Time Definition and 1000 Threads

  1. M

    Does Light Decay or Disappear Over Time?

    I vaguelly remember hearing recently that as light travels it decays (or something to that effect).I was wondering if it would be possible to capture a beam of light and have it exist indefinately within a closed structure.I'm curious to hear people's opinions on the matter.Cheers
  2. P

    Will two unequal masses fall to the earth at the same time?

    Free of sufficient impedance, mass moves to meet mass (mass "attracts" mass).Question: If you "drop" two unequal masses (spheres) simultaneously from the same height to the earth, will they meet the earth at the same time? The equality of inertia of either one of these masses is seen in their...
  3. N

    Could a Professor's New Time Travel Idea Actually Work?

    Check this article out:Professor's time travel idea fires up the imagination.It doesn't provide a great amount of detail concering the experiment being proposed. Wether or not it will work or not is not yet known...What are your thoughts on this proposalMorpheus:You have the look of a man who...
  4. L

    Can Time Travel Within the Same Universe Be Possible Through Extra Dimensions?

    I've been thinking about a rather rough theory on a way to time travel within the same universe (to the past). The way I propose to do this is to increase the number of time dimensions of the universe.Begin by imagining time as a 1-dimensional line that can be graphed along a single axis. Due to...
  5. V

    How can I find the car's original speed from its braking distance and time?

    I'm clueless about this problem, I don't know where to start...The driver of a car hits the brakes. The car takes 10 sec to stop and travels 40 meters in that 10 sec. What was the car's original speed?All I know is that I have to find Vo, t = 10 sec, Xo = 0 ... I need a little hint.
  6. J

    Why Does Time Dilation Affect the Astronaut More Than Earth?

    Since a while back, I have had a question bugging my mind. Here it is:If an astronomer in a spaceship leaves earth, travels around at high speed wrt earth, and comes back, time on his spaceship would advance at a slower rate than time on earth.My question: since his motion was relative to...
  7. S

    What are some clever math tricks to save time?

    Do you know any neat math tricks used to save time? Any branch of math.Here is one that i know. I learned it from 'Surely you must be joking Mr. Feynman'For squares near 50.502=2500So if you need 482you use 2500 as your starting point. 100xthe diffrence, which in this case is 2. So...
  8. B

    Can We Travel Faster Than Light and Sound, Defying Time and Space?

    is it possible to go faster than ,as Orson Scott Card would call it, an anssible(messages going anywhere in space in an instant)? if it is than that would mean that if humankind did that, we would actually get somewhere before our image does... scary... how would you like that?does anyone know...
  9. C

    Why Does Pendulum Length Affect Oscillation Time?

    I am 15 years old studing Physics in the UK and i can't understand something!! I under stand using the formula2x(pie)x (spuare root of) lxgi can see that length is a variable BUT why is it. I can't see why the length affects the time of one complete oscilationI know this is probably a really...
  10. C

    How much time does a man have to move before a falling cement block hits him?

    Can anyone help me with this problem:A cement block accidentally falls from rest from the ledge of a 53.0-m-high building. When the block is 14.0 m above the ground, a man, 2.00 m tall, looks up and notices that the block is directly above him. How much time, at most, does the man have to get...
  11. A

    What If Time Is an Ever-Changing Fourth Dimension?

    This is my idea. It's not yet a theory or even a hypothesis; just an idea:What is time? Time is the fourth dimension. I've wondered if the fourth dimension could actually be visualized. I noticed on one of these threads, someone questioned why we haven't seen people from the future in our time...
  12. M

    Is There a Fifth Dimension Beyond Time and Space?

    is their a fifth dimention we know there is four dimentions (strait line,....time)may be there is a fifth one what about:1. (- time) that what we call traveling back by time2. (- subestance) !!3..............ISLAM IS ON THE WAY
  13. U

    Is the Thompson Lamp a Paradox of Change in Time?

    Supposed we have a lamp wich may be on or off....suppose the lamp is off over the interval i = ( t1,t2) and on over j = ( t2,t3)....the problem is whether the lamp is on or off at the instant t2.....
  14. D

    Can Traveling at Light Speed Halt Time for Humans?

    Forgive my ignorance in physics, my school does not offer classes in it so I have to teach myself. Anyway, if a human WAS able to get to C would this put them in a twisted limbo without time? The faster you go the slower time goes, I also remember hearing somewhere that past light speed would be...
  15. B

    Can Absolute Zero Really Halt Time and Entropy?

    If time is, as it has been said, increasing entropy, wouldn't 0 K stop time, 'couse the particles wouldn't be moving (right?) and therefore not increasing entropy?I just don't get it...
  16. D

    How does time affect the relationship between impulse, speed, and acceleration?

    I'm not sure how many times i've done this but I'll do it one more time:N is whatever quality ;t is time;def1: If p=Nt => p is impuls of Ndef2: If N=Vt => V is speed of Ndef3: if N=at2=> a is acceleration of NBut what if N=t?Then Vt=1(meanin how much time passed that much time passed)...
  17. C

    How can both astronauts experience time differently in Relativity?

    I'm sure this, in fact, isn't a paradox. But somebody needs to clear this up for me. I've asked myself this question a lot.Imagine atronaut A and B floating in space with sychronized atomic clocks. First from the point of view of A:Astronaut A observes astonaut B fire his rockets and shoot away...
  18. M

    What is the Complex Structure of Time and Its Role in Events?

    Much topics on this forum are denoted for time. This no wonder since essence of time not known hitherto. Basically participants of the forum are prone to consider the time as the fourth dimention in accompaniment to the three spatial dimentions.However some once vaguely feels insolvency of such...
  19. G

    What Does C^2 Reveal About Time Travel Possibilities?

    From what I can see, no one has ever looked into what C^2 really means and what that means in the context of time or time's force: Momentum or impetus. E=MC^2 is a psychological trick and big mistake. E/M=C^2 is the way this formula should [always] be viewed. I know the two are just reverse...
  20. K

    How Do Time, Length, and Speed Differ in Special Relativity?

    My question is how do you explain the differences in time, length & speed in difference reference frames.I understand that their are factors like a slower clock due to velocity and a length contration but I'm not exactly clear when they apply.could someone give me an example and explain how the...
  21. W

    Do You Need to Use the Speed of Light in Water for Time Dilation Calculations?

    We all know that the speed of light decreases when it goes through mediums such as water. If your trying to, say, figure out the time dilation on a really fast submarine (with the observer also in water), would you need to use the regular speed of light in a vacuum for c in the equation, or...
  22. M

    Is Time a Straight Line, a Circle, or Something Else Entirely?

    Im having trouble with time. Does time move in a straight line (like a string being pulled at a constand rate with a dot in the center, where the dot represents the present), never repeating. Does it move in a circular path repeating constintly at some interval, or does it not even exist? Of...
  23. D

    Can Gravity Influence Our Perception of Time?

    Some time ago I started pondering about the time, trying to parallel it to the other dimensions.Assuming time is no different than any other dimension I believe same rules apply to it as well, for example:(1)Gravity- Earth's gravity forbids you from travelling to the height (unless you find a...
  24. G

    Is Time Travel a Solvable Paradox?

    We've all seen the special effects of time travel in sci-fi movies. Even some top notch physics professors agree time travel could be possible. However we have a few problems to sort out first.http://www.physicspost.com/articles.php?articleId=6admin@physicsforums.comAll New!
  25. P

    How is time dilation determined between two particles in special relativity?

    If one concider one particle moving relative to another, one can calculate that time dilation should occur in one of the particles, ie time moving more slowly than the other.My question is, how do we know which particle one should concider stationary and which is moving. How do one determine...
  26. M

    What is the true definition of time in physics and psychology?

    What is the actual definition of time? How can I say this is Time?Physics or Physicology ?
  27. B

    Does Time Have a Beginning and an End?

    I don't know if this is the right place to ask, but i've been wondering if time had a beginning, and will it have an end?I just don't get it...
  28. L

    Has Light Really Slowed Down Over Time According to Australian Scientists?

    Scientists from Australia say that the light travels through out the space in deferent speeds and it has slowed down through the years are that true?Alexander I have heard a lot about you and I really need your help anyway thanksWhen I look into your eyesThere's nothing there to seeNothing but...
  29. J

    Is Time Truly Undefined or Just a Sequence of Events?

    I think the definition of time is UNDEFINED. Because time is simply a process of CHANGING. There is no way that this process can be explained, because we do not WHY DO THINGS BOTHER TO CHANGE! And if we don't understand why things bother to change, there is no way of giving a definition to...
  30. P

    Is Existence Truly Timeless While Time and Change Are Not?

    Introduction to this issue on this page:
  31. A

    Who is the Greatest Engineer of All Time?

    After seeing the greatest physicist of all time topic i thought i would start a greatest engineer topic. For me it has to be Brunel as he had designed so much stuff like bridges, tunnels and lots of other stuff that are all still being used today in Great Britain.I hope i have put this in the...
  32. M

    Why Can't We Detect Tachyons and Their Impact on Time?

    Why can't we detect tachyons? Don't they cause some sort of disturbance that would alow us to prove their existence? Since they travel faster than c, how would they influence time and how does that influence in particular influence us, insignificant earthlings?MajinVegeta---Sorry, I just...
  33. P

    Is Time Expanding with Space?

    Poll Question:Two factors have recently lead me to believe that - not only is time not infinite - but it is also expanding. Here are the factors:1) Space is expanding, and space cannot exist without time. If you consider all of the spacial dimensions to be expanding together, why wouldn't the...
  34. C

    Is Time Nonexistent for a Photon Traveling at Light Speed?

    According to einstein's relitivity and time dilation if I were on board a ship, the closer I reach the speed of light the more time dilation takes place, so for instance if i were travelling 0.999999999999999999999999999 ... the speed of light (not sure how many 9's), I could on board my ship...
  35. P

    Does Time Really Stop for Objects at Zero Velocity?

    When an object is at complete rest (it has no velocity), its time continues; its time does NOT stop.Over the past week or so I have been deriving this proof, and I am at a completion. Awhile ago some of us were arguing over whether time stops, or freezes, for an object at complete zero velocity...
  36. P

    Is Time a Dimension or a Complex Structure?

    Poll Question:All right, I'm sick of this contraversy between different views of what "time" is. It seems to me that time is a dimension (or, specifically, "coordinate"). Some people seem to think otherwise. As I can't quite understand their views, and I don't want to mis-quote someone, I will...
  37. P

    Is Time Perception Different for 2D Creatures?

    Is "time" dependant upon dimensions? Say, is a 2D creature's perception of time the same, slower, or faster than ours??-CaseyI Shave With Occam's Razor.
  38. S

    Why is my train travel time calculation different from the textbook answer?

    i got this question from a physics book (Serway's Physics for scientist and engineer), it is easy, but for some reason the answer that i am getting is not the same as the answer of the book (although i remmember solving it before, and getting the same answer !)here is the question :" a train...
  39. W

    How Does a Computer Keep Time When Unplugged?

    A while ago , I booted up my old computer which as hasn't been turned on or plugged in for quite awhile, and I noticed that the timer at the bottom right corner of the screen still had the right time! I don't see how the computer kept track of time even tho it was unplugged. Unlike a clock ...
  40. D

    Is it time to rethink British identity vs. English identity?

    Is niggles a word? Oh well if it wasn't it is now. I just I'd thought share a little annoyance with you all: I hate being generalised as British....I'm English! Does this annoy any others of you folk with whom I share this delightful island?
  41. L

    Does youth really see more time, or is it just a perception?

    I have often wondered whether this (the title) was true.We all remember our youth as seeming to last forever; and then when we get to about 16/18 (ish), the years seem to fly by... progressively faster.Is this totally psychological, or do you think that there may be some intrinsic 'law' involved...
  42. R

    Is Time Travel Limited by Observer Constraints?

    To the future? when I open my eyes I allways find myself right back where I started...the present!No matter how hard I try, I cannot get back to just before I thought of the 'thought experiment'..say ten minutes ago?Is this because of the constraints of observer limits or Time limits?Come to...
  43. D

    Analysis of HannonRJ''s time dilation paper

    Seeing as HannonRJ has posted his time dilation paper for us to view along with his redshift paper, here are my comments. You can read the original paper athttp://www.71010.net/TDUP1.htmNote that I have rewritten a couple of the equations so they show up here.quote:From the paper:The Greenberg...
  44. S

    Is Teleportation and Time Travel Really Possible Given the Laws of Physics?

    I'm sure someone else has thought of this before, But while myself and an assistant were researching the metaphysics of mental teleportation and time travel (which seems to hold more creedence, as the research performed by the CIA in 1972 to 1992, and the lab at Princeton for the past 12 years)-...
  45. L

    Why do time measurements differ for a traveler moving at near-light speed?

    Let's imagine a man traveling from earth to a planet X at a speed close to that of light. Let's also imagine that the man has a telescope powerful enough to track the movements of earth's rotation.As the man travels towards planet X, light emited from Earth takes longer in between light rays to...
  46. N

    How do you calculate the time a projectile spends in the air at an angle?

    I have a problem and I'm not sure if I did it correctly, and it involves kinematics. If a projectile is fired at a 20 degree angle with a velocity of 15 m/s (ignoring air resistance), from a height of 1.5 m, how much time does it spend in the air?I've drawn up a diagram...
  47. S

    How can Bernoulli's principle help solve a pump's flow time for 20 liters?

    A pump (2*10.000 Pa) has to carry 20 liter through a 10 meters long pipe into a 10m high bucket.A(pipe) = 0,05m� = const.........................==== <---------- 10...
  48. F

    What is gravitational time dilation and how does it affect perceptions of time?

    I would like to know more about gravitational time dilation. My understanding of it may be incorrect so please let me know!My understanding:Person in an accelerating reference frame / frame in gravitational field will "see" time as speeded up in a frame that is stationary or moving w/ constant...
  49. E

    Is Time Travel to the Future Really Possible?

    I was thinking about time travel today!. And i noticed that most all time travel theories are for travel into the past well, Would it be possible to travel into the future? But!, what if there is no future yet? Although that is rather unlikely.. or is it. Also is there a possibility of maybe...
  50. C

    Is Time Just a Word in a Multi-Dimensional Universe?

    Someone just knocked the dense dirt out of my head about something that is, to me, so stunningly obvious, I can't believe how easy it is to allow a few words and concepts murder and obliterate the power of perception. Not mere logical piffle-poffle...my logic so entwined with what I've let...
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