1. Quantum Alchemy

    B A Question about space and the multiverse

    My question is about space and the multiverse. I was reading work by Max Tegmark and he sees the multiverse as Level 1-4. A Level 1 multiverse seems like it's self evident and I was wondering about the evidence against it. It's simple: Space expands faster than we can observe it so we exist in...
  2. S

    A Is there any theory that can be modeled in any type of space?

    Is there any theory in physics that can be modelled in any type of space (Hilbert space, Euclidean, Non-Euclidean...etc)? And if yes, could that theory also contain/be compatible with all types of (physical) symmetries?
  3. J

    B How physics equations transform under inverse of parameters

    It is obvious that there is a one-to-one relationship between real numbers (defined to include infinity) and their multiplicative inverses (assuming we map the inverse of zero to infinity and vice versa). Thus, one should be able to replace the distance between two points in space with it's...
  4. G

    I Understanding forced motion in space

    Hello, Can you please explain the analogy oft quoted to explain the concept of applied motion to objects in space, which goes as follows : 1. You are standing on a skateboard or sitting in a boat floating on the water, holding a bowling ball. 2. You throw the bowling ball towards the back of...
  5. Ryu

    Theoretical Higher spatial dimensions question

    So I had a topic which I would like to fact check from an informed scientific source. Basically there is an argument about whether or not an object that naturally exists in a fourth dimensional space, would by default have more than countably infinite times the energy of a 3 dimensional Object...
  6. H

    A peculiar world

    Hello everyone! I am an undergraduate getting three bachelors in Anthropology/Ecology/Neurosciences (just to show off of course), but sadly no true physics (I don't show off that much, I'm still humble). I am working on a personal project, a tabletop role playing game, where my main struggle is...
  7. JD_PM

    Physics Essential skills for applying for Space Agency jobs as a physicist

    Hi Physics Forums community. Let me briefly explain my current state of affairs. Next season, if every goes as planned, I will begin my Master's in Physics. I have, what I call, a positive problem; I like lots of branches of Physics (I study Physics because of pure passion and not because I...
  8. Antony Death

    B Is the current definition of gravity accurate?

    The current definition of Gravity is: The force of attraction between bodies as a result of their mass. Gravity affects both the space and time of the area surrounding a mass, diminishing with distance, so is the current accepted definition truly accurate? Do I have the correct definition and if...
  9. A

    Flight Path Angle and Velocity During Atmospheric Re-entry

    A space vehicle enters the sensible atmosphere of the earth (300,000 ft) with a velocity of 25,000 ft/sec at a flight-path angle of -60 degrees. What is its velocity and flight-path angle at an altitude of 100 nautical miles during descent? (Assuming no drag or perturbations, two body orbital...
  10. Mr C Odd

    Time dilation in a magnetic field

    Hi all. I was wondering if time is dilated whilst travelling in a stable magnetic field that is generated by the object travelling, and if so, does this vary if you reduce or intensify the magnetic field? Also, what happens if the object is generating two opposing magnetic fields, would...
  11. H

    B Feasibility of a L1 Gravity Swing Cold Launch?

    At an L1 LaGrangian point between two bodies, one could - materials science notwithstanding - pit two of Newton's Laws (LM3,UG) against each other to provide thruster-free stationkeeping. Would it be feasible to use that to launch free from the system ? either spit out like a watermelon seed...
  12. V

    B Is space is continuous or discrete?

    I was watching a video where well known physicist Lisa Randall said that we still don't know whether space is continuous or discrete. My question is, how do we find whether space is continuous or discrete?? What type of experiments are possible? Is it being done now?? I am thinking this may be...
  13. M

    What would happen to a blob of mercury in space?

    How long would it take for a blob of mercury (the size of a marble or so) to freeze in space? I'd emagine it would have to boil in some way first, and that would send pieces of it flying around, but the surface tension of mercury is much greater than that of water, or urine (as we'd seen...
  14. S

    B How do we know that light that comes from the stars is in past?

    So for some reason, from time to time, i always come back to this question and i can't remember that part of the physics while i was studying and most of the explanation are pretty generic. Basically how do we know that light actually travels and not just oscillate and transfer energy when...
  15. T

    I How can I go about making a "Space Proof" coating?

    So im planning on launching a Satellite to promote the Dogecoin cryptocurrency. One of the main points is printing/painting (Or whatever) the logo on the side of a metal panel. How can I make it so it doesn't melt off or turn white from radiation so quickly?
  16. N

    I If you threw a warm water balloon into space, would it boil?

    And by how much would the balloon expand, if at all?
  17. R

    I Question about time and space

    if the earth were set between 2 Sun (our sun) in the distance which the time passes the exact same as it is right now, does the distance between us and each sun would be the same as it is right now?
  18. pairofstrings

    I Mathematical Structure and Mathematical Space Hierarchies

    Hi. I am trying to understand the images that I have posted below. Each layer of Mathematical Structure Hierarchy in the image in this post and Mathematical Space Hierarchy in the image in this post are: statements. 1. What do these statements of each layer of these hierarchies in the...
  19. R

    Materials for space applications?

    So I'm working on this project for a inflatable solar sail (so a spherical solar sail) and we are really only verifying the deployment of the sail in space (from a cubesat)....We are doing a mock PDR and I need to find info on the sail we'll be using. My job is to find an "off the shelf"...
  20. Kenneth Boon Faker

    B What does the 'space' inside an atom consist of?

    Atoms make up all the material stuff around us, but most of an atom is empty space. The nucleus at the centre of an atom (99.95 percent of its mass) is orbited by tiny electrons (only 0.05 percent or less of the overall atomic mass). And as you've probably heard, an analogy is to think of the...
  21. Craftek_Ana

    B Traveling to Mars and time dilation

    If/when we go to Mars how will we deal with time dilation due to the gravitational differences between the two planets?
  22. mjda

    Resolving bodies at large distances

    1. Homework Statement If a 6.5m diameter telescope operates at wavelengths between 600nm to 2800nm, and for stellar densities similar to the Solar neighbourhood, what is the range of distances this telescope can resolve individual stars? 2. Homework Equations 3. The Attempt at a Solution...
  23. R

    I Why does bent space set objects in motion?

    Two stationary masses will attract each other. That is, they start moving towards each other. For example, a stationary apple will fall to earth. I can see bent space affecting the trajectory of a moving object. ...but how does bent space explain that stationary objects start moving?
  24. David Dodson

    I Does space have its own density?

    Does space have its own density? i.e. a mass density distinct from the mass density of 'particles' in it? or may it have a uniform density of some kind of vast particle(s)? If so, would the effect on observable masses largely cancel out? One answer from...
  25. T

    Help with an Apollo space program flight simulation guide

    Hi all, This is my first time posting on this forum. I'm not sure if this is the right place to ask this question so apologies in advance. Perhaps someone could recommend a more appropriate forum for me to post this on. I'm working on creating documentation for a simulation. It's an Apollo...
  26. A

    I Changing the ISS's orbital inclination to match the Moon

    What is the practical feasibility of changing the International Space Station's orbital inclination to match the orbit of the Moon? Major future missions beyond the Earth-Moon system (ie: space colonization) will likely require in-orbit assembly of components from multiple launches. And...
  27. P

    I Is it possible to use the vacuum to launch a rocket?

    Hey I'm new to Physics. I have a question. Is it possible to use the force generated when air entera a vacuum tube to launch something into space? Can anybody throw some light on this in simple words please. Thank You.
  28. pixelperfect

    I If Dark Matter and Dark Energy exist, what produces them?

    My query is really to find out what everybody thinks about 'empty space'. Does dark matter/energy exist and if so, it fills all voids in the universe? Where does it come from? Is it produced by some force? Without DM/DE, does space even exist? Say the supernovas, the collision of neutron stars...
  29. Rednecknav

    I Space Trash

    How much energy needs to be be expended to throw a non operating satellite (or other space trash) out of orbit (L4 or L5) or L2 into deeper space.... thus minimizing space debris in earth orbit. I could only find formulas for getting an object INTO orbit.... Background of question: we were...
  30. S

    How to calculate ambient temperature in space or in orbit?

    How would I go about calculating the ambient temperature in low earth orbit (LEO) at approximately 400 km? What equations should I be referencing to determine the temperature of sun light side and/or eclipse side? Thanks!