What is the correct derivation of the relativistic rocket equation? One participant describes two methods for deriving the relativistic rocket equation, noting discrepancies in the results due to a sign difference in the equations Another participant suggests that the mass should decrease by energy divided by c² rather than by the mass ejected, citing the case of an ideal photon drive as an example
Photon in a mirrored box moving in direction of travel The discussion revolves around the behavior of a photon inside a hypothetical box made of inward-facing mirrors, focusing on how its properties are perceived by observers at rest with the box compared to those moving parallel to the photon's direction of travel The scope includes concepts from special relativity, Doppler effects, and the nature of light, with participants exploring both
Photon-Foil FTL Drive theory - Physics Forums The discussion revolves around a theoretical faster-than-light (FTL) drive system based on the concept of "photon foils," as proposed by a participant developing ideas for a sci-fi novel The scope includes speculative physics, theoretical models of astrophysics, and narrative techniques in science fiction writing Participants generally disagree on the balance between technical detail and
Harnessing the Power of Photons: A Closer Look at Photon Space . . . The discussion centers on the feasibility of using photons for spacecraft propulsion, exploring theoretical calculations and practical implications Participants examine energy requirements, propulsion efficiency, and the challenges associated with photon-based propulsion systems Exploratory Technical explanation Debate contested Mathematical reasoning One participant presents calculations
Can you explain the phenomenon of stimulated emission in lasers? Concerns are raised regarding the conservation of momentum in the context of stimulated emission, with one participant noting a lack of clarity on how momentum transfer occurs without a change in energy, frequency, or phase of the incident photon
Continuous-variable cat state - phonon number mean and variance SUMMARY The discussion centers on the mean and variance of photon number in continuous-variable cat states, specifically the expressions $ n =|\alpha {|}^{2}\mathrm{tanh}({\alpha }^{2})$ and $ {n}^{2} =|\alpha {|}^{2}({\alpha }^{2}\textcolor[rgb]{1,0,0}{\text{sech}}({\alpha }^{2}{)}^{2}+\mathrm{tanh}({\alpha }^{2}))$ Several references are provided to validate these expressions, including B
Create Photonic Force with Flashlight? - Physics Forums It's a very low power example of a "photon drive", a rocket where the exhaust is photons The frequency of the photons in a photon drive does not matter - the momentum in the exhaust P is the energy of the exhaust E divided by the speed of light p = E c irregardless of the frequency of the photons
How is efficiency defined in rocket propulsion? - Physics Forums The discussion revolves around the definition of efficiency in rocket propulsion, particularly in the context of different propulsion methods, including photon drives and traditional chemical rockets Participants explore the implications of internal forces, momentum, and energy density in relation to thrust generation and efficiency metrics Participants express multiple competing views on
Sending drive Pulse in CQED and visualize the state by QuTip It is possible to have QND measurements of photon number and its parity without learning the value of the photon number where is a time-dependent drive term In order for the qubit to be dependent on the number of photons in the cavity, the cavity dissipation should needs to be much smaller than the corrections of the qubit resonance frequency
Can light generate propulsion? - Physics Forums A photon drive is in the sweet spot for an antimatter fuel source With less energy density than that, a lower exhaust velocity is better -- eject the expended fuel as reaction mass