalui koneksi modul NRF24L01 sehingga gerakan robot akan bergerak sesuai dengan gerakan Joystick yang telah diprogram. Hasil dari penelitian menunjukkan bahwa robot dapat kendalikan dengan mudah menggunakan Joystick dan secara real time terlihat pada layar Android yang terpasang pada kontrol Joystick. Penelitian ini sangat mendukung tugas operasi personil TNI dalam menjalankan misinya dengan memanfaatkan robot tempur.

Time Operator, Real Tunneling Time in Strong Field Interaction and the Attoclock

Attosecond science, beyond its importance from application point of view, is of a fundamental interest in physics. The measurement of tunneling time in attosecond experiments offers a fruitful opportunity to understand the role of time in quantum mechanics. In the present work, we show that our real T-time relation derived in earlier works can be derived from an observable or a time operator, which obeys an ordinary commutation relation. Moreover, we show that our real T-time can also be constructed, inter alia, from the well-known Aharonov–Bohm time operator. This shows that the specific form of the time operator is not decisive, and dynamical time operators relate identically to the intrinsic time of the system. It contrasts the famous Pauli theorem, and confirms the fact that time is an observable, i.e., the existence of time operator and that the time is not a parameter in quantum mechanics. Furthermore, we discuss the relations with different types of tunneling times, such as Eisenbud–Wigner time, dwell time, and the statistically or probabilistic defined tunneling time. We conclude with the hotly debated interpretation of the attoclock measurement and the advantage of the real T-time picture versus the imaginary one.

Ultrasonic Sensor-Based Automated Water Dam Shutter

Monitoring the level of water in dams is necessary to ensure optimal operation and safety. Water level monitoring is normally done manually by a full-time operator. This results mostly in a waste of water due to the inability of the operator to accurately determine the quantity of water to release from the dam gate. The aim of this paper is to present the design of a system to automatically open and close dam gates based on the level of water in the dam. The system is based on a low-cost microcontroller and an ultrasonic sensor to read water level in the dam. SMS messages are sent to nearby residents to warn them of the opening of the dam gate. An alarm is also sounds before the eventual opening of the dam gate.