Yes and no.
All time travel depends on how restrictive time travel is. There are several types of time travel!
Note that if everybody had a time machine, Hawkins should have had a booming party on 28th of June 2009, to which he sent out the invitations on the 29th of June. He gave it to remind of his 1992 conjecture that travel into the past is effectively ...
Worlds according to Novikov's self-consistency principle would remain consistent. This principle argues that, if time travel is viable, it is simply impossible to travel back in time to cause an inconsistency. The universe will intervene.
A famous challenge was the Polchinski Paradox, which would be a good place to start looking at the challenges of a ...
What if you can only view the past?
With the amazing Chronovisor 9000
We can know who killed that hippie at the cross 2000 years ago.
We can get to witness the Ancient World Wonders!
Fancy looking how beautiful Cleopatra was?
It allows everyone to get a time machine and yet the TIMELINE is safe.
Brb, I have to snap pictures of early horses for my ...
I'll fix this mess. - Universe
A really good source for this type of question I feel is the Orion's Arm Universe. That page goes over several of the more popular and scientifically backed theories around time travel.
I wanted to point out one theory that could be very interesting for your universe. To quote the above link:
Such a lack of continuity ...
Time travel is bad enough when one person has it. Give it to everyone, and you're aiming for a world of confusion.
However, there is a way of getting around this, and the answer lies in what it means when you "create a new timeline". The fact that going back in time always creates a new timeline means that people in already existing timelines can never be ...
I don’t think it’s a realistic possibility.
Having arrived “just before the battle” the king will be busy and in no mood to speak at length to some wandering unknown idiot ranting nonsense. Attempting to impress any of his lieutenants would similarly be counterproductive for similar reasons and even if some sort of demonstration was successful it would more ...
The grandfather paradox works in single timeline only if you decide it works there. Otherwise the attempt on your grandfather life was always there. It was just unsuccessful.
The attempt was successful. And it's called "we need to kill Adolf Hitler in the cradle". Which result in newborn Adi being killed but being replaced by another baby by the ...
Just because you intend to change history, doesn't mean you can.
As a non-time-travel example - just because you decide to win the lottery this week, doesn't mean you will. Just because you decide to get that perfect job, doesn't mean that the company will choose you from all the possible candidates. Anyone who thinks that they can change history is being ...
While your question focused on time travel in relation to different models of time. Time travel in different models of time will have different paradoxes or not (depending on the nature of time in each model).
For example, a multiverse where time travellers either go to timelines where no matter what they do can create a causality violating event or they ...
Ah, time travel. Be warned that it is very difficult to write a time travel story that is both consistent and interesting. But if done right, the result can be amazing!
Trish's answer lists a number of different possibilities. I would like to add one more: Time travel in the Multiple World multiverse.
IndigoFenix's answer also talks about Multiple Worlds,...
Become a miracle healer.
Good medics were simply not found, so someone with a basic knowledge of modern medicine can easily build themselves a reputation with a handful of patients. Once the king hears about you, you will be summoned. From there, anything that comes out of your mouth will be seriously considered.
What will they do?
First, this ship will be confused if they end up in 1942 on accident. As Hyfnae notes in the comments, their primary method of navigation will no longer function. After this, they're likely to try to establish where they are, and will do this at night fall by the stars. From there, they'll use paper charts to try to navigate back to ...
Aside from the variants already provided in other answers, there is another model of time travel effects that can be played with.
In this case, it's the "propagational change" type of time travel. Think of what happens to Marty McFly in Back To The Future Part 1 - some of his actions interfere with his own parents getting together, and it gradually ...
This is something that the comic book Universal War One covers, the author Denis Bajram had a lot of work to keep it coherent with only one timeline.
This is really an interesting read for anyone willing to read a hard SF story with time travel.
More on https://tvtropes.org/pmwiki/pmwiki.php/ComicBook/UniversalWarOne
And answer that often comes is the following:
if you go back in time you make a new timeline.
Ok why not but then what about the "present" timeline? The one you went out from.
I believe the present time line will be emptied because every one will want to travel back in time to create it's own timeline in hope of improving their life condition.
Then the ...
I believe what you describe is possible in simulation theory. Imagine that the time machine created an enormous black hole. Time is inscribed on the event horizon of this black hole, much like a video recording. The original particles are destroyed in this process, so there's no question that this is the only reality in this patch of spacetime.
To achieve this, I need to learn king Harold Godwinson's trust
Why? You want to change the battle outcome or to become BFF's forever?
You just need to kill Wilhelm before battle. Depending on chosen time-traveling theory you either succeed or your attempt was factual and you failed.
To try to assasinate you use XXI century computer games knowledge. You ...