• Log InLog In
  • Register
Liquid`
Team Liquid Liquipedia
EDT 17:49
CEST 23:49
KST 06:49
  • Home
  • Forum
  • Calendar
  • Streams
  • Liquipedia
  • Features
  • Store
  • EPT
  • TL+
  • StarCraft 2
  • Brood War
  • Smash
  • Heroes
  • Counter-Strike
  • Overwatch
  • Liquibet
  • Fantasy StarCraft
  • TLPD
  • StarCraft 2
  • Brood War
  • Blogs
Forum Sidebar
Events/Features
News
Featured News
Team Liquid Map Contest #22 - The Finalists12[ASL21] Ro16 Preview Pt1: Fresh Flow9[ASL21] Ro24 Preview Pt2: News Flash10[ASL21] Ro24 Preview Pt1: New Chaos0Team Liquid Map Contest #22 - Presented by Monster Energy21
Community News
2026 GSL Season 1 Qualifiers11Maestros of the Game 2 announced32026 GSL Tour plans announced10Weekly Cups (April 6-12): herO doubles, "Villains" prevail1MaNa leaves Team Liquid20
StarCraft 2
General
Weekly Cups (April 6-12): herO doubles, "Villains" prevail MaNa leaves Team Liquid Oliveira Would Have Returned If EWC Continued Team Liquid Map Contest #22 - The Finalists 2026 GSL Tour plans announced
Tourneys
2026 GSL Season 1 Qualifiers Sparkling Tuna Cup - Weekly Open Tournament Master Swan Open (Global Bronze-Master 2) SEL Doubles (SC Evo Bimonthly) $5,000 WardiTV TLMC tournament - Presented by Monster Energy
Strategy
Custom Maps
[D]RTS in all its shapes and glory <3 [A] Nemrods 1/4 players [M] (2) Frigid Storage
External Content
Mutation # 521 Memorable Boss The PondCast: SC2 News & Results Mutation # 520 Moving Fees Mutation # 519 Inner Power
Brood War
General
BW General Discussion Pros React To: Tulbo in Ro.16 Group A ASL21 General Discussion [BSL22] RO32 Group Stage mca64Launcher - New Version with StarCraft: Remast
Tourneys
[BSL22] RO32 Group D - Sunday 21:00 CEST [BSL22] RO32 Group C - Saturday 21:00 CEST Korean KCM Race Survival 2026 Season 2 [ASL21] Ro16 Group B
Strategy
What's the deal with APM & what's its true value Any training maps people recommend? Fighting Spirit mining rates Muta micro map competition
Other Games
General Games
Nintendo Switch Thread General RTS Discussion Thread Battle Aces/David Kim RTS Megathread Stormgate/Frost Giant Megathread Starcraft Tabletop Miniature Game
Dota 2
The Story of Wings Gaming Official 'what is Dota anymore' discussion
League of Legends
G2 just beat GenG in First stand
Heroes of the Storm
Simple Questions, Simple Answers Heroes of the Storm 2.0
Hearthstone
Deck construction bug Heroes of StarCraft mini-set
TL Mafia
Vanilla Mini Mafia Mafia Game Mode Feedback/Ideas TL Mafia Community Thread Five o'clock TL Mafia
Community
General
Russo-Ukrainian War Thread US Politics Mega-thread Things Aren’t Peaceful in Palestine YouTube Thread Canadian Politics Mega-thread
Fan Clubs
The IdrA Fan Club
Media & Entertainment
Anime Discussion Thread [Req][Books] Good Fantasy/SciFi books [Manga] One Piece Movie Discussion!
Sports
2024 - 2026 Football Thread McBoner: A hockey love story Formula 1 Discussion Cricket [SPORT]
World Cup 2022
Tech Support
[G] How to Block Livestream Ads
TL Community
The Automated Ban List
Blogs
Reappraising The Situation T…
TrAiDoS
lurker extra damage testi…
StaticNine
Broowar part 2
qwaykee
Funny Nicknames
LUCKY_NOOB
Iranian anarchists: organize…
XenOsky
ASL S21 English Commentary…
namkraft
Customize Sidebar...

Website Feedback

Closed Threads



Active: 2209 users

thought experiment

Blogs > nimysa
Post a Reply
nimysa
Profile Blog Joined March 2008
United States383 Posts
September 02 2009 01:12 GMT
#1
Recently I was asked a qeustion that has been boggling my mind for a while now, and alas my thought processes behind answering this question is not too qualified nor too logical toward answering the question; it has been bugging me and driving me crazy, so I thought I should post it here. My knowledge of physics is quite small, but here is the question:
"if a car is travelling at the speed of light, and while travelling, turns it's head lights on, what happens?"

Symmetry
Profile Blog Joined June 2009
Canada294 Posts
September 02 2009 01:18 GMT
#2
Light travels at the same speed from all frames of reference.
micronesia
Profile Blog Joined July 2006
United States24768 Posts
Last Edited: 2009-09-02 01:20:12
September 02 2009 01:19 GMT
#3
It would shoot ahead of you at 3e8 m/s from your perspective.

Your time would dilate in order to make up for the apparent discrepancy an outside observer would see.

edit: I took the question to mean your car was moving at ALMOST the speed of light so it would make sense.
ModeratorThere are animal crackers for people and there are people crackers for animals.
Severedevil
Profile Blog Joined April 2009
United States4839 Posts
Last Edited: 2009-09-02 01:22:06
September 02 2009 01:19 GMT
#4
I'm pretty sure light doesn't care how fast its emitter is moving, and a car can't travel at the speed of light since it's a massive object.

Anyways, I think the light appears to be moving at the speed of light from the perspective of a viewer in the car (as Micronesia said) as well as from a stationary perspective, but time is different from the perspective of the car as from the perspective of a stationary viewer. (Hence the slower aging for people going near the speed of light.)
My strategy is to fork people.
Murlox
Profile Blog Joined March 2008
France1699 Posts
Last Edited: 2009-09-02 01:22:08
September 02 2009 01:20 GMT
#5
SC2 beta key for the driver.

edit : and yeah, car is a massive object.
Resistance ain't futile
Rev0lution
Profile Blog Joined August 2007
United States1805 Posts
Last Edited: 2009-09-02 01:25:48
September 02 2009 01:21 GMT
#6
I really don't understand the question.

What happens is so broad a question that you can really answer it in many ways.

1) The car remains the same at constant speed.
2) In the point of view of a bystander who could see the car moving at the speed of light would not see the light emiting from the car if standing on its side. Since the car and the light are traveling at the same speed the shining of the light would be diminished so low that you could not notice it.
3) Standing in front of the car you would see a ray of light passing you by.


etc.

Another reason the light can't project itself outside of the car is because it would mean that the light of the car is traveling faster than the car itself. Since nothing can travel faster than the speed of light. You'd probably not see light coming from the car if you were looking at it pass you by.

you -> looking at this direction car -^ lights going that way.
My dealer is my best friend, and we don't even chill.
sigma_x
Profile Joined March 2008
Australia285 Posts
September 02 2009 01:30 GMT
#7
Good work! that is the very thought experiment that got Einstein into developing special/general relativity.
vAltyR
Profile Blog Joined July 2008
United States581 Posts
September 02 2009 01:31 GMT
#8
Relativity is awesome. We usually think of time and distance as constant, whereas speed is changing depending on both time and distance. In actuality, it's the other way around. Speed remains constant, and time and distance is what changes to keep it constant.
내 호버크라프트는 장어로 가득 차 있어요
Sky
Profile Blog Joined July 2004
Jordan812 Posts
Last Edited: 2009-09-02 03:35:07
September 02 2009 01:56 GMT
#9
Well nimysa, if you had fun trying to figure that problem out, you should check...

Public Science Papers

Many research papers have other ideas that weren't touched upon included in the "limitations" or "conclusions" section. The drawback being that there are a lot of terms that have complex meanings.

At least you have that quality of dwelling on something unknown to you.

+ Show Spoiler +
Always favored Feynman over Einstein... Feynman was a PLAYA!!!
...jumping into cold water whenever I get the chance.
Pawsom
Profile Blog Joined February 2009
United States928 Posts
September 02 2009 01:59 GMT
#10
On September 02 2009 10:20 Murlox wrote:
SC2 beta key for the driver.


Haha
theonemephisto
Profile Blog Joined May 2008
United States409 Posts
September 02 2009 02:01 GMT
#11
That's why the car CAN'T travel at the speed of light.

From the perspective of the DRIVER, the light would zoom ahead of you at the speed of light.

From the perspective of the BYSTANDER, the light would still be moving at the speed of light, just as fast as the car is. Which is impossible. Which is why it's theoretically impossible to go the speed of light.

Now if the car was moving at ALMOST the speed of light, time would dilate for the car, making the speed of the headlight seem the same from both perspectives.
KwarK
Profile Blog Joined July 2006
United States43902 Posts
September 02 2009 02:01 GMT
#12
On September 02 2009 10:31 vAltyR wrote:
Relativity is awesome. We usually think of time and distance as constant, whereas speed is changing depending on both time and distance. In actuality, it's the other way around. Speed remains constant, and time and distance is what changes to keep it constant.

I very much dislike this. It makes my brain hurt to think about just how far I'm moving when you take the expansion of the universe and the whirling of galaxies into account.
ModeratorThe angels have the phone box
ghostWriter
Profile Blog Joined January 2009
United States3302 Posts
September 02 2009 02:20 GMT
#13
On September 02 2009 11:01 Kwark wrote:
Show nested quote +
On September 02 2009 10:31 vAltyR wrote:
Relativity is awesome. We usually think of time and distance as constant, whereas speed is changing depending on both time and distance. In actuality, it's the other way around. Speed remains constant, and time and distance is what changes to keep it constant.

I very much dislike this. It makes my brain hurt to think about just how far I'm moving when you take the expansion of the universe and the whirling of galaxies into account.


Have you ever seen the pictures where they compare the sizes of the earth to jupiter/the sun then the solar system to the largest stars ever discovered?

This is seriously mindblowing.
Sullifam
citi.zen
Profile Joined April 2009
2509 Posts
September 02 2009 03:14 GMT
#14
Technically the answer is indeterminate, since the relative velocity formula contains a 0/0.

+ Show Spoiler +
v = (w - u)/(1 - wu/c2), where u = c
Aut viam inveniam, aut faciam.
Dasher
Profile Blog Joined February 2009
United States71 Posts
September 02 2009 03:31 GMT
#15
On September 02 2009 10:18 Symmetry wrote:
Light travels at the same speed from all frames of reference.

Not true!
http://en.wikipedia.org/wiki/Slow_light
"My favorite race is zerglings"
micronesia
Profile Blog Joined July 2006
United States24768 Posts
September 02 2009 03:37 GMT
#16
On September 02 2009 12:14 citi.zen wrote:
Technically the answer is indeterminate, since the relative velocity formula contains a 0/0.

+ Show Spoiler +
v = (w - u)/(1 - wu/c2), where u = c

First of all that's no surprise since a massive object can't travel at the speed of light anyway (hence my claim that we should assume the car is moving very close to the speed of light). Second of all I don't believe you can use that formula for photons.
ModeratorThere are animal crackers for people and there are people crackers for animals.
CharlieMurphy
Profile Blog Joined March 2006
United States22895 Posts
Last Edited: 2009-09-02 05:41:25
September 02 2009 05:40 GMT
#17
the most basic answer would be the lights go on but don't seem to shine anywhere.

A better way to think of it is if you take a ray of light and assume that it can shoot off another ray of light. But since they both move the same speed it would just be a brighter ray, not a longer ray.
..and then I would, ya know, check em'. (Aka SpoR)
micronesia
Profile Blog Joined July 2006
United States24768 Posts
September 02 2009 05:57 GMT
#18
On September 02 2009 14:40 CharlieMurphy wrote:
the most basic answer would be the lights go on but don't seem to shine anywhere.

A better way to think of it is if you take a ray of light and assume that it can shoot off another ray of light. But since they both move the same speed it would just be a brighter ray, not a longer ray.

This is the second time tonight I am speechless.
ModeratorThere are animal crackers for people and there are people crackers for animals.
Nitrogen
Profile Blog Joined February 2008
United States5345 Posts
September 02 2009 06:01 GMT
#19
On September 02 2009 14:57 micronesia wrote:
Show nested quote +
On September 02 2009 14:40 CharlieMurphy wrote:
the most basic answer would be the lights go on but don't seem to shine anywhere.

A better way to think of it is if you take a ray of light and assume that it can shoot off another ray of light. But since they both move the same speed it would just be a brighter ray, not a longer ray.

This is the second time tonight I am speechless.


LOL.
UNFUCK YOURSELF
Please log in or register to reply.
Live Events Refresh
Next event in 2h 12m
[ Submit Event ]
Live Streams
Refresh
StarCraft 2
ProTech153
CosmosSc2 27
StarCraft: Brood War
Britney 15551
Calm 2626
ggaemo 224
firebathero 126
Dewaltoss 118
SilentControl 11
Dota 2
capcasts106
League of Legends
Reynor93
Counter-Strike
byalli397
Super Smash Bros
PPMD48
Heroes of the Storm
Liquid`Hasu373
Other Games
summit1g11853
tarik_tv5425
FrodaN715
shahzam403
C9.Mang0236
ArmadaUGS116
ZombieGrub62
QueenE46
Trikslyr37
ViBE9
Organizations
Other Games
BasetradeTV517
Counter-Strike
PGL102
StarCraft 2
angryscii 85
Blizzard YouTube
StarCraft: Brood War
BSLTrovo
sctven
[ Show 22 non-featured ]
StarCraft 2
• davetesta36
• musti20045 30
• RyuSc2 23
• LaughNgamezSOOP
• sooper7s
• AfreecaTV YouTube
• intothetv
• Migwel
• Kozan
• IndyKCrew
StarCraft: Brood War
• HerbMon 32
• Azhi_Dahaki26
• RayReign 16
• STPLYoutube
• ZZZeroYoutube
• BSLYoutube
Dota 2
• masondota21208
• WagamamaTV491
League of Legends
• Doublelift3361
Other Games
• imaqtpie1411
• Scarra792
• Shiphtur144
Upcoming Events
Replay Cast
2h 12m
Escore
12h 12m
WardiTV Map Contest Tou…
13h 12m
OSC
17h 12m
Big Brain Bouts
18h 12m
MaNa vs goblin
Scarlett vs Spirit
Serral vs herO
Korean StarCraft League
1d 5h
CranKy Ducklings
1d 12h
WardiTV Map Contest Tou…
1d 13h
IPSL
1d 18h
WolFix vs nOmaD
dxtr13 vs Razz
BSL
1d 21h
UltrA vs KwarK
Gosudark vs cavapoo
dxtr13 vs HBO
Doodle vs Razz
[ Show More ]
CranKy Ducklings
2 days
Sparkling Tuna Cup
2 days
WardiTV Map Contest Tou…
2 days
Ladder Legends
2 days
BSL
2 days
StRyKeR vs rasowy
Artosis vs Aether
JDConan vs OyAji
Hawk vs izu
IPSL
2 days
JDConan vs TBD
Aegong vs rasowy
Replay Cast
3 days
Wardi Open
3 days
Afreeca Starleague
3 days
Bisu vs Ample
Jaedong vs Flash
Monday Night Weeklies
3 days
RSL Revival
4 days
Afreeca Starleague
4 days
Barracks vs Leta
Royal vs Light
WardiTV Map Contest Tou…
4 days
RSL Revival
5 days
Replay Cast
6 days
The PondCast
6 days
WardiTV Map Contest Tou…
6 days
Liquipedia Results

Completed

Proleague 2026-04-15
RSL Revival: Season 4
NationLESS Cup

Ongoing

BSL Season 22
ASL Season 21
CSL 2026 SPRING (S20)
IPSL Spring 2026
KCM Race Survival 2026 Season 2
StarCraft2 Community Team League 2026 Spring
WardiTV TLMC #16
Nations Cup 2026
IEM Rio 2026
PGL Bucharest 2026
Stake Ranked Episode 1
BLAST Open Spring 2026
ESL Pro League S23 Finals
ESL Pro League S23 Stage 1&2
PGL Cluj-Napoca 2026
IEM Kraków 2026

Upcoming

Escore Tournament S2: W3
Escore Tournament S2: W4
Acropolis #4
BSL 22 Non-Korean Championship
CSLAN 4
Kung Fu Cup 2026 Grand Finals
HSC XXIX
uThermal 2v2 2026 Main Event
2026 GSL S2
RSL Revival: Season 5
2026 GSL S1
XSE Pro League 2026
IEM Cologne Major 2026
Stake Ranked Episode 2
CS Asia Championships 2026
IEM Atlanta 2026
Asian Champions League 2026
PGL Astana 2026
BLAST Rivals Spring 2026
TLPD

1. ByuN
2. TY
3. Dark
4. Solar
5. Stats
6. Nerchio
7. sOs
8. soO
9. INnoVation
10. Elazer
1. Rain
2. Flash
3. EffOrt
4. Last
5. Bisu
6. Soulkey
7. Mini
8. Sharp
Sidebar Settings...

Advertising | Privacy Policy | Terms Of Use | Contact Us

Original banner artwork: Jim Warren
The contents of this webpage are copyright © 2026 TLnet. All Rights Reserved.