How many G's would you experience going speed of light?

shadow735 · Dec 28, 2007

If the Speed of light is 186,000 miles per second and 669,600,000 MPH, if you could travel the speed of light how many G's would you experience? <div class="Discussion_UserSignature"> </div>

MeteorWayne · Dec 28, 2007

The force you feel is based on accleration. If you are traveling at the speed of light (which is impossible) you would feel 0 G's because you could not go any faster (accelerate). <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

bearack · Dec 28, 2007

Plus, would there have to be gravity in order to encounter G force? <div class="Discussion_UserSignature"> <img id="06322a8d-f18d-4ab1-8ea7-150275a4cb53" src="http://sitelife.space.com/ver1.0/Content/images/store/6/14/06322a8d-f18d-4ab1-8ea7-150275a4cb53.Large.jpg" alt="blog post photo" /> </div>

MeteorWayne · Dec 28, 2007

No, gravity is acceleration. That's the whole point of relativity. There's no way to differentiate between acceleration from thrust, or gravity, if you don't know the source. All that counts is that your mass follows F=ma. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

shadow735 · Dec 28, 2007

If you could travel the speed of light, what type of G forces would you encounter as you accelerated to the speed of light? and on the opposite spectrum if you were at a complete stop and instantly accelerated to the speed of light what would the G forces be for the moment of acceleration? I just can understand how there cannot be g forces when you are going fast. Wouldnt you be pushed back against your seat? <div class="Discussion_UserSignature"> </div>

MeteorWayne · Dec 28, 2007

No you would not. If there is no change in your speed or direction, there are no G forces; i.e. there is no acceleration. You are pushed back in your seat in an airliner when it accelerates from zero to takeoff speed. Once you are cruising at 35,000 feet, you can walk about just fine, since there is no change in your speed or velocity, hence no acceleration. All that exists is the gravity of the earth's mass, which hold you to the floor. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

yevaud · Dec 28, 2007

You could accelerate to within a fraction of "C," comfortably, at one G. In point of fact, one can achieve 0.9 of C in 520 (+/-) days at 9.8 M/S^2. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

shadow735 · Dec 28, 2007

one can achieve 0.9 of C in 520 (+/-) days at 9.8 M/S^2. Can you Dumb that down for me, im not quite understanding what that means <div class="Discussion_UserSignature"> </div>

yevaud · Dec 28, 2007

Yes. By continually accelerating at what would seem to you (as a passenger on a ship) to be one Earth gravity, at 520 (+/-) days on, you would have achieved 90% of the Speed Of Light. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

adrenalynn · Dec 28, 2007

... And you would experience no more "g-force" than you would standing still on earth. (just wanted to clarify that). 1G is the equivalent of the force you feel standing on earth from the inherent force of gravity. So the entire 520 days you would experience what would feel to you as no force at all. Of course, there would be acceleration in excess of that 1G to escape earth. But once you were in space and accelerating at 1G, it'd be the same as standing on the planet. In fact, you could acheive .9C and experience NEGATIVE g-forces in much the same way - with continual acceleration of less than one G. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

SpeedFreek · Dec 29, 2007

You cannot accelerate to the speed of light, but if you had the energy and the protection required you might get somewhere close. The amount of G's you experience depends on your acceleration. The amount force with which you accelerate is limited by your propulsion method and the duration of your acceleration is limited by your fuel capacity. Theoretically, if you were able to carry enough fuel to accelerate with a force of 1 gravity for around 520 days, you would reach 90% of the speed of light. But there are a few problems we need to overcome first. At those kinds of relativistic speeds there is nothing known to science that could protect the ship from floating debris or dust. Anything you hit at that speed will cause a big hole in any ships hull. Also, interstellar gas or cosmic rays become deadly if you pass through them at relativistic speeds - hard radiation would be streaming through your ship. If you could overcome those problems there is the fuel issue. While it might be true that accelerating at 1g for around 520 days should get you to 90% of the speed of light, there is the problem of your relativistic mass. As you accelerate, your relativistic mass increases, which means you require more energy to continue accelerating with the same force. This increase in relativistic mass isn't apparent at the speeds we are used to on Earth, it only becomes an issue once you have reached a decent proportion of the speed of light. For instance, at around 86% of light speed, your relativistic mass is doubled, so it would take you twice the thrust (and fuel) to keep up a 1g acceleration at that speed than it did at the start of your journey. At 99% of light speed, your relativistic mass is 7 times larger than it was at the beginning of your journey, and at 99.99% of the speed of light your mass has apparently increased by over 70 times! This is why it is impossible to accelerate to the speed of li <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

weeman · Dec 31, 2007

If you could travel the speed of light, what type of G forces would you encounter as you accelerated to the speed of light? and on the opposite spectrum if you were at a complete stop and instantly accelerated to the speed of light what would the G forces be for the moment of acceleration? Meteorwayne is correct, once you hit lightspeed, and no longer accelerating, you would not feel any G's. You can experience this while driving a car. When you speed up the on-ramp of the freeway, you feel the G's pushing back on you since you're traveling from 0-65mph in a short period of time. However, once you hit 65mph, and you sustain that speed, you will no longer feel the G's pushing against you. Keep in mind too that G's have different affects on the body depending on how long we experience them for. A hard hit between two football players may very well measure over 100 G's, but it lasts for only a few milliseconds, so they are able to walk away from the hit. The two players might be rattled by the hard hit, but more than likely, neither of them would guess that they just clashed at a force that is far greater than what the astronauts experience upon liftoff! When a racecar driver speeds around a tight turn, he may experience only 3-4 G's, but he feels the affects more than the two football players because he may experience it for several seconds. If you were to experience the same G's as the football players over a long period of time, say 10 seconds, you would not be in good shape. Drivers of top fuel dragsters have blacked out by the time they reach the end of the quarter mile, all because of the G forces they experience. They only experience about 5 G's, but it's sustained over a period of about 4-5 seconds, which takes a toll on the human body. The 5 G's that top fuel racers can experience is far, far less than the intense G's that are present in the t <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

adrenalynn · Dec 31, 2007

I have actually been bruised head to toe, literally, after an endurance car race. The forces, pressure, counter forces, heat, vibration all combine to make a very nasty environment. Anyone that says "auto racing isn't a real sport" is invited to come take a few hot laps with me - full nomex required (but rentable). <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

SpeedFreek · Dec 31, 2007

and on the opposite spectrum if you were at a complete stop and instantly accelerated to the speed of light what would the G forces be for the moment of acceleration? Well, we have explained that we cannot accelerate to the speed of light itself, due to the infinite energy that would be required to do so. Also, as was said above, if you are travelling at a constant speed (not accelerating) you feel no G force. The human body can withstand a 1g acceleration easily (we are experiencing 1g all the time!), but cannot withstand 3-4 g for more than a few seconds without an anti-g suit. Pilots of supersonic jet fighters can withstand higher prolonged G forces, but the duration would still only be measured in seconds and the force would be less than 10 g. Now let's consider what G force you would feel if you instantly accelerated to the speed of light. How long is an instant? To me, that is no time at all, an instant change from one speed to another. In that case, you would be accelerating by an infinite amount and thus would feel infinite G force! I just cant understand how there cannot be g forces when you are going fast. Wouldnt you be pushed back against your seat? You don't feel a thing once you are going fast. You aren't pressed back in your seat in the car when you are cruising at a constant 100 mph. You are only pressed back in your seat whilst you accelerate to 100 mph. You feel pulled forwards out of your seat as you decelerate. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

SpeedFreek · Dec 31, 2007

...full nomex required (but rentable). Does the rental include the cleaning bill? <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

nexium · Dec 31, 2007

This is a bit like asking what you get when you divide by zero. At 1/10th the speed of light you are in free fall inside your spacecraft = approximately zero gravity. Same thing at some what higher speed. You produce artifical gravity when you speed up or slow down: too much artificial gravity if you try to change speed or direction rapidly. Neil

vandivx · Jan 1, 2008

seems like the 'shadow' is totally lost as he stopped responding, I am afraid speedfreek's explanations are way outside the OP abilities I was surprised the other day that my brother didn't know that objects gravitate to themselves as well as to Earth, grown up people can have surprising lack of physical knowledge for sure I think nobody pointed out that the g forces one would encounter while accelerating to any speed depend on how much one is accelerating, it is possible to achieve very high speeds with very little acceleration and therefore very little g forces if one is willing to accelerate long time, on the other hand instant acceleration is unphysical and one should be warned of that error very strongly same as mom slaps her child when it tries to touch hot stove top LOL speedfreeks explanation <blockquote>In reply to:<hr />"How long is an instant? To me, that is no time at all, an instant change from one speed to another. In that case, you would be accelerating by an infinite amount and thus would feel infinite G force!"<hr /></blockquote> is not the way to explain it, all you get is the guy is going to ask next how many Gs is 'infinite G' force, it is totally misleading because people take infinite not as something unphysical (that's like talking about square circle) but simply some very great amount vanDivX <div class="Discussion_UserSignature"> </div>

adrenalynn · Jan 1, 2008

I think nobody pointed out that the g forces one would encounter while accelerating to any speed depend on how much one is accelerating, it is possible to achieve very high speeds with very little acceleration and therefore very little g forces if one is willing to accelerate long time Nearly everyone in the thread did, yes. Multiple times. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

2844az · Jan 1, 2008

That was a very interesting question on G-force and light speed. It is amazing how electro-magnetic radiation endures the speed of light. This question reminds me of Hawkinsâ€™s Paradox. One you get to the Event Horizon and you are sucked down into a black hole (perhaps faster than the speed of light). I wonder what the instant G-force would be. Supposing you would be ripped apart on the molecular and atomic level. Your quarks might be thrown from Event Horizon to infinity. Good question. Gary.

billslugg · Jan 1, 2008

Actually, when you are falling through a gravitational field, as falling into a black hole, you will feel no g-force at all. Additionally, given a sufficiently massive black hole, the tidal forces at the event horizon would not pull you apart. <div class="Discussion_UserSignature"> </div>

2844az · Jan 1, 2008

I was trying to understand what you were saying Bill. I was thinking that Hawkinsâ€™s theory of going into a Black hole was: that you would be vaporized by the high thermal temperature and sucked into eventually nothingness. I guess if you were vaporized first, then G-force would not be an issue. I think Susskindâ€™s theory was that you would be sucked in an smeared on the walls of a Black hole into a 2 dimensional form and spread out. Thus retaining information. If that were the case then G-force would not be an issue either. Either way it is not good. Gary

yevaud · Jan 1, 2008

*Ahem* Hawking <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

SpeedFreek · Jan 1, 2008

<blockquote>In reply to:<hr />seems like the 'shadow' is totally lost as he stopped responding, I am afraid speedfreek's explanations are way outside the OP abilities<hr /></blockquote> You may be right, but judging by the use of language in the OPs posts I thought they could handle it! These are difficult concepts to explain at the best of times. <blockquote>In reply to:<hr />is not the way to explain it, all you get is the guy is going to ask next how many Gs is 'infinite G' force, it is totally misleading because people take infinite not as something unphysical (that's like talking about square circle) but simply some very great amount<hr /></blockquote> Again, you may be right, but for me it is difficult to explain it any other way. The specific question was "if you were at a complete stop and instantly accelerated to the speed of light what would the G forces be for the moment of acceleration?" and I can only answer that the G forces would be infinite, under those conditions. I suppose I should have said you cannot accelerate instantly, because of this. Sometimes I take it as a given that when infinity pops out of the equations that means you are asking the impossible and I forget to explain that fully. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

billslugg · Jan 1, 2008

you would be vaporized by the high thermal temperature Well, sort of. IF there was a bunch of gas in the vicinity, and the particles did not happen to have been precisely aimed at the black hole, then the gas will go in orbit around it. In doing so, gas particles at different distances from the BH will be traveling at different speeds, thus "shear" will occur. Shear means turbulence which means heat. And in the case of a black hole that heat is up in the X-ray region. This would not be a good place to be around. BUT in the case of a naked singularity, that is a black hole with no in falling matter, there would be no X-rays or anything else. Now, look up "tidal forces at event horizon". You will find that the pull of gravity falls off from a black hole by the inverse square. You will also find that tidal forces (delta G over a small distance) falls off with the square of distance. For a sufficiently massive black hole, the horizon where light cannot escape is far enough out from the black hole that the delta G is small enough that it IS survivable by a human! In other words, for a large enough, bare enough, black hole you could fall into it and be able to see what was going on! PS - I don't know anything about Susskind. <div class="Discussion_UserSignature"> </div>

vandivx · Jan 2, 2008

well yes, but not in a way that the thread starter would understand, he made it plenty clear that he has severe problems with most basic facts of physics for example nexium just above my post did point it out but not in a way the guy could grasp IMO <blockquote>In reply to:<hr />nexium: You produce artifical gravity when you speed up or slow down: too much artificial gravity if you try to change speed or direction rapidly.<hr /></blockquote> I bet you anything he wouldn't get the message when it is put like this, how's he going to grasp 'artifical gravity' when he doesn't know the most basic thing about the whole subject known since Galileo times (in explicit terms at least) speedfreek is excellent example of somebody too brilliant who couldn't teach basic physics to interested laymen going by his lengthy albeit correct posts as far as physics go, his post covers it all but smother the lay readers in way too much information, remainds me of late Feynman when he got heated up in his enthusiasm for physics and lost his class (have to listen to recorded lectures, it doesn't show much in transcripted books) on the other hand most threads typically turn into experts talking to other experts with orig posters only providing the first impetus which is ok with me too, just thought to point it out vanDivX <div class="Discussion_UserSignature"> </div>

How many G's would you experience going speed of light?

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